Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention relates to a steering system
for a train of vehicles or cars which do not move on rails.
It is known to provide a conveying system,
particularly for mining applications, wherein a series of
conveyors are mounted on wheels so as to make the system
transportable. Because of the manner in which mines are
developed and extended, it may be necessary for the rather
long conveyor system to be moved along a substantially curved
or zig zag course. This has made it difficult in the past and
time consuming to move the conveyor system when this is
required. It will be appreciated that movement of the
conveyor system is required fairly frequently as the mining
machine advances in the mine.
Attempts have been made in connection with a movable
conveyor system to have each vehicle track in a true manner
behind the vehicle in front of it. One such system is
disclosed in U.S. patent 4,382,607 issued May 10, 1983 to
Edward T. Voight. This known system uses an elongated
steering bar pivotably connected to each of adjacent vehicles
at end portions of the bar permitting angular orientation of
each vehicle in respect to the steering bar and other ;
vehicles. Each end of the steering bar is linked to the near
pair of vehicle wheels through wheel yoke pivot arms about
king pin type pivots. Movement of the steering bar about its
pivotal connection is said to provide proportional turning of
the wheels to affect steering and tracking of one vehicle
following another in either direction.
U.S. patent 3,783,444 issued January 29, 1974 to
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Joseph McWilliams also describes a steering control for a
power driven mobile conveyor. The conveyor frame is provided
with a pair of wheels at each end with one wheel being power
driven and ~he other wheel being of the idler caster type.
The driven wheel is selectively power steerable about a
vertical axis through a range of 180 degrees or more. The
steerable wheels may be positioned transversely,
longitudinally or diagonally of the conveyor frame.
The present invention provides an improved system
for steering a plurality of vehicles in a train, which train
may comprise a mobile conveyor system. The steering system
disclosed herein is for a plurality of vehicles with a number
of pairs of steerable propelling devices or wheels. The system
includes a control mechanism for controlling power means for
steering each pair of propelling devices located behind one
pair of propelling devices. Each axle in the train, except
for the two axles at opposite ends of the train, are pivotally
connected to adjoining vehicles by front and rear pivot
devices.
The steering system disclosed herein operates by
determining the current steering angle of the pairs of
steerable propelling devices or wheels in the system, and by
determining the distance travelled by the propelling devices
in the train in order to calculate the location of trailing
pairs of steerable propelling devices in the train. This
computer operated system is able to set the steering angle of
trailing pairs of steerable wheels so that they will have the
same steering angle as the one pair of wheels had when they
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were at the same location. In this way, each car in the train
will accurately track the path of movement of the leading end
vehicle.
According to one aspect of the invention, a steering
system capable of steering a plurality of vehicles in a train
includes one pair of propelling devices, each separately
connected at a generally vertical pivot to an axle of one of
the vehicles and means for steering this one pair of
propelling devices as the train moves over the ground. There
are at least two further pairs of steerable propelling
devices, each of these further pairs being connected to an
axle of one of vehicles and supporting same. Each propelling
device in each of the further pairs is separately connected at
a generally vertical pivot to its axle. Each axle in the
train, except for the two axles at opposite ends of the train,
are pivotally connected to adjoining vehicles by front and
rear pivot devices each providing a vertical pivot axis. Each
front pivot device is located forwardly of its respective axle
and each rear pivot device is located rearwardly of its
respective axle. There is also apparatus for locking each
pivotable axle in a position at right angles to the
longitu~1n~1 centreline of either adjoining vehicle. Power
means are provided to steer each of the further pairs of
propelling devices and control means control the power means
in order to set the steering angle of each of the further
pairs of propelling devices. The control means includes means
for storing a series of electrical signals each related to the
steering angle of said one pair of propelling devices at a
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certain location as the train is travelling on the ground.
There are also means for determining the amount of time the
propelling devices in the train have been travelling and means
for sending directed turn signals to the power means for the
further pairs of propelling devices in order to operate the
power means. The control means sets the steering angle of
each further pair at substantially the same steering angle
that the one pair of propelling devices had when they were at
the location where the particular further pair is currently
located.
In the preferred embodiment, the control means
includes means for determining the current steering angle of
each of the one and the further pairs of propelling devices or
wheels and generating electrical signals indicative of the
current steering angles of these one and further pairs. The
means for generating the directed turn signals can be a
programmable logic controller.
According to another aspect of the invention, a
cascading mohile conveyor comprises a plurality of vehicles
pivotally connected together in the form of a train with each
vehicle having part of a conveying system arranged thereon.
These vehicles include a loading vehicle located at a rear end
of the train, at least one intermediate vehicle and an
unloading vehicle located at the front end of the train.
There are one pair of propelling devices each separately
connected at a generally vertical pivot to an axle of one of
the vehicles and means for steering this one pair of
propelling devices. Further pairs of steerable propelling
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devices are each pivotally mounted on an axle of a respective
vehicle and they support these vehicles. Each axle in the
train, except for the two axles at opposite ends of the train,
are pivotally connected to adjoining vehicles by front and
rear pivot devices each providing a vertical pivot axis. Each
front pivot device is located forwardly of its respective axle
and each rear pivot device is located rearwardly of its
respective axle. There is also apparatus for locking each
pivotable axle in a position at right angles to the
longitudinal centreline of either adjoining vehicle. A power
mechanism, such as a hydraulic cylinder, steers each of these
further pairs of propelling devices and electrical control
means control the power mechanism in order to set the steering
angle of each of the further pairs of propelling devices. The
control means includes means for determining the distance the
propelling devlces in the train have travelled and means for
sending electrical turn signals to the power mechanism for the
further pairs of propelling devices in order to operate the
power mechanism. The control means sets the steering angle of
each further pair at substantially the same steering angle
that the one pair of propelling devices had when they were at
the same location where the particular further pair is
currently located.
Further features and advantages will become apparent
from the following detailed description taken in conjunction
with the accompanying drawings.
In the drawings, ~-
Figure 1 is a side elevation of the rear end loading ~
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car and a first intermediate car in a conveyor system made of
a number of units or cars constructed in accordance with the
invention;
Figure 2 is a side elevation showing the front end
car which is the unloading car of the conveyor system;
Figure 3 is a plan view of the front end car in the
train and showing how a cross-conveyor mounted thereon can be
swung to one side to transfer material to a stationary
conveyor system;
Figure 4 is a plan view of an intermediate car of
the train;
Figure 5 is a plan view of the rear end loading car
of the train;
Figure 6 is a detail view illustrating the steering
mechanism for one of the cars of the train;
Figure 7 is a side elevation, partly in cross-
section, providing a detail view of the mounting for each
wheel and the motor drive;
Figure 8 is an axial cross-section of a linear
~20 displacement transducer device used to measure the steering
angle;
Figure 9 is a front elevation of the steerable axle
~, ,
assembly of Figures 6 and 7;
Figure 10 is an electrical circuit diagram showing
25the electrical controls for steering the unloading car; ~-
Figure 11 is an electrical circuit diagram showing ~ -
the electrical controls for steering an intermediate car;
Figur~ 12 is an electrical circuit diagram showing
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the electrical controls for steering the loading car; . :
Figure 13 is a flow chart of the start-up logic used --
for the steering system of the invention;
Figure 14 is a flow chart of the operating logic
used for the steering system;
Figure 15 is the initial portion of a program line -~
diagram explaining the operation of the computer program used
in the steering system;
Figure 16 is a continuation of the program line
diagram of Figure 15; ~
Figure 17 is the completion of the program line -
diagram of Figures 15 and 16;
Figure 18 is a side elevation of a preferred form of
rear end loading car of a mobile conveyor;
Figure 19 is a side elevation of a preferred form of
an intermediate car of a mobile conveyor; ;~
Figure 20 is a plan view o~ the rear end loading car : .
of Figure 18; ~ :
Figure 21 is a plan view of the intermediate car ~ ;
shown in Figure 19;
Figure 22 is a detail plan view of the pivotable
axle arrangement used at both ends of the intermediate car of
Figure 19;
Figure 23 is a detail elevational view of the
pivotable axle arrangement shown in Figure 22, which view is
partly in cross-section along the line XXIII - XXIII of Figure
22;
Figure 24 is a longitudinal cross-sectional detail
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of a double headed hydraulic cylinder mechanism employed in
the pivotable axle arrangement of Figure 22;
Figure 25 is a cable and equipment schematic layout
for a train comprising the cars of Figures 18 and 19,
5repetitive portions having been omitted for ease of
illustration;
Figure 26 is a first part of a single line power
diagram illustrating the electrical connections between the
various control enclosures and a main disconnect enclosure;
10Figure 27 is the r~ma;nlng, second part of the
single line power diagram;
Figure 28 is a first part of an electrical circuit
diagram for the circuitry in the main control enclosure of the ~:
mobile conveyor of Figures 19 to 21;
15Figure 29 is the rPm~in-ng, second part of the
: electrical circuit schematic for the main control enclosure;
Figure 30 is a schematic diagram of the electrical
: circuit and components in a control enclosure for an
; : intermediate car; and ; :
~ 20Figure 31 is a schematic diagram of the electrical
: circuit and components in a main disconnect enclosure for the
mobile conveyor.
, l l
The major components of a mobile conveyor system
constructed in accordance with the invention are illustrated
25in Figures 1 to 5 of the drawings. This conveyor system 10 is
made up of distinct units or cars (also called vehicles ,
herein) which are mechanically linked together by pivot pins, ~'
there being a single pin 12 for connecting each car to the
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next car in the train. Each car is fitted with its own
continuous conveyor belt 14 which extends in the lengthwise
direction of the car. As known in the industry, instead of
the illustrated conveyor belts, conveyor chains can also be
used on the cars of a mobile conveyor system. The preferred
mobile conveyor system has three different types of cars or
vehicles pivotally connected together in the form of a train.
These cars include a rear end car 16 which is a loading car
with a large chute 18 to catch the material being thrown from
a mining machlne (not shown). The second type of car is an
intermediate car 20 and although only one complete
intermediate car is shown in the drawings, it will be
understood that the intermediate cars make up most of the
train. There can be as many as 20 or more intermediate cars
in the conveyor system. The third type of car or vehicle in
the system is the front end car located at the front or head
of the train. This is an unloading car 22 which generally
carries a cross-conveyor 24. The cross-conveyor which has its
own continuous conveyor belt 26 is used to transfer the mined
material from the mobile conveyor system 10 to a stationary
conveyor system (not shown). A splash guard for the
stationary conveyor is indicated at 28 in Figure 3.
Turning now to a more detailed description of each
of these three cars, the rear end car 16 has a longitudinally
extending frame 30 to the front end of which is connected a
downwardly extending leg 32. Extending forwardly from the leg
32 is a connecting tongue 34 having a hole in its front end to
receive the aforementioned connecting pin 12. The tongue 34
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connects the front end of the loading car to the rear end of
the adjacent intermediate car 20 in such a manner that the
front end of the conveyor on the loading car is positioned
above the rear end of the conveyor belt on the intermediate
car. In each case the articulation point provided by the
pivot pin 12 is preferably directly underneath the loading
point for the car 20 in order to provide a clean transfer of
the mined material whatever the angle between the longitudinal
centre axes of the two cars joined by the pin. ~-
The loading car 16 is also e~uipped with a conveyor
drive gear motor 36. The loading car 16 has only one axle in
the illustrated embodiment and a first pair of wheels 38 is
mounted at opposite ends of this axle. The mounting of these
wheels will be explained in more detail hereinafter in
connection with Figures 6, 7, and 9 of the drawings. However,
it will be appreciated that each of the wheels 38 is
separately connected by a generally vertical pivot to the axle
and can be steered manually with the assistance of a hydraulic
cylinder as explained hereinafter. The push button control
panel for manually steering the loading car 16 is indicated at
37 in Figure 1. This panel has four buttons, two for steering
left or right and two for controlling the motor drive, forward
and reverse. The wheels 38 as well as the other pairs of
whèels described hereinafter could be replaced by short
pivoting tracks if desired, as is known in the mobile conveyor
industry. The term "propelling devices" as used herein is
intended to include both wheels and track devices in the form ~
of endless bands or tracks on which the vehicle is propelled. '-
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- 12
Turning to the construction of each of the
intermediate cars 20, these cars also have a longitudinally
extending frame 40. Extending downwardly from the front end
of each frame 40 is a frame extension 42. A connecting tongue
44 extends forwardly from each extension 42. Each
intermediate car 20 is connected to either another
intermediate car 20 located forwardly thereof or to the
unloading car 22 by means of a connecting pin 12 extending
through the front end of the tongue 44. Because of the
extension 42, the rear end of the conveyor of each
intermediate car is elevated above the front end of the
conveyor of the next intermediate car. Suitable skirting 46
can be provided adjacent the front end of the intermediate car
to catch the material falling onto the conveyor belt at the
transfer point. Also, to provide the necessary flexibility in
the conveyor system, each intermediate car can be provided
with a horizontal pivot 48 located over the two wheels of that
car. This permits the major forward portion of the frame 40
to pivot upwardly or downwardly relative to a short rear
portion 50 of the frame. Like the loading car, each
intermediate car has only one axle to which two wheels 52 are
pivotally connected. Each pair of wheels 52 are steerable by
the stearing system of the present invention. The belt of
each intermediate conveyor also has its own conveyor drive
gear motor 54 which, in the illustrated embodiment, is located
adjacent the front end of the conveyor. Each of the cars of
the train, including the intermediate cars, can also be
provided with a pivot pin located on the longitudinal centre
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line of the car in order to provide a torsional degree of
freedom. The location of the centre line pivot pin for the
intermediate car 20 is indicated at 56 in Figures 1 and 4.
The pivot pin 56 connects together two parallel, adjacent
transverse frame members indicated at 58 which join together
two longitudinally extending frame members that are part of
the complete frame 40. In this way it will be appreciated
that the front portion of the frame 40 can pivot somewhat
about the longitudinal centre axis of the car relative to the
rear portion of the same frame 40.
The unloading car 22 has two axles with a pair of
steerable wheels mounted on each of these axles. Again both
pairs of wheels can be replaced by short tracks if desired.
The front pair of wheels 60 are steerable manually by the
operator of the train. The rear pair of wheels 74 is steered
automatically by the controller described hereinafter. Each
wheel 60 is separately connected at a generally vertical pivot
62 to the car 22.
The unloading car 22 has a lengthwise extending
central frame 64 on which the cross-conveyor is mounted so as
to be pivotable about a vertical axis. The car 22 also has a
vertically extending frame leg 66 extending upwardly from the
central frame 64 and rigidly connected to a longitudinally
extending rearward frame 68. Movably mounted on the rearward
frame is a relatively short belt conveyor 70 which unloads
onto the adjacent cross-conveyor 24. Near the centre of the
rearward frame 68 is a horizontal pivot 72 which is disposed
directly above the axle for the rear wheels 74. The usual
.
... , .:: . . . . ~ i . ~
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- 14 -
skirting 76 is provided on opposite sides of the conveyor 70
in order to catch the material falling from the adjacent
intermediate car 20.
The front axle 78 of the unloading car is rigidly
connected to a front frame section 80 which is located a short
distance above the central frame 64. Two longitudinally
extending members of the front frame 80 are connected to
transverse frame 82. In the illustrated preferred embodiment,
each pair of wheels including the wheels 60 and 74 on the
unloading car are powered by an electric tram motor 84. In one
preferred embodiment, this motor is a five horsepower electric
motor that operates at 1800 RPM and has a 184TC frame. Each
motor 84 is connected to a gear reducer 86 in the form of a
planetary gear box mounted to the differential housing 88 of
the axle ~see Figure 6). A preferred gear reducer for this
: purpose is that sold by Brevini ED2010/MN2-FL635/12. A
: suitable axle for present purposes is a John Deere llS0 Series
steerable axle sold under P/N2561R144311111632.
Turning now to a detailed discussion of the steering
: ~ 20 mechanism for each pair of wheels, reference will be made to
Pigures 6, 7, and 9 which illustrate the rear axle 79 of the
unloading car. It will be appreciated that each pair of
'
steerable wheels in the train is constructed in substantially
the same ~ashion as that illustrated in Figures 6, 7, and 9.
The aforementioned John Deere axle comes equipped with two
hydraulic steering cylinders 90, one at each end of the axle.
It will be understood that each hydraulic cylinder provides
power means for steering its respective wheel by means of a
.. ", . ,.. , . . - - ~
~78~
- 15
steering arm 92 connected to the wheel at one end. The
hydraulic cylinder has a movable rod 94 which is pivotally
connected to the arm 92. To ensure that the wheels of each
pair pivot together they are connected together by a tie rod
96 which is pivotally connected to a further arm 98 at each
end. It will be understood that the arm 98 is connected to ;
lts respective wheel so as to pivot therewith about the
vertical pivot axis. ~'
With specific reference to Figures 7 and 9, the axle
79 is rigidly connected to two horizontal plates 160 by means
of bolts 162. The plates 160 are connected to vertical legs
164 which are connected at the top to the aforementioned
rearward frame 68. Connected to the front of the axle is a
drive line housing 166 and bolted to the front end of this
housing is the aforementioned gear reducer 86. The housing
166 is bolted to the axle by means of an axle input guill 168.
The drive line extends through a drive line locating ring 170
which is arranged at the front end of housing 166. The output
shaft of the gear reducer 86 is connected to the drive line by
means of a drive line yoke adaptor 172.
There are means for determining the current steering ;~
angle of each pair of wheels. In one preferred embodiment
this steering angle is measured using a linear displacement
transducer indicated at 100 in Figures 5, 6, 8 and 9. This
~ .:
transducer is connected to the axle by means of a connecting
plate 102. A preferred form of transducer is that
manufactured by MTS Systems Corporation (Sensors Division) and
sold under the trade mark TEMPOSONICS II ~P/N TTS-RCU0120).
~'-
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- 16 - -
This transducer has a rigid, elongate stainless steel rod 150
which extends into a steel tube 156 which in turn is enclosed
in a mild steel cylinder or housing 104. The steel tube 156
is connected to a rearwardly extending pivot arm 106 by a
5connecting pin 107. The arm 106 is connected to the end of a
pin 108 which pivots with the pivotal movement of the adjacent
wheel. Mounted at the open end of the housing 104 is a brass
gland member 152 having a rod wiper 154 mounted therein. The
steel tube 156 is free to slide axially in the gland member.
10Connected to the inner end of the tube 156 is an annular
magnet 158, such as MTS magnet 201542. It is the linear
movement of the magnet 158 relative to the rod 150 which
enables the LDT to provide the required electrical signal that
indicates the current steering angle of the wheel.
15There are control means for controlling the
hydraulic steering cylinders for each pair of wheels trailing
the wheels of either the loading car or the unloading car in
order to set the steering angles for these further pairs of
wheels. The control means includes means mounted on the first
20axle (the one for the wheels 38 or the wheels 60) to determine
the current steering angle of the first pair of wheels. In
particular, the linear displacement transducer ~hereinafter
referred to as LDT) of the first pair of wheels generates a
first electrical signal indicative of the steering angle of
25the first pair of wheels at a particular point in time. This
electrical signal is sent to a programmable logic controller
(hereinafter referred to as the PLC) which is able to store a
series of these first electrical signals as a train travels on
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the ground. The control system also includes means for 1'
determining the amount of time the wheels in the train have
been travelling from a set point in time. This travelling
time is read by the PLC. After a selected time interval, the
PLC samples and stores the steering angle of the loading car
wheels 38 or the unloading car wheels 60 (depending on the .
,. .~- ~
direction of travel). The PLC provides means for sending
electrical turn signals to the steering cylinders for each of
these further pairs of wheels in order to operate the
hydraulic steering cylinders. The control system thereby sets
the steering angle of each pair of wheels at substantially the
same steering anyle that the first pair of wheels had when
they were at the location where the particular further pair is
currently located. A suitable PLC for this control system is
the Logic Master 9070 sold by General Electric which has
several components including a CPU 731 with an internal
retentive timer.
One form of logic for the PLC is illustrated by the
flow charts of Figures 13 and 14. Figure 13 illustrates how
the system is initialized. The designation CP stands for
steering cylinder position. At startup, the train is arranged
in a straight line and the memory for the steering cylinder
i
position is set at zero. Also all of the steering cylinder
positions in the train are set to zero.
In the flow chart of Figure 14 the term Ti stands -
for constant time increment which is related to the distance
moved. The term To represents the start time for the tramming
operation while the term T stands for the current time. After
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- 18
each steering cylinder position has been set to that indicated
in the memory (as explained above) the PLC reads the steering
angle for the end car that is to be steered manually and
stores this position in the top of its memory. The tram
motors 84 are then operated to commence movement of the train
and this start up time is recorded in the memory of the PLC.
Then periodically the current time T is read from the clock by
the PLC. The PLC will continue to read the clock time until
the lapsed time is equal to or greater than the constant time
increment at which time the start time will be reset to the
current time. When this occurs all of the steering cylinder
positions in the memory of the PLC are moved down one position
in the memory. Next the steering cylinder position or
manually steered car (called the lead car in Figure 13) is
read and stored at the top of the memory. The PLC then sets
each steering cylinder position to the stored steering
cylinder position for the position where the particular set of
wheels is then located. The PLC then determines whether or
not the train of cars is stlll moving or tramming. If the
train has stopped, the tram motors will be stopped and the
process will end. It the train is still moving, this cycle
will repeat itself beginning with the PLC reading the current
clock time.
Another system which can be used for the measurement
of the distance travelled is one employing a radar sensor, for
example that sold by Magnovox (trade mark), Model RGSS101.
The radar sensor can measure the speed of travel of the train
and, using this information along with the travel time, the
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PLC can calculate the distance or location o~ each axle on the
train. When an axle hits a point where the PLC has sampled
and remembers the lead car steering angle, the PLC sets that
axle to the same angle. The PLC sets the steering angle of
each axle by operating an electro-hydraulic valve for the
hydraulic steering cylinders mounted on that axle and by using
the LDT as a feedback.
Figures 10 to 12 of the drawings illustrate the
electrical control system for the unloading car, the
intermediate car, and the loading car respectively. There are
shown in Figure 10 five contactors 1~0, two of which are for
the front pair wheels 60 on the unloading car and two of which
are for the rear pair wheels 74. These contactors are
electrically connected to a 600 volt power supply in a
preferred embodiment. This power supply is also connected to
transformer 182 which converts the 600 volt supply to 120
volts. The line providing 120 volt power is connected to the
PLC indicated at 184. In a preferred embodiment the PLC
includes a genius bus controller, a nine slot-rack, a central
processing unit and a power supply, all of which are available
from General Electric. The central processing unit can be
type 731 from General Electric. The 120 volt power is also
connected by line 186 to an input/output block 188. The block
188 is connected by line 190 to pendant control 192. The
pendant control comprises a joystick mechanism 194, an
emergency stop button 196, a three-position selector switch
198, a start button 200 and a stop button 202. A second
input/output block 204 is connected between the pendant
~' 2~ ~78~3
- 20
control 192 and an analog block 206 by three electrical lines
indicated at 208. Also connected to analog block 206 is a 120
VAC/~10 VDC power supply 210. Connected between the PLC 184
and the contactors 180 is a further input/output block 212.
Also connected between the block 212 and the contactors are
three overloads 214. There are connected to each of these
overloads an electric motor identified by the letter M. The
motor M 60 drives the wheels 60, the motor M 74, and the motor
M HYD drives the hydraulic motor for the unloading car.
There are also shown in ~igure 10 two steering
solenoids indicated at 216, each of which is electrically
connected to input/output block 204. These solenoids are
capable of steering the pairs of wheels 60 and 74 either right
or left as indicated. Connected to the analog block 206 are
lS two Temposonic LDTs 218, one for reading the current steering
angle of the wheels 60 and the other for reading the current
steering angle of the wheels 74.
The control ~iechanism for an intermediate car in the
train is shown in Figure 11. In the system, there are two
electrical contactors 220, each of which is connected to a
supply of 600 volt power. This power is also connected to a
transformer 222 capable of converting the 600 volt power to
120 volts. The 120 volt supply is connected to an overload
22~ at one end and to a further power supply 226 at the other
end. The supply 226 is capable of providing ~10 volts direct
current to an analog block 228. The block 228 which is
available from General Electric, is connected to a Temposonic
LDT 230 which i5 provided to indicate the current steering
.. ~ . , . .... ,, . . . : : ., . , :
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- 21 -
angle of the wheels 52 of the intermediate car. There is also
a steering solenoid 232 which is connected by line 234 to an
input/output block 236. This block is connected to both the
120 volt power supply and to the contactors 220. The overload
224 is connected to the electric motor M 52 (also identified
by reference 84 in Figure 1) used to drive the wheels 52 of
the intermediate car.
Figure 12 illustrates the electrical control
circuitry for the loading car of the train. Again there are
two contactors 240 which are connected to a 600 volt power
supply. The 600 volt supply is connected to a transformer 242
which is capable of converting the 600 volt supply to 120
volts. One side of the 120 volt supply is connected to an
overload unit 244 which is available from Siemen's. The other
side of the 120 volt supply is connected to a further power
supply 246 which is capable of providing ~10 volts direct
current. The power supply 246 is connected to analog block
248. This block is connected at one side to a Temposonic LDT
250 which is provided to measure the current steering angle of
the wheels 38 of the loading car. The analog block is also
connected by means of lines 252 to an input/output block 254
which in turn is connected to pendant control 256. This
pendant control includes a joystick 258, an emergency stop
button 260, a start button 262 and a stop button 264.
Suitable stop, start and stop buttons are available from
Siemen's. The electrical lines 252 are also connected to a
~urther input/output block 266 which is connected to the two
contactors 240. The overload 244 is connected to an electric
-' 2~7~3
- 22
motor M 38 which drives the wheels 38 of the loading car.
The operation of the electrical control system will
now be explained in conjunction with the program line diagrams
of Figures 15 to 17. The aforementioned thermal overloads
214, 220 and 240 are provided to stop the tramming motors if
any one of the motors are loaded beyond their amperage rating.
The contact on the overload will open in an overload
situation, thus stopping power from going to the tram overload
input of the genius bus controller of the PLC. This in turn
stops power from going to the tram overload internal coil in
the PLC, stopping any tramming function of the m~hi ne.
It will be understood that the hydraulic pump of the
machine must be running before the machine will tram or steer.
This pump may be started or stopped from either the loading
end or the unloading end. As indicated, there are start and
stop buttons 200, 202, 262 and 264 at both ends of the train.
One of the hydraulic start buttons is pushed and completes an
input to the PLC which in turn completes an output to the
hydraullc pump magnetic starter and the pump starts. Also
both the loading and unloading cars have emergency stop
buttons 196 and 260. If either of these buttons is pushed,
the button completes an input in the genius bus controller
thereby sending a signal to the PLC which turns on internal
coils stopping all functions of the m~chine.
The unloading car also has the selector switch 198
which is used by the operator to select which end of the train
has control of steering. When the switch is in the "unloading
end steering" position, it completes an input to the genius
: 2~ ~7~3 :
- 23 -
bus controller which sends a signal to the PLC to energize an
internal coil therein. In this way, only the joystick at the
unloading end controls the machine.
The loading car ioystick 258 has control of the
machine if the selector switch 198 is moved to the "loading
end steer "position. Again, a signal will be sent to the
genius bus controller completing an input to the PLC.
The following is an explanation of how the machine
is steered when the selector switch 198 is moved to the
"unloading end steer" position. If the joystick 194 is moved
to the forward position, it completes an input to the genius
bus controller (hereinafter referred to as the "genius block")
which sends a signal to the PLC 184 to energize an internal
coil. This operation is illustrated at the top of Figure 16.
This movement of the joystick completes all the "unloading end
forward" inputs thereby starting the tram magnetic starters
for all of the axles including illustrated axles 60, 74, 52,
and 38. The m~ch-fne moves forward toward the unloading end
direction.
The joystick is moved to the left in order to steer
the unloading car to the left. The movement completes the
unloading left input to the genius block which sends a signal
f - .
to the PLC which in turn turns on the steer left 60 internal
coil. The internal coil outputs a signal to the axle 60
solenoid 216 which moves the wheels 50 to the left. When the
joystick is returned to the centre position, the wheels 60
stop turning left. Then the LDT 218 for the wheels 60 reads
. . .
how far the wheels have turned and sends this information by
21~7~3
- 24
means of an electrical signal to the input of analog block
206. This block transmits the signal to the PLC 184 where it
is stored for the purpose of steering the subsequent axles as
explained hereinafter. The first steering location may be
called location No. 1.
After the machine has trammed forward for T seconds,
a retentive internal timer in the PLC sends a signal to coil
steer 74 which is energized, thereby sending a signal to the
solenoid 216 which steers the wheels 74. This signal is sent
through input~output block 204. The solenoid is energized
until it reaches the same position that solenoid 216 for the
wheels 60 was in at location No. 1. At this position, the
solenoid ~74 will quit turning the wheels left because the LDT
218 for the wheels 74 senses the same angle that the wheels 60
had at this location.
When the machine has trammed ahead for another T
seconds, the retentive internal timer energizes internal coil
steer 52 which energizes the solenoid Z32, thereby moving the
wheels 52 to the same angle that the first wheels 60 had at
location No. 1. Again, when the wheels 52 are turned to the
re~uired angle, the LDT 230 senses this angle and sends an
input through analog block 228 to the PLC, resulting in coil
steer 52 being de-energized.
Assuming for the moment that there is only one
intermediate car and the wheels 38 are the next wheels in a
series of wheels, then after the m~ch;ne has trammed forward
another T seconds, the retentive internal timer will energize
coil steer 38 which energizes the solenoid 270. The wheels 38
2~7~3 :
- 25
are then moved to the same angle that the wheels 60 had at
location No. 1. When the wheels 38 have reached the proper
steering angle, the LDT 250 which measures this angle sends an
input signal to analog block 248 which sends a signal to the
PLC which in turn de-energizes coil steer 38. This sequence
of steps is indicated at 272 in Figure 16.
In the alternative, if one wishes to move in
reverse, the joystick 194 is moved to the reverse position,
thus causing "unloading reverse" input to be energized at the
genius block. This sends a signal to the PLC energizing the
"unload tram reverse" coil. As a result, the reverse tram
coils for wheels 60, 74, 52, and 38 are energized and the tram
reverse magnetic starters operate to cause the machine to tram
in a reverse direction from the unloading end.
When the joystick 194 moves to the reverse position
at the unloading end, the LDT 250 records the position of the
wheels 38 and sends this information as an input to the analog
block 248 which sends it to the P1C to be stored for the new
location No. 1. When the machine has trammed in a reverse
direction for T seconds, the retentive internal timer sends a
signal to internal coil steer 52 which is energized sending a
signal to solenoid 232 through the input/output block
connected thereto. The solenoid 232 is energized until its
wheels reach the same position that the wheels 38 were in at
new location No. 1. The solenoid 232 is de-energized when the
LDT 230 senses the same angle that the LDT 250 had at new
location No. 1.
21~g~3
- 26
When the machine trams reverse for another T
seconds, the retentive internal timer is energized sending a
signal to internal coil steer 74. This internal coil steer is
energized allowing solenoid 216 to be powered through the
input/output block 204. The solenoid 216 is energized until
its wheels reach the same position that the wheels 38 had at
new location No. 1. The solenoid 216 is de-energized when the
LDT 218 senses the same angle that the LDT 250 had at new
location No. 1.
Again, assuming that there is only one intermediate
car, when the machine trams reverse for another T seconds from
the unloading end, the retentive internal timer w:Lll be
energized and will send a signal to internal coil steer 60.
The internal coil steer is energized allowing the steering
solenoid 216 for the wheels 60 to be powered through the
input/output block 204. This solenoid 216 is energized until
its wheels 60 reach the same steering angle that the wheels 38
had at new location No. 1. The solenoid 216 is de-energized
when the associated LDT 21~ senses the same angle that the LDT
250 sensed at new location No.1. This sequence of steering
operations for reverse direction movement is indicated at 274
in Figure 16.
Figures 17 illustrates the same sequence of events
as Figure 16 except that the train is being steered by the
joystick located on the loading tram.
In one embodiment of the steering system there is a
manual override for moving and steering each car on the train.
If a steering or tracking error should occur, each car can be
~ 1~7~3 ~ -
. . .:
- 27 -
steered and moved independently of all other cars for re-
alignment. Upon movement of the whole machine, the normal -~
steering sequence is utilized with the manually re-aligned car
in an adjusted path. When the manual override is used, each
car is steered and moved with manual controls (of known
construction) located on that car. For example, a push button
control panel 161 can be provided on each intermediate car and
a further push button control panel 163 can be provided on the
front car for purposes of this manual override feature. Each
panel 161 has four push buttons 280 to 283, two o~ which are
for steering the wheels either left or right. The other two
buttons are for forward and reverse drive. The location of
these four buttons in the control circuit is shown in Figure
11. The control panel 163 for the front car has six push
buttons 285 to 290 illustrated in Figure 10. The buttons 285 ;
and 286 are for steering the wheels 60 either left or right --
while buttons 287 and 288 are for steering the wheels 74
either left or right. The control buttons 289 and 290 are for i
forward or reverse drive.
A preferred embodiment of the conveyor system of
this invention will now be described with particular reference
to Figures 18 to 24 of the drawings. Except as specifically
described hereinafter, this preferred system is constructed in
a similar manner to the embodiment illustrated in Figures 1 to
5 and operates in a similar fashion. In this preferred
system, there are also three different types of cars or
vehicles pivotally connected together in the train. These cars
include a rear end car 300 which i9 a loading car and an
21~8~
- 28
intermediate car 302, a complete view of which is shown in
Figures 19 and 21. As with the first embodiment, these
intermediate cars 302 make up most of the train. The third
type of car or vehicle in the system is the front end car 304
which is similar in construction to the unloading car 22 of
the first embodiment except for the differences noted
hereinafter in connection with the cars or vehicles 300 and
302.
The rear end car 300 has a horizontally extending,
centrally located main frame 306 near the front end of which
is connected a horizontally extending, transverse frame 307
which is connected by bolts to the top of the main frame.
Extending upwardly from opposite ends of frame 307 are two
frame sections 308. Extending forwardly from each section 308
at a slight incline is a forward conveyor support frame 310.
At the front end of the frames 310 there is mounted a conveyor
roll 312. A pivot device 311 described in further detail
hereinafter is located at the front end of a main frame 306
and is just to the rear of the axle for the pair of wheels 314
2Q of the adjoining intermediate car. -~
Located near the rear end of the main frame 306 is
a horizontal, transverse frame member 315 which is bolted to
the main frame. ~xtending upwardly from opposite ends of the
frame member 315 are two frame sections 316 which are shorter
than the frame sections 308 in order to provide the desired
incline to conveyor 318. Extending rearwardly from each frame
section 316 is a rear conveyor support frame 320. Near the
rear end of the frames 320 is rotatably mounted rear conveyor .-
~.: .: . . . . .. .
21~7~3
- 29 -
roller 322. The rear ends of the frames 320 are supported by
short vertical frames 324, the bottom ends of which are
connected to the main frame 306 by two horizontally extending
rear end frame members 326 to which rear axle 328 is bolted.
It will be understood that in the rear end car 300 the axle
328 is not free to pivot about a vertical pivot axis relative
to the main frame of the vehicle unlikely the axles of the
intermediate cars 302 described hereinafter. The frame 306 is
split near its rear end to accommodate electric tram motor
331. Extending below the motor is a lower, horizontal frame
extension 332 while above the motor is an upper horizontal
frame extension 334.
Turning to the construction of each of the
intermediate cars 302, these cars also have a central,
horizontal main frame 336. The conveyor 338 is supported on
the intermediate car in a similar manner to the supporting
arrangement for the conveyor 318. However in the intermediate
car, the two rear conveyor support frames 340 extend
rearwardly and slightly upwardly as shown in Figure 19 and
they are not supported at the rear end.
Figures 22 and 23 illustrate in detail the axle
support arrangement for each intermediate car 302 and for the
I ~, I .
rear end of the front end car 304. Reference will be made to
the axle support for the wheels 314 but it will be understoQd
that the wheels of the other intermediate cars and the wheels
at the rear end of the front end car are mounted in a similar
fashion. The pair of wheels 314 are mounted on their own axle
342. It will be understood that the axle ~ se is the same
'" 21~7~
- 30
type of axle as used in the first embodiment of Figures 1 to
5. However the axle 342 is pivotally connected to the
adjoining vehicles, in this case rear end car 300 and
intermediate car 302, by a front pivot device 344 and a rear
pivot device 311, each of these devices providing a vertical
pivot axis. The front pivot device 344 is located close to
and forwardly of its respective axle and rear pivot device 311
is located close to and rearwardly of the axle 342. As
illustrated the front pivot device 344 comprises lower and
upper pivot pins 345, 346 which are mounted respectively in
lower and upper frame extensions 332 and 334. These pivot
pins extend through holes formed in a subframe 348. The axle
342 is rigidly mounted to this subframe which has a s~uare
hole at 350 through which the axle drive 352 extends. The
rear end o~ this subframe 348 is provided by horizontally
extending frame 354. On the rear surface of the frame 354 is
mounted a pintle hitch 356 which forms part of the rear pivot
device 311. The other half of this pivot device is formed by
a tow ring 358. A suitable form of pintle hitch is that sold
by Holland Hitch Co. under model no. PH-T-60-AOL-8. A
suitable form of tow ring is that sold under the trade name
Princess Auto model no. 3807195. It will be understood that
the pintle hitch in a known manner enables the two adjoining
vehicles or cars to be detached readily from one another, if
desired.
Preferably, the pivot pins 345 and 346 are mounted
in ball bushings indicated at 360 to permit the subframe to
:
7 ~ ~ 3
pivot freely. A suitable ball bushing is that sold~by
Torrington, model no. 20SF32.
In the preferred steering system illustrated in
Figures 22 and 23, there are means for locking the axle 342 in
a position at right angles to the longitudinal centre line of
either the vehicle immediately in front of the axle or the
vehicle immediately to the rear thereof. The preferred
locking mechanism for each axle comprises first and second
hydraulic cylinder mechanisms 362 and 364. The first
mechanism 364 is capable of preventing pivotal movement about
the front pivot device 344 while the second mechanism is
capable of preventing pivotal movement about the rear pivot
device 311. Each hydraulic cylinder mechanism 362 and 364 is
preferably double headed and is constructed in the manner
illustrated in detail in Figure 24. The front end of the
mechanism 364 is pivotally connected to horizontal frame 315
by means of a lug 366. The rear end of a mechanism 364 is
pivotally connected to the axle and axle subframe 348 by means
of connecting lug 368. The front end of the mechanism 362 is
pivotally connected to the axle 342 by means of a rigid
connecting arm 370 which extends rearwardly from the axle
subframe. The rear end of the mechanism 362 is pivotally
.~ .
connected to the main frame 306 by means of lug 372.
The construction of the hydraulic cylinder mechanism
362 is detailed in Figure 24 and it will be understood the
mechanism 364 is constructed in a similar fashion. The
mechanism includes a left cylinder portion 376 and a similar
right cylinder portion 378 and th~se cylinder portions are
2~7~3
- 32
connected together by means of a common rod 380 which has an
oil channel 382 extending along its central axis for most of
its length. This oil channel provides hydraulic oil to the
left cylinder portion 376 by means of a short end passage 384.
The hydraulic oil enters the right cylinder portion 378
through an oil port 386 which of course connects to a suitable
hydraulic hose (not shown). The outer ends of both cylinder
portions are closed by circular end plates 388. On these
plates are mounted a connecting extension 390 having an
opening for a pivot pin. On each end of the rod is mo~mted a
piston 392, 394 adapted to slide in its respective cylinder
portion. The inner end of each cylinder portion is fitted
with an annular closure 396 having a central opening through
which the rod is free to slide. Suitable hydraulic oil seals
are provided in each member 396 and about each piston in a
known manner. The hydraulic cylinder mechanism 362 is shown
in Figure 24 in the pressured or locked position. It will be
understood that each hydraulic cylinder mechanism moves to
this mid-stroke position upon being pressurized. In this
2~ position, the axle is locked in a position where it is
perpendicular to the centerline of the vehicle to whose frame
the hydraulic cylinder mechanism is connected. When the oil
I, I ! . :
port 386 is vented to the hydraulic oil reservoir (not shown), -~
the hydraulic cylinder mechanism is free to extend or retract
as the mobile conveyor moves along the ground. The left
cylinder portion 376 locks in position after extension of the
rod into this portion while the right cylinder portion locks
in position after retraction of the rod from the portion 378.
~'.
'~' 2:l~7~3
It will be understood that the above-mentioned PLC
184 also controls the hydraulic cylinder mechanisms 362, 364
for the pivoting axles of the mobile conveyor. -
It should be understood that the wheel pairs in the
preferred conveyor system illustrated in Figures 18 to 23 are
steered in the same manner as in the first described
embodiment and the mechanism for pivoting each wheel about its
vertical axis is the same. In the illustrated preferred
embodiment of Figures 18 to 23, the wheel pairs are located as
close as possible to the material tra~ectory landing point.
Thus, as shown in the drawings, the axle for each pair of
wheels is almost directly below the unloading end of the
conveyor located immediately to the rear of that axle.
In the mobile conveyor of Figures 18 to 23, when the
mobile conveyor is moving rearwardly, that is in the direction
of rear end car 300, the hydraulic cylinder mechanism 362 of
the second axle 342 is pressurized causing it to go to its
mid-stroke. Thus the second axle 342 i.e. the axle for the
first intermediate car or vehicle) is positioned at right
angles in plan view to the longitudinal centre line of the ~-
; rear end car 300. At the same time the cylinder mechanism 364
located in front of the second axle 342 is free to float
1~ ' , .
allowing the axle to pivot about the vertical pivot axis
provided by front pivot device 344. The PLC operates the
other pivoting axles of the mobile conveyor in a similar
fashion when the conveyor is tramming in this rearward
direction. However, when the tramming direction is in the
forward direction, that is in the direction of the front end
~ 2~7~3 ~'
- 34
car 304, then the hydraulic cylinder mechanism 364 of the
second axle 342 is adjusted to mid-stroke forcing this axle to
be at right angles to the longitudinal centerline of the
intermediate car 302. In this situation, the pintle hitch or
rear pivot device 311 will now provide a vertical pivot axis
since the hydraulic cylinder mechanism 362 is allowed to float
by the PLC. Thus the towing opera~ion for this preferred
mobile conveyor can be compared to the situation of towing a
boat trailer behind a car. It is well known that it is easier
to tow a boat trailer behind a car than it is to back up a
trailer using the car (for example when launching a boat).
For this reason, the embodiment illustrated in Figures 18 to
23 is preferred over that illustrated in Figures 1 to 6 of the
drawings.
Figure 25 illustrates the cable and equipment layout
for the preferred mobile conveyor o~ Figures 18 to 21.
Illustrated schematically are the wheels on one side of the
rear end car 300, the intermediate car 302 that is immiediately
to the rear of the front end car, and the front end car 304.
Thus, the rear axle of the rear car is indicated at 328.
Illustrated schematically in this drawing are the control
enclosures containing most of the electrical controls for the
mobile conveyor including a main control enclosure 400 mounted
on the rear car, an intermediate vehicle control enclosure 402
mounted on each intermediate car and also on the front end car
and a main disconnect enclosure 404. Also mounted on the rear
car i~ operator control pendant 256 and a similar operator
control pendant 192 is mounted on the front car. Other
'j: . .
~'' 2~7~
features illustrated schematically in ~igure 25 are the five
horsepower motors 331 that power each pair of wheels, the
hydraulic steering valves 406 used to steer each pair of
wheels, an axle position sensor 408 and a single optical
incremental encoder 410, the function of which is described
hereinafter. The encoder is located on the rear end car 300.
Also on each of the intermediate cars and on the front end car
there is a hydraulic axle shift valve 412. The axle pivot is
controlled also by the double headed hydraulic cylinders that
is controlled by the four way - two position hydraulic valve
412. This valve has one electromagnetic solenoid 552 (see
Fig. 30) to control the flow of hydraulic fluid to the
pivoting cylinders. When no power is applied to the hydraulic
valve, the axle will lock 90~ to the forward (toward loading
car) frame and be in the correct geometry for for~ard travel.
When power is applied to the solenoid, the axle will pivot and
lock 90~ to the reverse (toward unloading car) frame and be in
the correct geometry for reverse travel. The axles must be
steered such that they are strai~ht prior to pivoting or the
tires will skid and will prohibit the axle from pivoting
easily.
Mounted on the front end car is a 25 horsepower,
.
1800 rpm, 575 volt electric motor 414 which is used to drive
the main hydraulic pump 416 for the mobile conveyor.
It will be understood that the sensor 408 is an LDT
and operates in the manner described above. Another suitable
form of LDT is that made by Balluf, Part No. BTL-E160305--Z-S32
provided with a BKS-S33-00 connector. The preferred form of
~ ~7~43 ~;
- 36 -
distance measuring device for the mobile conveyor of this
invention is the optical incremental encoder 410. One
suitable form of this encoder is that manufactured by Allen
Bradley, Model No. 845N-SJDN2-C~NI, which encoder has two
channel outputs in quadrature and counts at a rate of 500 per
revolution of the encoder shaft. This encoder is connected to
the input pinion shaft of the rear end car and is able to
measure the distance travelled by the amount of rotation of
the drive system by measuring the number of clicks produced.
The cables illustrated in Figure 25 include main
power buss 418 carrying 600 volt power, a PLC communication
cable 420 and a third cable 422 which carries the 4 to 20
milliamp signals from the transducers (LDT's). A further
cable 424 comprises two pairs of wires and leads from each LDT
to the intermediate control enclosure 40~. One pair of wires
provides power to the LDT while the other pair carries signals
from the LDT to the control enclosure. Cable 426 connects
: .
each intermediate control enclosure to the two solenoids which
operate the respective hydraulic steering valve 406. A
further cable 428 connects each control enclosure to its
respective wheel drive motor and provides 600 volt power
thereto. A further cable 430 connects each intermediate
control enclosure to its respective hydraulic axle shift valve
providing power thereto.
The main disconnect enclosure 404 provides the means
for disconnecting from the mobile conveyor a main power supply
cable 432.
Figures 26 and 27 together provide a single line
21~7~3
- 37
power diagram illustrating how the control enclosures are
connected and some of the components in these enclosures.
Figure 26, in particular, illustrates schematically the main
disconnect enclosure 404 which, as indicated, is connected to
the main power supply cable 432 which is preferably connected
to a 100 amp circuit breaker. In the disconnect enclosure is
a manually operated main disconnect CB switch 434 which is
lockable in the off position. This adjustable circuit breaker
is set at 500 amps and has an instantaneous trip. This switch
is connected to a coordinated protected starter 436. In one
preferred embodiment its thermal trip is set at 5.2 amps while
its magnetic trip is set at 70 amps. Also, in the enclosure,
is motor starter 438 and thermal overload protector 439 which
in a preferred embodiment is set at 24 amps and has a manual
reset. The motor starter 438 and protector 439 are connected
to the hydraulic pump motor 414. The switch 434 is also
connected by the main power buss at 418 to the intermediate
control enclosure 402 which supplies power to the axle at the
rear end of the front end car. The starter 436 is connected
to a relay 440 which in turn is connected to the head axle
tram drive motor 331. The purpose of relay 440 is to reverse
the connections to motor 331 when it is desirable for the
vehicle to tram in reverse. It is programmed to change state
0.5 sec. before CPS 436 changes state and thus the relay will
not make or brea~ load currentO Connected to the switch 434
by line 442 are two 15 amp fuses 444 and a transformer 446
which converts the 600 volt current to 120 volt AC, single
phase. The output of this transformer is connected to a third
~ . . ... .. ... . .
" 21~7~ll3
- 38
fuse 448 which is a 1.6 amps time delay fuse. This fuse is
connected by line 449 to the other electrical control
e~uipment in this enclosure as illustrated in Figure 31
described hereinafter.
Turning now to Figure 27, there is illustrated a
typical intermediate control enclosure 402 and some of the
components therein. Connected to the main power buss 418 are
two 15 amp fuses 450 which in turn are connected to
transformer 452 which is similar to transformer 446. The
output of the transformer is connected to fuse 454 which also
is a 1.6 amp time delay fuse. This fuse is connected by line
455 to the other control components in the enclosure which are
illustrated in Figure 30. Also contained in enclosure 402 and
connected to the power buss is a coordinated protected starter
456 which is similar to CPS 436 and has its trips set at the
same setting. The starter is connected to a relay 458 which
is ln turn connected to tram drive motor 331.
Also shown in Figure 27 is main control enclosure
400 which is located on the loading car. The power line 418
extends to this enclosure and connects up to two 15 amp fuses
460 which in turn are connected to transformer 462. This
transformer operates at 750 VA and coverts 600 volt current to
120 volt alternating current, single phase. It is connected
to a fuse 464 which is a 6.25 amp time delay fuse. This fuse
is connected by line 465 to the other electrical control
components in the enclosure which are illustrated in Figures
28 and 29. Also located in the main control enclosure is a
coordinated protected starter 466 which is similar to CPS a56.
2~ ~7~3
- 39
The starter is connected to relay 468 which in turn is
connected to the tram drive motor 331 for the tail axle of the
rear end car.
Turning now to Figures 28 and 29 which illustrate in
more detail the contents of the main control enclosure 400,
the line 465 is connected to a 24 volt DC, 4.8 amp regulated
power supply 470 which provides power through output line 472
to the controls ~or the rear end car. The line ~72 is also
connected to another power supply 474 which can be an Allen
Bradley 1771-P5 slot power supply. The controls include a
circuit breaker auxiliary contact 476 (shown reset) which is
part o~ a coordinated protected starter. If it is tripped, it
will indicate to the PLC that it is tripped. Also connected
to line 472 is an overload auxiliary contact 478 which is
shown reset and which will indicate if the overload is
tripped. There is an emergency push button stop 48~ which is
normaLly closed and a manual steering selector switch 482
which is used to steer the loading car manually. This is a
three position switch with a spring return to center position.
Also provided is a manual tramming selector switch 484 which
permits manual actuation of the wheel drive of the rear end
car (without having to move the whole conveyor train). The
switch 484 is also a three position switch with a spring
return to center. Also provided is a control selector switch
486 which can be illuminated. This switch permits one to
choose between manual and auto control. The manual switches
will operate only when the switch 486 is in the manual mode.
The next control switch is a hydraulic start switch
"~ ,,," : ~ "~
-- 21~78~3 : ~
- 40
488 which is used to actuate -the motor starter for the main
hydraulic pump providing hydraulic pressure for the whole
conveyor system. This can be a push button, normally open
switch. Next to this is a hydraulic stop switch 490 which de~
activates the motor starter and which can be a push button,
normally closed switch. The r~m~;n;ng controls connected to
line 472 are located on operator control pendant 256 indicated
by the dashed line. This pendant is preferably attached by an
electrical umbilical cord to the enclosure 400. As part of
the control pendant there is selector switch 492 which is used
to select the location for the control of the mobile conveyor,
this location being either from the rear end car or the front
end car. Also, on the control pendant is a joystick indicated
at 494 which has a spring return to center position. By means
of the joystick one can cause the mobile conveyor to tram
forward or tram reverse and one can cause the wheels of the
tail axle to steer right or steer left. These various
operator switches are connected up to DC input module 496
which can be an Allen Bradley 1771-IBN 32 point module, in
which case only the first half of the module need be used for
present purposes. This module is electrically connected as
shown to a 32 point DC output module 498 which can be an Allen
Bradley 1771-OBN module. Electrically connected to this
output module is one half of a Potter and Brumfield 2IO-16B
optoisolator board indicated by the dashed line at 500. Also
connected to the output module is a relay 502 that is used in
the reversing of the tram direction and a tail car manual
control indicator light 504 which blinks red when the car is
21~78~3
- 41
operating manually. This is a pilot light located on the rear
end car as are the other illustrated pilot lights shown in
Figure 28. The light 506 lights up red to indicate that the
emergency stop is on. Light 508 is red to indicate if any
intermediate vehicles are in manual mode while light 510
indicates that the hydraulics overload has tripped. The red
light at 512 comes on when any of the tram overloads have
tripped, whether they be thermal or magnetic, thus indicating
a problem with a tram motor starter. The green light at 514
comes on when the hydraulics are operating.
Connected to the optoisolator board 500 is the motor
starter for the tail axle. Also connected to this board are
the two solenoids which operate the hydraulic steering valve
406 for the wheels of the tail axle. These solenoids are
mounted on the valve manifold. The purpose of the board 500
is to allow output modules 24 VDC control signals to switch
120 VAC to the coils of the above components. The steering
angle of the axle is controlled by a simple hydraulic power
means controlled by the four way, three position hydraulic
valve 406. This valve has the two electromagnetic solenoids
to control the flow of hydraulic fluid to the steering
cylinder. When no power is applied to either solenoid the
wheels are locked in whatever position they are in. When
power is applied to one solenoid, the wheels will be steered
in one direction and when power is applied to the other
solenoid, the wheels will steer in the other direction. At no
time is power ever applied to both solenoids.
Figure 29 illustrates the r~m~; n; ng electrical
-~ 21~7~'~3
- 42 -
control components in the main control enclosure. The 120
volt line 465 is connected to a regulated power supply 516
which provides 5 volt direct current, 1.2 amps power. This
power supply is connected by line 518 to the aforementioned
optical incremental encoder 410 which in turn is connected to
an encoder/counter module 520 operating in encoder mode. In
the preferred embodiment this is a module available from Allen
Bradley, Model 1771-IJ. The module is mounted in the PLC rack
and feeds the distance travelled signal to the PLC. This
module 520 maintains a pulse count in its memory that the PLC
processor can access. The count value is incremented as the
train of vehicles move in the rearward (toward loading car)
direction and based on the quadrature information from the
encoder decrements the count value as the train of vehicles
move in the reverse ~toward unloading car) direction. The
processor can also send a signal to the encoder module that
will cause it to reset its coun~ value to zero. If the count
value reaches 4095 counts when counting up, the counter will
wrap around to 0 and continue counting up from 0 to 4095
again, likewise if the count value reaches 0 when counting
down the count value wil~ wrap around and begin counting down
from 4095. Electrically connected between the incremental
encoder and the module 520 is one-third of a 7404 hex inverter
indlcated at 522. This is a digital chip to invert the
digital signal and is only used if inversion is re~uired.
Also shown in Figure 29 is analog input module 524
which can be that made by Allen Bradley, Model 1771-IFE,
suitable for 4-20 ma differential inputs. Connected to this
- ''' 2lf~f~f8~3
- g3
module is electrical control cable 526 which can be a Belden
9332 cable containing nine pairs of wires. These wires are
connected up to the various intermediate control enclosures
402 and they provide the electrical signals from the various
LDT's, to the module 524. The signals from the transducer for
the rear end car axle are fed through wires 527 and 528. The
axle position sensors or LDT ' s are connected to the analog
input module using one channel per axle. This module converts
the incoming 4-20 ma signal from each axle LDT to a decimal
value that the processor can access. The LDT's are calibrated
so that the output value will be 0 when the axles are steered
all the way in one direction and 3100 when the axles are
steered all the way in the other direction. This value
indicates to the processor at what angle the wheels are
steered with a value of 1550 indicating the wheels are
straight.
Figure 30 illustrates the electrical components in
the typical intermediate vehicle control enclosure 402. Line
455 is connected up to a regulated power supply 530 providing
24 volt DC current at 1.2 amp. The output line 531 of this
power supply is connected to several switches including an
emergency stop switch 532, a manual steering switch 534, a
manual tramming switch 536 and a control switch 538. These
switches are similar to those found in the main control
enclosure. There is also connected to the line an overload
auxiliary contact 540 shown as reset and a circuit breaker
auxiliary contact 542, also shown reset. These components and
switches are connected to an Allan Bradley 1791-IOBB block
.
2~f78/13
- 44
input/output module 544. This module is connected to an
optoisolator board 546 outlined in dashed marks. A suitable
board is that made by Potter and Brumfield, Model No. 2IO-4B.
One output line from this board is connected to the hydraulic
tram motor 331 for the respective intermediate car. Further
output lines are connected to two solenoids indicated at 548
and 550 which are used to control the hydraulic valve that
acts to steer the wheels of the car. There is also a third -
solenoid 552 for operating the double headed cylinders.
Also connected to module 544 on the output side is
a relay 554 for tramming in the reverse direction. There is
also a manual control indicator at 555 in the form of a pilot
light which blinks red when the car is operating manually.
Connected to one end of the 24 volt line is the linear
displacement transducer 218 for the intermediate car. This
transducer is also connected to two wires 556 and 557 which
; connect u~ to the control cable 422. -
Figure 31 lS a schematic illustration of many of the
components in the main disconnect enclosure 404. Electrical
line 449 is connected to a 24 volt direct current, 1.2 amp
regulated power supply 560. Its 24 volt line 562, as in the
other enclosures, is connected to a number of control switches
,, I j :-,
including an emergency stop switch 564, a manual steering
switch 566, a manual tramming switch 568 and a switch 570 for
selecting between manual and auto control. There is also a
hydraulics start switch 572 and a hydraulic stop switch 574.
Also, connected to this line is an overload auxiliary contact
576 shown in the reset position and a circuit breaker
, : , , ~ , . . .
--' 2~7~3
- 45
auxiliary contact 578 shown reset. These switches are
connected up to an Allen Bradley 1791-IOBB block I/O module
580. A number of output lines from this module are connected
to an optoisolator board 582 which can be one-half of a Potter
and Brumfield 2IO-16B board. Connected to the optoisolator
board is a tram drive motor 331 for the head axle, that is the
axle at the front of front end car 304. There are also
connected to this board two solenoids which operate the
hydraulic valve for steering the wheels mounted on the head
axle. An electrical line 584 connects board 582 to the
electric motor 414 which drives the hydraulic pump for the
conveyor. Also connected to module 580 is the aforementioned
two wire cable 420 which is the PLC communication cable and
which extends to the next car. The same connectors on the
board 580 as are connected to cable 420 are connected to a
second Allan Bradley 1791-IOBB block I/O module 586 by line
588. This module is also connected to the 24 volt line 562.
To this module is connected an overload (shown reset) 590 and
the electrical connections for operator control pendant 592.
The overload is shown in the non-tripped position and, if
tripped, it would be open. As with the other control pendant,
the pendant 192 provides by means of a joystick a control for
tramming forward or in reverse and for steering the wheels on
the head axle either right or left. Connected to the output
of module 586 is a relay 592 that allows tramming of the head
axle in reverse, a manual control indicator 594 and a control
active indicator (green light) 596 that is located on the
operator control pendant. These indicators are connected to
~' ' ' ':: . ' '''' ' :' ' ', . :. ' . . . " . '
: :.:' :' ': ' ; . '', ' ' . . ~ : ' . ' ' ' ' . '
-- 2~7~3
- 46
electrical line 598 which also connects up to the linear
transducer 408 for the head axle. Also connected to this
transducer are two control wires 599 and 600 which connect up
to the cable 422 which connects to the first in line -
intermediate vehicle control enclosure 402.
Located also in the main control enclosure is the
processor or PLC which can be an Allen Bradley PLC 5/30. This
processor is connected to the first intermediate control
enclosure 402, that is the one on the rearmost intermediate
car. It is connected to the intermediate closure by means of
the cable 420 (see Figure 25).
In the analog input module 524 all ~h~nnels are set
for differential current input. -
The software program that operates the preferred
embodiment of the mobile conveyor illustrated in Figures 18 to
31 is based on the Allen Bradley 6200 series PLC 5 software
and it is designed to operate the aforementioned Allen Bradley
PLC 5/30. The program set out hereinafter is for a four axle
conflguration (for instance, the four axles shown in Figure
25) and is based on a total train or conveyor lenyth of 60
feet so that the distance between axles is 20 feet or 240
inches. The program is further based on a tire diameter of 26
,
inches which corresponds to a tire circumference of 81.6814
inches and an axle gear ratio (wheel rev: pinion shaft rev.)
of 1:3.07. Thus one revolution of the pinion shaft results in
26.6063 inches of travel of the train of vehicles. In this
example, a steering correction is made every ten inches of
linear travel of the train and this will translate to 200
-'~ 2~7~3 :
- 47
encoder pulses. This implies that the encoder must be
coupled to the pinion shaft at a ratio (pinion shaft rev~
encoder shaft rev:) equal to
10/26.6063 = 0.9396
200/500
This is accomplished in a manner known per se by using two
pulleys of different diameter so that one revolution of the
encoder will indicate 25 inches of travel and, for example,
2/5ths of a revolution will indicate 10 inches of travel.
In the software program, a data table is set up to
store axle position values in decimal form (0-3100). This
table is retentive (when power is shut off, values remain).
The data table length is determined by the total length of the
train, the number of axles, and the desired distance between
steering corrections.
In this example, the data table starts at integer
file posltion N13:11 and uses 70 positions (words) in the
table through to N13:81. Each axle is initially assigned a
pointer value which is also stored in retentive memory. These
pointers are, in the example, 23 memory locations apart from
each other, since the axles are 240 inches apart and
correction is made every ten inches. The pointer is used in
indexed addressing to point to a location in the data table
that the axle should either store its current value or move to
the position indicated in the table. The pointer value for
each axle is incremented every time the encoder/counter module
accumulated count increases by 200 counts (10 inches of travel
forward) and decremented every time the encoder/counter module
,'.'~. ''
~.
- 2~78~3 ~
- 48
accumulated count is decremented by 200 counts (10 inches of
travel reverse).
In one embodiment, the pointer for the loading car
axle is stored in memory location N13:1, the second axle in
N13:6, the third axle in N13:7 and the leading axle of
unloading car in N13:8. The initial values stored are 70, 47,
24, 1 respectively. The pointer values wrap, i.e., if a
particular pointer value increases to 71, it is reset back to
1. If a particular pointer value decreases to 0 it is rest to
70. On first start up, a number of 1550 should be stored in
all memory locations so the trailing axles will follow a
straight path until fresh information of the leading axle is
moved into memory.
A control loop for each axle is set up using the
processors PID command. The axles position sensor forms a
value that is fed back lnto the PID equation as its process
value or PV. The PID equation executes continuously if it is
enabled and outputs a control value or CV based on the set
point SP and the process value. For the hydraulic valve
selected, the control value is converted to a time
proportionéd output to drive either the steer left or steer
..
right solenoid valves based on whether the process value (axle
position) is above or below the commanded value or set point.
This control loop is tuned manually until smooth response of
the steering system occurs in response to a change in the
setpoint and desired accuracy is obtained.
Further accuracy could be obtained by using a servo
type hydraulic valve to control the steering, however, this
--' 21~78~3
- 49 -
adds cost to the system. The PID control loop of all of the
intermediate axles is always enabled and the hydraulic system
will keep the axle in the position commanded ~y the setpoint,
unless the axle control is switched to manual at an
intermediate control box at which time the manual steer
left/right switch signals are directed to the solenoid valves.
Automatic control of the train of vehicles is
initiated via the operator control pendant which is at the end
of the train closest to the desired direction of travel. When
the unit is stationary and the hydraulic pump has been started
and no faults such as overload or emergency stops have been
detected, the unit is ready for operation in either direction.
The switch on the loading car operator control pendant is set
to the desired control location activating either the loading
car pendant or unloading car pendant. Prior to and during
tramming of the train the operator can steer the end axle
closest to him to any desired position. If the operator moves
the joystick to the tram forward position the program
determines whether the axle pivot solenoid valve is de-
energized (correct position for forward travel) if it is nota value of 1550 (axle straight) is sent to the setpoint of the
-
PID equation for the particular axle causing the wheels to
straighten.
When the wheels are acceptably straight the solenoid
for axle pivot is de-energized causing the axle to pivot to
the correct position for forward travel. At the same time
that tram forward is selected, an internal timer is activated
(5 seconds in one embodiment) to delay startup of the tram
~ 2~7~
- 50
motors to allow time for an alarm to sound prior to tramming
and to allow time for the axles to pivot to the correct
position prior to movement of the train.
The same operation occurs if tram reverse is
selected except that the solenoid is energized if it was de-
energized to pivot the axle to the correct position for
reverse steering.
When this pivoting of axles occurs, it must be
realized that the end car in the direction of travel is now
effectively a four wheeled rigidly connected car with both
axles parallel to each other. Since the operator needs to be
able to effectively steer this end car, the wheels on one axle
must counter steer the wheels on the other axle about a
centerline perpendicular to both axles. At the commencement
of tramming (after the 5 second delay), the value read from
the end car axle position transducer is subtracted from 3100
and the resulting value is placed as the setpoint to the PID
equation for the second axle in toward the middle of the
train. This process is continuous during tramming for the
leading four wheeled car with the operator controlling the
leading axle manually with the joystick and the trailing axle
of the four wheeled car following a counter steered path. At
I . ~ I . ~
the same time data from the leading axle and trailing axle of
the four wheeled car is being stored into memory locations in
the data table pointed to by their respective axle pointers.
At the same time the other trailing axles of the train are
reading the values in the data table locations pointed to by
their respective pointers and moving this value to the
:~ ~ . . ;.: . ,
,., :: , : ~ ~ , : . ,:
~ . . ~ . ~ . . .
--' 2~7~3
- 51
setpoint of their PID equations. From this it can be seen
that all of the trailing axles follow a path that the trailing
axle of the four wheeled lead vehicle has followed. In the
reverse direction the process reverses itself.
Another feature is that if any of the axles trailing
the lead axle are switched into manual during tramming, the
value of the position transducer of the particular axle
overwrites data in the data table at the location pointed to
by its pointer. This allows all of the following vehicles to
make the same correction that was made manually at a certain
position along the train. This is useful if material has
fallen down off of a mine wall after the lead vehicle has
passed the location where the fall has occurred.
Various modifications and changes to the steering
system as described will be apparent to those skilled in this
art. All such modifications and changes as fall within the
scope of the appended claims are intended to be part of this
invention.
. ~
, ~'"'
