Note: Descriptions are shown in the official language in which they were submitted.
CA 02286949 1999-10-18
BULLDOZERlPIPELAYER COMBINATION
FIELD OF THE INVENTION
This invention relates generally to apparatus attached to a tracked
vehicle for lifting, transporting and laying pipe and is particularly directed
to a
bulldozerlpipelayer combination having a folding boom and a pair of track
roller
frames which oscillate when operated in the bulldozer mode and are locked in
a fixed orientation when the apparatus is used in pipelaying.
BACKGROUND OF THE INVENTION
A common approach for laying pipe employs a diesel powered tracked
vehicle having a side boom for lifting, transporting and positioning the pipe
in or
~ o on the ground. The tractor, which frequently is in the form of a
bulldozer,
includes a primary closed, pressurized hydraulic system for bulldozer
operation
and a secondary hydraulic system coupled to the first primary system for
pipelayer control. The tractor travels generally parallel with the pipeline,
with
its offset position from the pipeline determined by operating conditions and
the
i 5 size and characteristics of its side boom.
The typical bulldozer includes a front blade or scoop for moving soil or
heavy objects and a pair of side-mounted track roller frames each supporting a
respective endless track for propelling the bulldozer. The track roller frames
are attached to the bulldozer's main frame in a pivoting manner which allows
2o the track roller frames to oscillate up and down about a horizontal axis
passing
through the main frame. The vertical displacement of the forward and aft
CA 02286949 1999-10-18
2
portions of each of the track roller frames as the bulldozer traverses
irregular
terrain provides better traction and grading characteristics, as well as a
more
comfortable ride for the operator. When a pipelayer is attached to the
bulldozer and used in the laying of pipe, the vehicle's main frame is
positioned
to the side of the pipe which is maneuvered into position as the vehicle moves
forward. In a conventional pipelayer, the track roller frames are rigidly
attached
to the vehicle's main frame and are not free to pivot in an oscillating
manner.
This provides the pipelayer attachment with a more stable platform for lifting
and transporting heavy loads, but limits the use of the tracked vehicle as a
i o bulldozer because the track roller frames are locked in a fixed position
on the
vehicle's main frame.
A pipelayer attachment typically includes a boom structure pivotally
attached to one of the track roller frames of the tracked vehicle and
extending
to one side of the vehicle. A boom and load winch combination allows the
i s boom structure and a load supported by the boom structure to be raised or
lowered. When retracted for transport or storage, the boom structure assumes
a generally vertical orientation and extends well above the height of the
tracked
vehicle. This limits where the tracked vehicle may be transported and stored.
In order to avoid this problem, the boom structure is sometimes removed from
20 the tracked vehicle frame for transport andlor storage, but this removal
and
subsequent reattachment is cumbersome, time consuming and requires
several workers. In addition, when the tracked vehicle is used as a bulldozer,
the retracted or upraised boom structure limits where the bulldozer can be
operated.
CA 02286949 1999-10-18
3
The present invention addresses the aforementioned limitations of the
prior art by providing a bulldozerlpipelayer combination incorporating a
folding
boom structure which can be extended for use or retracted for transport,
storage or when bulldozing to a compact configuration disposed in closely
spaced relation to the tracked vehicle by the vehicle operator using pipelayer
boom and load controls. The bulldozer's oscillating track roller frames are
automatically locked in fixed position on the vehicle's main frame for use in
the
pipelaying mode by the operator.
i o OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a
bulldozeNpipelayer combination that is equally adapted for grading and earth
moving as well as for lifting and transporting heavy loads when used in
pipelaying.
It is another object of the present invention to provide in a bulldozer with
a pipelayer attachment a selectable control for allowing the bulldozer's track
roller frames to oscillate up and down when used as a bulldozer, or for
locking
the track roller frames in fixed position when operated in the pipelayer mode
to
provide a stable platform for lifting and transporting heavy loads.
Yet another object of the present invention is to provide a folding boom
for a pipelayer attached to a tracked vehicle which can be moved between a
folded and an extended position by the vehicle operator using controls
employed in the operation of the pipelayer.
CA 02286949 1999-10-18
4
A further object of the present invention is to provide a folding pipelayer
boom attached to the side of a tracked vehicle which when retracted allows the
tracked vehicle to operate in low, narrow areas and permits tracked vehicle
transport and storage without removing the boom.
s A still further object of the present invention is to provide improved load
control in a pipelayer attached to a tracked vehicle such as a bulldozer by
rendering the pipelayer's boom and load winches equally responsive to
hydraulic control inputs.
This invention contemplates a bulldozer/pipelayer apparatus comprising
i o a main frame incorporating an engine for driving the bulldozerlpipelayer
combination; first and second track roller frames each coupled to a respective
lateral portion of the main frame and including a respective segmented,
endless track for displacing the apparatus; a boom winch having a boom cable
dispose thereabout and a load winch having a load cable disposed thereabout;
and a folding boom having first and second frames pivotally coupled together,
wherein the first frame is pivotally coupled to the first track roller frame
and the
second frame is coupled to the boom cable for raising and lowering the boom
and is further coupled to the load cable for raising and lowering a load, and
wherein the boom is adapted for movement between an extended, use
20 configuration for raising and lowering a load wherein the first and second
frame are in generally linear alignment and a folded configuration for storage
or transport wherein the first and second frames are aligned generally
transverse and are each disposed in closely spaced relation to a side of the
apparatus.
CA 02286949 1999-10-18
BRIEF DESCRIPTION OF THE DRAWINGS
The appended claims set forth those novel features which characterize
the invention. However, the invention itself, as well as further objects and
advantages thereof, will best be understood by reference to the following
5 detailed description of a preferred embodiment taken in conjunction with the
accompanying drawings, where like reference characters identify like elements
throughout the various figures, in which:
FIG. 1 is a perspective view of a bulldozerlpipelayer combination in
accordance with the principles of the present invention showing the pipelayer
i o boom in the extended position;
FIG. 2 is a perspective view of the inventive bulldozer/pipelayer
combination showing the pipelayer boom partially retracted or folded;
FIG. 3 is a perspective view of the inventive bulldozerlpipelayer
combination showing the pipelayer boom in the fully retracted or folded
position;
FIG. 4 is a partial perspective view of the side of the bulldozerlpipelayer
combination of the present invention illustrating details of the manner in
which
the pipelayer's boom is connected to one of the vehicle's endless track roller
frames and the manner in which the pipelayer's left support structure is
attached to the vehicle's main frame independent of the track frame;
FIG. 5 is a simplified sectional view of an arrangement for preventing the
vehicle's track roller frames from oscillating when used in a pipelaying mode
in
accordance with one aspect of the present invention;
CA 02286949 1999-10-29
J
6
FIGS. 6 and 7 are simplified sectional views of the track roller frame
mounting arrangement of the present invention showing the track roller frames
free
to oscillate relative to the vehicle's main frame when the vehicle is used as
a
bulldozer by means of an equalizer bar in accordance with another aspect of
the
present invention;
FIG. 8 is a partial perspective view showing the location of a lockout
cylinder assembly mounted to a lateral portion of the vehicle's main frame
engaging
an equalizer bar;
FIGS. 9a, 9b and 9c are a schematic diagram of the hydraulic control
system used in the bulldozer/pipelayer combination of the present invention;
FIG. 10a is a simplified block diagram of a prior art load winch drive
train such as used in a conventional pipelayer;
FIG. 10b is a simplified block diagram of a load winch drive train
incorporated in a pipelayer in accordance with the present invention; and
FIG. 11 is a longitudinal sectional view of the inventive load winch drive
train shown in FIG. 10b in simplified block diagram form.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, there is shown a perspective view of a
bulldozer/pipelayer combination 10 having a pipelayer attachment 12 in
accordance
with the present invention. The bulldozer/pipelayer combination 10 of the
present
invention includes a conventional tractor having a main frame 22 and left and
a right
track frames, where the left track frame is shown as element 20 in FIG. 1. The
designations "right" and "left" are taken with the bulldozer/pipelayer
combination 10
viewed from the rear. Disposed on the right and left track frames are
respective right
and left segmented, endless tracks 14 and 18. The tractor includes an engine,
which
is typically of the diesel type, in its main frame 22 and further includes a
blade 16
attached to the main frame by means of left and right mechanical linkages,
where the
left mechanical linkage is shown as element 30 in FIG. 1. Mechanical linkage
30
CA 02286949 1999-10-18
7
is coupled to a left hydraulic cylinder 26 by means of left pivot bracket 28.
A
similar hydraulic cylinder, pivot bracket and mechanical linkage combination
is
disposed on the right side of the main frame 22 and is also connected to blade
16, although this is not shown in the figure for simplicity. Blade 16 is
raised or
lowered by the pair of hydraulic cylinders for displacing soil or heavy
objects.
The hydraulic cylinders are energized by the tractor's hydraulic system. A
tractor having a movable blade 16 as shown in FIG. 1 is commonly known as a
bulldozer. An operator of the bulldozerlpipelayer combination 10 sits on an
upper, aft portion of the main frame 22 beneath a cover or canopy 32.
~ o Attached to the left track frame is a pipelayer attachment 12 which
includes the generally "A" shaped boom 48. Boom 48 includes first and
second lower frame members 48a and 48b and first and second upper frame
members 50a and 50b. Respective lower ends of the first and second boom
lower frame members 48a,48b are connected to forward and aft track frame
i 5 brackets 36 and 38. The forward and aft brackets 36,38 are attached to the
tractor's left track frame 20, with each bracket including a pair of aligned
apertures. Inserted through the aligned apertures of the forward bracket 36
and through an aperture in a lower end of the first boom lower frame member
48a is a first boom pivot pin 40. Similarly, inserted through the aligned
20 apertures of the aft bracket 38 as well as through an aperture in the lower
end
of the second boom lower frame member 48b is a second boom pivot pin 42.
The first and second pivot pins 40,42 allow the boom 48 to be raised and
lowered in a pivoting manner as described below. Boom 48 in FIG. 1 is shown
in a substantially, although not fully, upraised position. Lower and upper
cross
CA 02286949 1999-10-18
8
members 54 and 55 are disposed between and attached to the first and
second boom lower frame members 48a,48b for increased strength and
rigidity.
Attached to the respective upper ends of the first and second boom
lower frame members 48a,48b are the first and second boom upper frame
members 50a and 50b. The first upper and lower frame members 48a,50a are
pivotally coupled together by means of a first hinge 52a. Similarly, the
second
lower and upper frame members 48b,50b are pivotally connected together by
means of a second hinge 52b. One or more cross members 56 are connected
~ o between the first and second hinges 52a,52b adjacent the lower ends of the
first and second upper frame members 50a,50b for increased strength and
rigidity. The first and second hinges 52a,52b allow the upper and lower
sections of the boom 48 to pivot relative to one another as shown in the
perspective view of FIG. 2 illustrating the boom in a partially folded
configuration.
When the upper and lower frame members of the boom 48 are aligned
and the boom is fully extended as shown in FIG. 1, aligned apertures in the
first and second hinges 52a,52b are adapted to receive respective first and
second boom elbow locking pins 46a and 46b for securely locking the boom in
20 the extended configuration. In order to fold the boom 48, the first and
second
locking pins 46a,46b must first be removed from the aligned apertures in the
first and second hinges 52a,52b. One of these aligned apertures in the first
hinge 52a is shown as element 44a, while one of the apertures in the second
hinge 52b is shown as element 44b in FIG. 2. In FIG. 2, the locking pins have
CA 02286949 1999-10-18
9
been removed from the aligned apertures in the hinges to allow the boom to
fold as shown in this figure. A pair of pivot stops are attached to the lower
ends of the first and second upper frame members 50a,50b to limit the extent
of folding of the upper and lower boom sections. One of these pivot stops is
shown in FIG. 1 as element 24 mounted to the lower end of the first boom
upper frame member 50a for engaging the first hinge 52a in limiting pivoting
displacement of the boom's upper frame on its lower frame. Also attached to
the lower end of the boom's upper frame is a stowing bracket 43 which is used
in folding the boom 48 as described in detail below for transport or storage
of
~ o the bulldozeNpipelayer combination 10. Attached to the distal, or upper,
end of
boom 48 is a first trunion 66. Attached to the first trunion 66 is a load
block 60.
Also attached to the distal end of the boom 48 is a second trunion 67.
Attached to the second trunion 67 is a boom block 58. The first and second
trunions 66,67 allow the load and boom blocks 60,58, respectively, to move
inward and outward and also to pivot about a vertical axis passing through
each block. Suspended from the load block 60 by means of a cable is the
combination of a hook block 62 and a hook 72. Attached to and suspended
from the hook 72 is a load 64 shown in dotted line form.
Attached to respective sides of the tractor's main frame 22 are left and
20 - right support frames 74 and 78. The left and right support frames 74,78
are
attached to respective sides of the main frame 22. The left support frame 74
is
attached to the left side of the main frame 22 by means of the combination of
a
support arm 86 and a mounting flange 88 as shown in FIG. 4. The lower end
of support arm 86 is secured to mounting flange 88 such as by welding.
CA 02286949 1999-10-18
l0
Mounting flange 88, in turn, is securely mounted to the left side of the main
frame 22. The left and right support frames 74,78 are also connected together
by means of a cross member 34 disposed above and extending across the
tractor's main frame 22. The left and right support frames 74,78 are thus
connected to and supported only by the tractor's main frame and not by the
left
and right track frames as well as by the main frame as in prior approaches.
Attaching the support frames to the tractor's track frames as well as to its
main
frame as in the prior art resulted in movement of the support frames as the
track frames pivoted when in a bulldozer mode of operation. This arrangement
i o produced unwanted displacement of the support frames and pipelayer
components attached thereto and damaged the support frames.
Attached to and supported by the right support frame 78 are boom and
load winches 80 and 82. Disposed about the boom winch 80 is a boom cable
68 which is inserted through the boom block 58. An end of the boom cable 68
is securely attached to the left support frame 74 by means of a cable
terminator 76. The boom 48 of the pipelayer attachment 12 is raised by
rotation of the boom winch 80 in a first direction so as to retract the boom
cable 68. Rotation of the boom winch 80 in a second, opposed direction
allows for lowering of the boom 48. A load cable 70 is disposed on the load
20 winch 82. The load cable 70 extends from the load winch 82 above the main
frame 22 to a pulley (not shown) in the left support frame 74 and then through
the load block 60 to the hook block 62. Rotation of the load winch 82 in a
first
direction so as to retract the load cable 70 causes the load 64 to be raised.
Rotation of the load winch 82 in a second, opposed direction allows the load
CA 02286949 1999-10-18
11
cable 70 to be withdrawn from the winch and the load 64 to be lowered.
The procedure followed in folding the boom 48 of the pipelayer
attachment 12 from the extended configuration shown in FIG. 1 to the folded
configuration shown in FIG. 3 is as follows. The extended boom 48 is first
s lowered to an approximately horizontal position. The lower boom section
including the first and second boom lower frame members 48a,48b is then
supported by either attaching a chain between cross member 54 and the left
support frame 74 or by positioning a block on the ground beneath the lower
boom section. Slack is then provided in the boom and load cables 68 and 70.
~ o The first and second boom elbow locking pins 46a,46b are then removed from
the respective apertures 44a and 44b in the first and second hinges 52a,52b.
The locking pins are then stored in stowing holes (not shown for simplicity)
in
the lower boom section adjacent cross member 55. The boom 48 is initially
folded using only the boom winch 80. When the upper boom section including
15 the first and second upper frame members 50a, 50b forms an angle of
approximately 90° with the lower boom section including the first and
second
lower frame members 48a,48b, the hook 72 on the hook block 62 is attached
to the stowing bracket 43 adjacent the lower end of the upper boom section.
This is shown in FIG. 2 where the upper boom section is oriented generally
20 90° to the lower boom section and the combination hook and hook
block 62 is
attached to the stowing bracket (which is not shown in the figure for
simplicity).
During initial folding of the boom as the boom approaches the position shown
in FIG. 2, the boom and load cables 68,70 are simultaneously retracted. As
the boom 48 continues to fold, the lower boom frame pivots about the first and
CA 02286949 1999-10-18
12
second pins 40 and 42 respectively inserted through the forward and aft
brackets 36 and 38. Continued winding of the boom cable 68 onto the boom
winch 80 proceeds simultaneously with continued paying out of the load cable
70 from the load winch 82 to avoid placing stress on the boom as it is folded.
Once the boom 12 reaches the position shown in FIG. 2, the load cable 70 is
paid out at the same rate that the boom cable 68 is retracted to permit the
load
cable to support and prevent the boom from falling as the boom approaches
the fully folded position. Again, sufficient slack is provided in the load
cable 70
during folding of the boom 48 to allow the load cable to follow the folding
boom
~ o as the boom passes its position as shown in FIG. 2. Once the boom 48 is in
the fully folded position as shown in FIG. 3, the distal end of the upper
frame of
the boom may be secured to the right support frame 78 by means of a chain
which is not shown in the figure for simplicity. Sufficient stack must be
provided for in the chain to allow for vertical oscillation of the left track
roller
1 5 frame as the bulldozerlpipelayer combination is used in the bulldozer
mode.
The boom 48 is moved from the fully folded position shown in FIG. 3 to
an extended position as shown in FIG. 1 using the following procedure. First,
a support or block (not shown in the figures for simplicity) is positioned on
the
ground adjacent the left side of the bulldozer/pipelayer combination 10.
20 - Alternatively, a chain (also not shown in the figures) may be attached to
the left
support frame 74. If a stowing chain is connected between the upper end of
the boom 48 and the right support frame 78, this chain is removed. The boom
48 is unfolded initially using the load winch 82. The load cable 70 is drawn
onto the load winch 82 while the boom cable 68 is paid off of the boom winch
CA 02286949 1999-10-18
13
80, maintaining sufficient slack in the boom cable so that it closely follows
the
unfolding boom 48. After the upper folded boom section goes over center
under the influence of the retracted load cable 70, the boom cable 68 will
support the folded boom as shown in FIG. 2. To further unfold the boom 48,
the boom cable 68 is slowly paid off of the boom winch 80 allowing the folded
boom to be pulled downwardly under the influence of gravity. The load cable
70 is simultaneously allowed to pay off of the load winch 82 so that the load
cable slowly follows the unfolding boom. The boom 48 is allowed to continue
to unfold until the lower boom section rests upon the aforementioned support
~ o block or is supported by a chain attached to the left support frame 74,
followed
by alignment of the boom's upper section with its lower section, with the
extended boom then assuming a generally horizontal orientation. The first and
second boom elbow locking pins 46a and 46b are then respectively inserted in
apertures 44a and 44b in the first and second hinges 52a and 52b to lock the
boom's upper and lower sections in rigid connection. The boom 48 may then
be raised by drawing the boom cable 68 onto the boom winch 80.
Another aspect of the present invention involving the side-mounted track
frames of the bulldozerlpipelayer combination will now be described with
respect to FIGS. 5, 6 and 7 which are simplified sectional views of a track
20 - frame installation in accordance with this aspect of the present
invention.
These figures show the inventive track frame arrangement 90 which includes
an elongated equalizer bar 96 attached to a lower portion of the tractor's
main
frame 92 by means of a pivot pin 94. The equalizer bar 96 is oriented
lengthwise transverse to the longitudinal axis of the tractor's main frame and
to
CA 02286949 1999-10-18
14
the direction of travel of the tractor. Pivot pin 94 allows the equalizer bar
96 to
be pivotally displaced with respect to the tractor's main frame 92. Mounted to
a first end of the equalizer bar 96 by means of a first equalizer bar pivot
pin
102 is a first track roller frame 98. Attached to a second, opposed end of the
s equalizer bar 96 by means of a second equalizer bar pivot pin 104 is a
second
track roller frame 100. The first and second track roller frames 98,100 are
disposed adjacent respective sides of the tractor's main frame 92 and are
aligned lengthwise along the tractor's direction of travel. Each of the track
roller frames engages and supports a segmented, endless track such as those
~ o shown in FIGS. 1, 2 and 3 for propelling the tractor. The first and second
track
roller frames 98,100 are free to pivot with respect to the equalizer bar 96,
while
the equalizer bar 96 is free to pivot relative to the tractor's main frame 92.
Pivoting displacement of the equalizer bar 96 and track roller frames 98,100
allows the tractor to traverse irregular terrain while allowing the tractor's
main
i 5 frame 92 to remain in a generally upright, or vertical, orientation.
Pivoting
displacement of the equalizer bar 96 and track frames and segmented,
endless tracks connected thereto provides better traction and grading
characteristics as well as a more comfortable ride for the operator when used
in a bulldozing mode of operation. The equalizer bar 96 and pivot pin 102,104
20 combination also transmits ground impact loads on the track roller frames
directly to the tractor's main frame 92, protects power train components, and
maintains the track roller frames in proper alignment. This mode of operation
is shown in FIGS. 6 and 7 where oscillating forces are shown applied to the
first and second track roller frames 98,100 causing the equalizer bar 96 to
CA 02286949 1999-10-18
oscillate in a vertical plane relative to the tractor's main frame 92
In accordance with this aspect of the present invention, first and second
lockout cylinders 106 and 108 are mounted to respective sides of the tractor's
main frame 92. This is also shown in the partial perspective view of FIG. 8
s illustrating details of the installation of the first lockout cylinder 106
which is
attached to the right side 92a of the vehicle's main frame and includes an
extendible ram (not shown in the figure). The second lockout cylinder 108 is
also provided with an extendible ram 112 as shown in FIGS. 5, 6 and 7.
Extension of the first and second lockout cylinders 106,108 causes the
~ o respective rams 110 and 112 to engage an upper portion of the equalizer
bar
96 preventing pivoting displacement of the equalizer bar about the pivot pin
94
connecting the equalizer bar to the tractor's main frame 92. The first and
second lockout cylinders 106,108 are extended for locking the equalizer bar 96
in fixed position relative to the tractor's main frame 92 when the
15 bulldozerlpipelayer combination is operated in a pipe laying mode. When the
pipelayer mode of operation is selected by means of a mode control valve
described below, the first and second lockout cylinders 106,108 extend. If the
bulldozer/pipelayer combination is on level ground, the rams of both lockout
cylinders 106,108 will each engage a respective end of the equalizer bar 96 so
as to prevent pivoting displacement of the equalizer bar. If the
bulldozer/pipelayer combination is not positioned on level ground when the two
lockout cylinders 106,108 extend, the lockout cylinder adjacent the lower
track
frame will fully extend, but will not engage the equalizer bar, while the
other
lockout cylinder will engage the equalizer bar, but will not be fully
extended.
CA 02286949 1999-10-18
16
The latter lockout cylinder will fully extend when movement of the
bulldozer/pipelayer combination causes an adjacent end of the equalizer bar to
move downward because of uneven terrain. When this occurs, the former fully
extended lockout cylinder will engage an adjacent end of the equalizer bar.
The two fully extended lockout cylinders each engaging a respective end of the
equalizer bar prevent pivoting movement of the equalizer bar. After both
lockout cylinders are fully extended, lockout valves 106a and 108a
respectively disposed in the first and second lockout cylinders 106 and 108
are
automatically actuated by a hydraulic system described below to maintain the
~ o cylinders in the extended position. With the equalizer bar 96 and
associated
track frames and endless tracks locked in fixed relative position with respect
to
the tractor's main frame, the inventive bulldozer/pipelayer combination
provides a stable platform for lifting and transporting heavy loads such as
sections of pipe. The first and second lockout cylinders 106,108 are under the
~ s control of a pipelayer hydraulic system which is described in the
following
paragraphs.
Also shown in the perspective view of FIG. 8 are a top roller 152 for the
right endless track and a roller support bracket 154 attached to the top track
roller. The right lockout cylinder 106 is shown positioned adjacent the right
20 end of the equalizer bar 96 so that its ram can engage the equalizer bar
when
in the pipelayer mode of operation. A support arm 156 mounted to the right
side 92a of the tractor's main frame is attached to and supports the
pipelayer's
right support frame which is also not shown in the figure for simplicity.
Referring to FIGS. 9a, 9b and 9c, there is shown a schematic diagram of
CA 02286949 1999-10-18
17
a hydraulic control system 116 used in the bulldozer/pipelayer combination of
the present invention for operating the pipelayer attachment. Connections
between the various hydraulic lines shown in these figures are indicated by
common letter designations in the several figures. The hydraulic system in a
s typical tractor is a parallel system wherein the flow of the hydraulic fluid
is
divided simultaneously between or among the various hydraulically actuated
components. In this type of system, the flow is greatest in the path of least
resistance, with various simultaneously actuated hydraulic components
receiving different fluid flows and experiencing different levels of
actuation.
~ o The hydraulic control system 116 shown in FIGS. 9a, 9b and 9c is a series
type of system, with the hydraulic fluid flowing from first, to second, to
third,
etc., hydraulically actuated components. The hydraulic control system 116 is
connected in series to and energized by the tractor's hydraulic system as
described in detail below. In a series-type of hydraulic system, the boom and
load winches operate at substantially the same speed when both are actuated
providing improved load control, while in a parallel type of system the boom
and load winches may operate at different speeds depending upon their
respective loading. Driving the boom and load winches in series also avoids
stalling out the more heavily loaded winch which can occur in a parallel
20 hydraulic control system.
The hydraulic control system 116 is coupled in series to a pump 118 and
a hydraulic reservoir or tank 120 which are part of the tractor's hydraulic
system. Hydraulic pump 118 is of the variable volume, pressure compensated
type. Pump 118 includes internal controls for adjusting the pump stroke to
CA 02286949 1999-10-18
18
maintain a pump delivery pressure slightly larger than the signal received
from
the load sense connection. Hydraulic reservoir 120 is of a sealed construction
with atmospheric pressure and vacuum relief and includes internal filter
elements. A valve assembly 122 is connected to the hydraulic reservoir 120
and includes an inlet cover, working sections for implement control, and an
end cover. The working sections within valve assembly 122 are arranged in
parallel, with each section providing an indication of work port pressure for
sending the highest pressure to the pump load sense connection by means of
shuttle valves. A power beyond cover 124 is coupled to the valve assembly
~ 0 122 for providing connections for the pipelayer hydraulic system which
include
a pressure line from the pump 116, a return line to the hydraulic reservoir
120
and a load sense line to a manifold assembly 132. The power beyond cover
124 also connects the pipelayer hydraulic control system 116 in series to the
tractor's hydraulic system, only a portion of which is shown in the figure for
i 5 simplicity. The manifold and valve assembly 126 operates the hydraulic
system according to command inputs from an operator. The manifold and
valve assembly 126 blocks the pump flow until a command signal is received
from the operator, keeping the pump 118 at standby or in a mini-stroke mode
for providing pressure. The manifold and valve assembly 126 is further
20 coupled to an accumulator 142 as well as to a boom winch assembly 136 and
a load, or hook, winch assembly 130 for controlling the up and down operation
of the boom and hook. The manifold and valve assembly 126 further limits
pressure to the accumulator 142 and a pilot control system 134. The
accumulator 142 functions as a short term, standby pressure source and
CA 02286949 1999-10-18
19
serves to maintain a more constant pressure for the pilot control system. The
hook winch assembly 130 reduces brake release pressure, allows for brake
release only when the hook control is in the down position, and includes a
counter balance valve to control hook down loads. The boom winch assembly
136 controls the raising and lowering of the boom.
A manifold assembly 132 receives inputs from the hook and boom winch
assemblies 130,136. The higher pressure from one of these two assemblies is
selected and is provided to a load sense connection in the power beyond
cover 124 coupled to the valve assembly 122. The pilot control system 134
~ o includes various operator controls such as a bulldozerlpipelayer mode
control
valve 134a which is connected to lockout cylinders 138a and 138b for locking
the track roller frames in fixed position on the main frame as previously
described. When in the bulldozer mode of operation, the mode control valve
134a deprives first and second remote hydraulic control switches 134b and
i s 134c of oil so that the valve spools of the manifold and valve assembly
126
cannot shift so as to lock the hook and boom winches by means of the
respective winch brakes. The bulldozerlpipelayer mode control valve 134a
also unlocks the hook and boom winch assemblies 130,136 for permitting
pipelayer operation when in the pipelayer mode. Operator controls 134 further
20 include first and second remote hydraulic control switches 134b and 134c.
The first remote control switch 134b shifts a pilot operated valve section
(not
shown) to raise or lower the boom. The second remote control switch 134c
shifts the pilot operated valve section to raise or lower the hook and to also
activate the winch quick drop valve. A boom stop valve 140 is coupled to the
CA 02286949 1999-10-18
manifold and valve assembly 126 for limiting upward displacement of the
boom and preventing over rotation of the boom.
Referring to FIG. 10a, there is shown a simplified block diagram of a
prior art load winch drive train 160 such as used in a conventional pipelayer.
5 The load winch drive train 160 includes a cable drum 162 coupled to a free
fall
clutch 164 which, in turn, is connected to winch gears including secondary
winch gears 166 and primary winch gears 168. The primary winch gears 168
are connected to a winch drive motor 172 by means of a brake 170. In the
prior art load winch drive train 160, a free fall feature is incorporated to
~ o disengage a load in the case of a dangerous or emergency situation such as
when the stability of the pipelayer is lost. This would typically occur when
lifting a heavy load and either the position of the boom or the orientation of
the
pipelayer apparatus presents an unstable situation. When an unstable
situation is detected, the clutch 164 in the prior art load winch drive train
160
i 5 disconnects the cable drum 162 from the entire drive train including the
secondary and primary winch gears 166, 168 as well as from the brake 170
and drive motor 172.
Referring to FIG. 10b, there is shown a simplified block diagram of a
load winch drive train 178 incorporated in a pipelayer in accordance with the
20 present invention. The inventive load winch drive train 178 includes a
cable
drum 180 connected to a quick drop clutch 184 via secondary winch gears
182. The clutch 184 is, in turn, connected to the drive motor 190 via the
combination of primary winch gears 186 and a brake 188. In the event an
unstable condition of the pipelayer is sensed, the clutch 184 does not
CA 02286949 1999-10-18
21
disconnect the secondary winch gears 182 from the cable drum 180, but rather
only disconnects the primary winch gears 186, the brake 188 and the motor
190 from the secondary winch gears in allowing the load to fall under its own
weight. By disengaging only the primary winch gears 186 rather than the
combination of the primary winch gears and the secondary winch gears 182
from the cable drum 180, the quick drop clutch 184 in the inventive load winch
drive train 178 provides a simpler, less expensive arrangement for enabling
the quick drop release of a suspended load. The release of a suspended load
by the inventive load winch drive train 178 is accomplished by disconnecting
i o the cable drum 180 from only a portion of the drive train rather than from
the
entire drive train allowing the suspended load to drop as described in detail
in
the following paragraph.
Referring to FIG. 11, there is shown a longitudinal sectional view of the
inventive load winch drive train 178 which is shown in FIG. 10b in simplified
i s block diagram form. When the quick drop mode of operation is actuated,
hydraulic fluid, or oil, enters the clutch 184 via an oil inlet adapter 206.
The oil
causes a piston 194 in the quick drop clutch 184 to move to the right as
viewed
in FIG. 11. Rightward movement of piston 194 causes the piston to press
against a series of springs 192 resulting in release of the multi-disc clutch
184.
2Q More specifically, rightward displacement of the piston 194 allows a hub
202, a
connecting shaft 198, and an internal gear 196 to turn freely as a unit. With
the internal gear 196 turning freely, no effective torque is transmitted
through
primary planet gears 210 to a primary sungear 208. No effective torque is also
transmitted through the primary sungear 208 to a primary planet hub 212. The
CA 02286949 1999-10-18
22
primary planet hub 212 is splined to a sungear 214 by means of a rotor clip
216. Thus, when the clutch 184 is released, the final planet assembly rotates
with the cable drum 180 around the stationary sungear 214. By disengaging
the clutch 184, the cable drum 180 and the secondary winch gears 182 are
s uncoupled from the primary drive gears 186 (which include the planetary gear
210, the internal gear 196, and sungear 208), the motor 190, and the winch
brake 188. With the clutch 184 disengaged, a load suspended from a cable
(not shown) wrapped around the cable drum 180 will drop under its own
weight.
i o There has thus been shown a combination bulldozer and pipelayer
having a front mounted earth moving attachment such as a blade or bucket
and a side mounted pipelayer attachment for lifting and positioning sections
of
pipe. A pair of endless track roller frames are mounted to respective sides of
the vehicle's main frame and are free to oscillate up and down about a
15 horizontal axis passing through the main frame when operated as a bulldozer
for improved traction and grading characteristics. The vertically oscillating
track roller frames transmit ground impact loads directly to the main frame
and
provide a more comfortable ride for the operator when in the bulldozing mode
of operation. In the pipelayer mode of operation, the track roller frames are
20 locked in fixed position on the main frame and prevented from oscillating
to
provide a stable platform for lifting and transporting heavy loads such as
sections of pipe. The side mounted pipelayer attachment includes a multi-
section folding boom which can be stowed in a retracted position in closely
spaced relation to a side and the top of the vehicle and can also be extended
CA 02286949 1999-10-18
23
to the use position for lifting heavy loads using the pipelayer winch controls
with minimal manual effort. When the boom is retracted in closely spaced
relation to the vehicle, the vehicle may be operated in narrow, low spaces as
a
bulldozer without removing the boom. The close fitting relation of the folded
s boom to the vehicle also reduces the likelihood of impact damage to the boom
when the vehicle is operated in the bulldozer mode and also during shipping.
The vehicle's hydraulic system is connected in series to the pipelayer's
series
hydraulic system to permit operation of the pipelayer boom and load winches
at the same speed for improved load control without stalling the heavier
loaded
i o winch drum.
While particular embodiments of the present invention have been shown
and described, it will be obvious to those skilled in the art that changes and
modifications may be made without departing from the invention in its broader
aspects. Therefore, the aim in the appended claims is to cover all such
changes and modifications as fall within the true spirit and scope of the
invention. The matter set forth in the foregoing description and accompanying
drawings is offered by way of illustration only and not as a limitation. The
actual scope of the invention is intended to be defined in the following
claims
when viewed in their proper perspective based on the prior art.
