Note: Descriptions are shown in the official language in which they were submitted.
SWEEPER WITH HYDRAULIC~LI,Y DRIVEN COMPONENT5
... _ . . .. . _
Field of -the Invention
. _ _
The present invention relates to street sweepers or
the like and more particularly relates to such sweepers
with hydraulically driven and controlled components and a
hydraulic vehicle propulsion system.
Description of the Prior Art
Street sweepers with mechanical drives to the vehicle
propulsion wheels and to the sweeper components are well
known in the art as evidenced by United States Patent
3,310,825 which issued to Tamny on March 28, 1967.
Street sweepers with mechanical drives to the
propulsion wheels and hydraulic drives to certain sweeper
components are illustrated in United States Patent
3,316,578 to Tamny dated May 2, 1967; and Woodworth Patent
3,636,580 which issued on January 25, 1982.
Summary of the Invention
According to an aspect of the invention, a mobile
sweeper having a chassis supporting debris hopper means
having a hopper body defined by walls including a top wall
having a pivotal door means therein and a rear wall; said
hopper means supported for pivotal movement about a
horizontal axis disposed at a fixed distance above the
chassis and near the rear end of the sweeper for movement
between a debris retaining position with the door means
closed in i-ts debris retaining position, and a debris
dumping position with the door means open and with the
rear wall of the hopper angled downwardly and rearwardly,
said hopper means and said door means each defining
sequentially actuated debris control means, the
combination comprises:
a power driven control pump;
a hydraulic fluid -tank in flow communication with
said pump for providing fluid to said pump and said
components;
means defining at least one first hydraulic cylinder
connected between said chassis and said hopper means for
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plvoting said hopper means between the debris retaining
position and the debris releasing position,
means defining a second hydraulic cylinder for
pivoting said door means between its normally closed
debris retaining position and an open debris releasiny
position;
conduit means interconnecting said first and second
hydraulic cylinders to said pump;
valving means in said conduit means for receiving
fluid from said pump for first diverting Eluid into one of
said hydraulic cylinder means for pivoting the associated
debris control means between its debris retaining position
and a debris releasing position, in response to said at
- least one hydraulic cylinder means reaching the debris
releasing position, said valving means immediately
diverting fluid into the other of said hydraulic cylinders
for pivoting the other debris controlling means between
its debris retaining position and its debris releasing
position for releasing the debris from the hopper means;
said valving means ircluding a directional valve
movable between a neutral fluid blocking position and a
position permitting fluid to flow therepast, said
directional valve being connected to first and second
branches of said conduit means between said pump and said
at least one hydraulic cylinder; and
a pilot operated check valve in each of said first
and second branches and operated by pilot pressure in the
opposite one of said first and second branches for
hydraulically locking said first and second hydraulic
30 cylinders in position when said directional valve is in
said neutral position.
Brief Description of the Drawings
Figure 1 is a diagrammatic perspective with parts in
phantom and other parts broken away illustrating a mobile
street sweeper which incorporates the hydraulic components
of the present invention.
Figure 2 is a hydraulic diagram of the pilot
controlled hydraulic traction drive system of the mobile
street sweeper of Figure 1.
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2a
Figure 3 is a hydraulic control and auxi]iary drive
of the street sweeper of Figure 1.
Figure ~ illustrates a pick up broom pressure gauge
located in the vehicle cab for indicating the pick up
broom sweeping pressure.
Figure 5 illustrates one of the gutter broom pressure
gauges located in the cab for indicating the gutter broom
sweeping pressure.
Figure 6 ls a diagrammatic illustration of one of the
swash plate propulsion drive motors.
Figure 7 is a diagrammatic illustration of an
alternate mechanical, swash plate control system.
Figure 7A is a hydraulic diagram of the
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mechanically operated valve and its connections into the
circuit of Figure 2.
DESCRIPTION OF l'HE PREFERRED EM~ODIMENT
The remote controlled hydrostatic traction drive
system 10 (Fig. 2) and the hydraulic control and auxiliary
drive system 12 (Fig. 3~ are designed to control and
operate the several components of the street sweeper
illustrated in Figure 1.
The street sweeper 14 includes a chassis 16
supported on a pair of rear wheels 18, 20 driven by
hydraulic motors 22,24, respectively. A single steerable
front wheel 26 is journaled on a yoke 28 which pivotally
supports the front of the chassis 16 and is steered by a
hydraulic cylinder 30 connected between the chassis 16 and
the yoXe 28.
A debris pick-up broom 32 is rotably mounted on a
pair of pivot arms 34,36 having their upper ends pivotally
supported by the chassis 16 for movement about a
horizontal pivot axis 3~. The pick-up broom 32 is driven
by a hydraulic motor 40 and is moved between an elevated
transport position and a lowered sweeping position by a
hydraulic cylinder 44~ The hydraulic cylinder 44 has one
end anchored to the chassis 16 and h~s its other end
connected to one end of a resilient connector 46. Cables
48,49 are attached to the other end of the associated
resilient connector 46 and to the free end of the
associated pivot arms 34 or 36 respectively after being
trained around cable direction controlling sheaves 50 and
52 journaled to the chassis 16 as clearly illustrated in
Figure 1. As will be described hereinafter, a pressure
gauge 54 (Fig~ 4) communicates with the pick-up broom
cylinder 44 for equalizing the pressure in each cylinder
to assure that the pick-up broom will wear evenly, i.e.,
does not wear into a frusto-conical shape. Also~ the
pressure gauge 54 is calibrated to provide different
surface engaging pressures depending upon the amount of
sweeping force required to clean the road or other surface
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being swept.
The sweeper 14 also includes left and right
gutter brooms 60,62 driven by hydraulic motors 64,66
mounted on support arms 68,70 which are in turn mounted on
the chassis 16 for generally vertical movement and
generally horizontal pivotal movement by means not fully
shown. Cables 72 and 74 are connected between the chassis
15 and the associated arms 68,70 to control the transverse
movement of the gutter brooms 60,62. The gutter brooms
60,62 are each moved between a raised transport position
and a lowered road engaging gutter sweeping position by
hydraulic cylinders 76,7~. One end of each hydraulic
cylinder 76,78 is connected to the chassis 16, and the
other end is connected to the associated support arms
68,70 by cables 80, 82 trained over sheaves 84,86 and
conventional resilient connectors 88,90. Pressure gauges
92,94 (Figs. 3 and 5) are connected to the hydraulic
cylinders 76,78, respectively, and are observed by an
operator for indicating the sweeping pressure applied by
the associated gutter broom against the road being
cleaned. When the gutter brooms 60,62 are raised to the
transport positions, the cables 72,74 pull the brooms
inwardly toward the centerline of the chassis.
The debris accumulated by the pick-up broom 32
and the gutter brooms 6V,62 is swept into the housing 100
of an elevator 102. The elevator includes a plurality of
paddle wheels 104 (three being illustrated in Figure 1)
each independently driven by a hydraulic motor 106 for
progressively elevating the debris and discharging it into
a hopper 108. A low volume air blower 110 driven by a
hydraulic motor 112 is mounted on the hopper for creating
an updraft of air through the elevator 102 thereby aiding
the movement of leaves or the like into the hopper 108.
The hopper 10~ is supported by the chassis 16 for
pivotal movement about an axis 113 between the illustrated
debris receiving position and a debris dumping position.
A pair of hydraulic cylinders 114,116 are pivotally
--5--
connected ~etween the chassis 16 and the hopper 108 to
pivot the hopper between the two positions. The hopper
108 includes a gate 118 which is pivoted to the hopper
body 120. A gate opening hydraulic cylinder 122 is
5 connected between the body 120 and the gate 118 for
pivoting the qate between an open position and the
illustrated closed position.
An operator's cab 126 (shown in phantom lines in
Figure 1) is mounted on the front of th chassis 16 and
includes the ssveral hydraulic controls, generally
designated 128, as well as the usual sweeper controls (not
shown) fox operating the vehicle. The sweeper also
includes an engine 130 which drives several hydraulic
pumps at 132 and which are mounted on the chassis 16 near
the rear end thereof.
Prior to describing the remote control
hydrostatic drive system 10, it is ~elt that a brief
description of the construction of the prior art
hydrostatic motors 22 and 24 would be helpful in
understanding the invention.
Figure 6 diagrammatically illustrates motor 22
which is identical to the motor 24 and includes a
non-rotatable swash plate 134 journaled on a rotatable
motor shaft 135 and illustrated in its starting position.
25 Main pistons 136 and cylinders 137 and secured to and
rotate with the shaft 135 in response to receiving high
pressure fluid in one cylinder and discharging the fluid
from the other cylinder. The pistons include feet 138
which slide against the non-rotatable swash plate thus
imparting rotation to the shaft and the main piston and
cylinder units slidably connected thereto. A "forward"
non-rotatable control piston 139 and cylinder 140, and a
"reverse" control piston 141 and cylinder 142 are provided
for controlling the angle of the swash plate 134 and thus
35 the speed of the motors. The pistons 139,141 are
connected to the swash place 134. Stationary abutments
144 and 146 limit the pivotal movement of the swash place
between a maximum displacement, low speed 18 position and
a minimum displacement high speed 8 position.
If a more complete description of the several
sweeper components mentioned above is desired, reference
may be had to the appropriate ones of the above cross
referenced applications.
Remote Control Hydrostatic Traction Drive
The remote control hydrostatic traction drive
system 10 (Fig. 2) comprises a pump assembly 150 which
includes the components located within a housing
illustrated by phantom lines 152; left and right motor
assemblies 154,156 that include the components located
within the housings illustrated by phantom lines 158,160,
respectively; a valve assembly 162 illustrated between the
motor assemblies and outlined within phantom lines 164: a
two-speed shift control assembly 168 illustrated within
phantom lines 170; an accelerator pedal control assembly
172 illustrated within phantom lines 174; and a
conventional sump or tank T.
The pump assembly 150 includes a main positive
displacement, swash plate pump 180 and an auxiliary pump
182 both of which are of conventional design and are
driven by the vehicle engine 130 (Fig. 1) in a
counterclockwise direction identified by the arrow CW
(Fig. 2). The auxiliary pump 182 draws hydraulic fluid
through conduit 183 from the tank T and circulates the
fluid into the main pump 180 to first charge and
thereafter maintain the main pump charged. The auxiliary
pump 182 also circulates the fluid through a conventional
cooler C and provides make-up fluid for the main pump 180.
The left hydraulic wheel motor 22 (Figs. 1 and 2)
and the right hydraulic wheel motor 2~ are conventional
positive ~isplacement, swash p~ate motors which receive
hydraulic wheel driving fluid from the main pump 180 and
receive control fluid from the auxiliary pump. As is well
known in the art, when the pump 180 is being started the
swash plate will be positioned substantially normal to its
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axis of rotation and thus the pistons of the pump will be
at low displacement and will pump very little, if any,
fluid. ~onversely, the swash plate of each motor 22,24
will be positioned at the maximum angle relative to its
axis of rotation, thus the pistons of the motors 22,24
will be at maximum displacement at start up.
With main pump 180 and auxiliary pump 182
started, hydraulic fluid will be drawn by the auxiliary
pump 182 from the tank T through a suction conduit 1~3
which directs fluid into conduits 18~ and 1~6. When the
pressure operated relief valve 188 is opened against the
urging of a Rpring 190 thereby directing fluid into pilot
lines 192 and 194. The pressure in line 192 is directed
through a remote control pilot operated four-way valve 200
in the pump assembly 150 when in its illustrated neutral
position. Fluid at equal pressure is thus directed
through pilot lines 202 and 204 to the forward swash plate
control unit 206 and to the reverse swash plate control
unit 208 of the main hydraulic pump 180 thus maintaining
the main pump at cr near zero displacement.
When accelerator pedal forward control valve 210
and reverse valve 212, of the accelerated pedal control
assembly 172, are in neutral as indicated in Figure 2,
pressure in auxiliary pump line 186 is directed into
conduit 214 and is blocked from further flow by the valves
210 and 212. Fluid in pilot line 216 flows through a
parallel passage in a pressure override valve 218 but is
blocked from further flow by the centered core of remote
control valve 200.
Auxiliary pump fluid in line 194 enters conduits
219,220 and flows at equal pressure through valves 210 and
212 through conduit 222 and 224, respectively, thereby
applying equal pressure on opposite ends of valve 200 thus
maintaining the valve in the illustrated centered position.
It will be noted that fluid in line 194 normally
flows through cooler C to tank T. However, a solenoid
operated cooler by-pass valve 225 may be opened by an
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operator actuated electric switch 222 located in the
sweeper's cab to by-pass the cooler C for cold starts or
the like.
With the a~celerator pedal in the illustrated
neutral position, pilot pressure from conduit 192 is
directed to the motor assemblies 154,156 through pilot
line 226. Pilot pressure and make-up fluid from line 226
enters the right propulsion motor 24 through line 228; and
enters the left propulsion motor 22 through lines 230 and
232.
When the operator wishes to drive the sweeper in
a forward direction, the forward accelerator pedal is
depressed to open variable capacity forward valve 210 the
desired amount. Fluid from auxiliary pump 182 and line
186 then flows through forward valve 210 into pilot line
222 which shifts the spool of the remote control valve 200
upwardly (Fig. 2) to the parallel passage position. Pilot
fluid from line 216 then flows through the parallel
passages in valves 218 and 200, and line 202 to the
forward swash place displacement control unit 206 thus
pumping propulsion fluid at the desired ~apacity through a
forward conduit 242 into the two hydraulic motors 22 and
24 to drive the motors in a forward direction. Low
pressure fluid discharged from the motors 22 and 24 return
through "reverse" conduits 244 to the reverse outlet of
the variable displacement pump 180.
In order to drive the sweeper in reverse, the
operator releases the forward valve 210 and depresses the
reverse valve 212. Fluid then flows from the line 186,
through reverse valve 212, through line 224 into the top
(as illustrated in Figure 2) of the valve 200 thereby
shifting the valve 200 to its cross-passage position.
Pilot fluid from line 216 then flows into conduit 204 to
the reverse swash plate control unit 20~ which then pumps
propulsion fluid into the reverse ports of the two motors
22 and 24 through "reverse" conduits 244 thereby driving
the vehicle in reverse direction with the return fluid
_g_
returning to the pump 180 through "forward" conduit 242.
The valve assembly 162 receives hydraulic fluid
from forward conduit 242 and reverse conduit 244 which
directs fluid into conduits 246 and 248, respectively.
Conduits 246 and 248 co~municate with 6000 psi spring
loaded pressure relief valves 250 and 252, respectively.
The conduits 246 and 248 also communicate with opposite
ends of the three-position pilot operated shuttle valve
254. When driving the vehicle in a forward direction,
high pressure will be present in "forward" conduits 242
and 246, and the conduits 244 and 248 will be at a lower
pressure thus shifting the core of shuttle valve 254
downwardly (Fig. 2).
The components in the valve assembly 162
cooperate with the components in the two-speed shift
control assembly 168 in order to control the displacement
of the pistons 136 (Fig. 6) in the motors 22,24 and thus
the output speed of the motors.
When the motors 22,24 are being driven forward in
response to opening accelerator pedal valve 210, the
shuttle valve 254 is piloted down (Fig. 2) with its cross
passage F communicating with low pressure line 248 and
with a line 256 connected to a 165 psi relief valve 258.
When the pressure in line 256 is less than 165 psi, valve
258 remains closed and prevents flow of fluid through
motor cylinders 136 (Fig. 6).
When relief valve 258 is opened by a pressure is
excess of 165 psi, fluid flows through passage F of
shuttle valve 254 and through conduit 256 to the shift
control assembly 168. This fluid then flows through
conduit 259 and is blocked by closed solenoid valve 260.
This fluid further flows through conduit 262, a
cross-passage in pilot operated valve 264, through conduit
266 and into cylinder 140 (Fig. 6) of forward swash plate
35 control unit 268 of each motor 22,24 thus urging the swash
plate 134 toward the low speed 18 position. Some fluid
drains out of cylinder 142 of reverse swash plate control
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units 270 of each motor for return to the two-speed shift
assembly 168 through conduits 272 and 273. ThiS return
fluid then ~lows through a cross-passage in valve 264, and
returns to the reverse control unit 208 of the pump 180
through conduits 274,230,226,192 a parallel passage in
valve 200 and conduit 194. It will be noted that excess
fluid in line 256 will pass through the open relief valve
258 and flow into line 230 for return to the reverse
control unit 208 as above described. The hydraulic motors
22,24 will drive the sweeper at a low speed range of about
0-10 miles per hour when receiving fluid through the last
described circuits.
The solenoid valve 260 of the two-speed shift
assembly 168 is opened in response to the operator closing
a switch 276 in the cab when a speed range of between
about 0-20 miles per hour in the forward direction is
desired. High pressure fluid then flows from conduits 256
and 259, through open solenoid valve 260, and through
conduit 278 which pilots valve 264 to its parallel passage
position. Some of the high pressure fluid then flows
through a restricter 279 into return line 274, while the
bulk of the fluid flows from conduit 262 through a
parallel passage in valve 264, through previously
described conduits to control cylinder 142 (Fig. 6) in
25 each swash plate control unit 268 of motors 22,24 thus
urging the swash plate 134towards its high speed 8
position. Some fluid returns from the cylinder 140 of the
forward swash plate control units 268 of each motor 22,24,
and flows through previously described conduits and the
other parallel passage in valve 264 for return to conduit
274 and the tank T through previously described low speed
circuits.
It will be understood that springs are provided
in each motor for urging the swash plate toward their low
speed, maximum displacement 18 relative to a plane
perpendicular to the shaft of the motor; and that maximum
speed, minimum piston displacement occurs at about 8 from
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said plane.
When driving the vehicle in reverse, the operator
actuates the accelerator pedal control to reverse the
direction of flow of fluid into the main pump 180 as
previously described thereby directing high pressure fluid
through conauit 244 into th reverse conduits 248 of the
motor assembly 162 which pilots shuttle valve 25~ upwardly
causing fluid from conduit 246 to flow through passage R
in shuttle valve 254 thereby driving the motors 22,24 in
their reverse direction. Since the operations performed
by the valve assembly 162 and the two-speed shi f t control
assembly 168 are substantially the same as that described
in regard to controlling the forward speed of the sweeper,
the description of this portion of the circuit is
considered unnecessary.
The circuit 10 (Fig. 2~ also includes high
pressure protection components which protect the hydraulic
components from damage. Assuming that the accelerator is
actuated to open the "forward" valve 210, and that
hydraulic pressure in conduits 242 and 246 exceed 6000
psi, relief valve 250 will first open thereby directing
6000 psi fluid through valve 250 into "reverse" conduit
248, thus balancing the pressure on opposite sides of the
two motors 22,24 and returning the shuttle valve to its
illustrated central position thereby stopping the flow of
fluid through the motors. The 6000 psi pressure in
conduit 242 will also be directed into a pilot operated
6000 psi override control valve 286 to shift override
valve 286 to the left (Fig. 2) thereby piloting valve 218
to its cross-passage position. With valve 218 in its
cross-passage position, further flow from line 216 through
the valve 218 is blocked and conduit 202 communicating
with the forward swash plate unit 206 of the main pump 180
is opened through cross passage in valve 218 to reverse
line 192 thereby reducing the pressure in line 202. Thus,
the pressure is reduced below 6000 psi in the hydraulic
system 10 of Figure 2 allowing the protective components
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to return to their illustrated positions.
If the vehicle is being driven in a reverse
direction the pressure in conduit 248 exceeds 6000 psi,
relief valve 252 will first open, rather than or before
relief valve 250 opens, thus opening the pressure override
control valve 286 and the pilot operated valve 218 to
reverse the flow of ~luid to the control units 208,206 of
the main pump 180 until the maximum pressure drops to a
safe pressure below 6000 psi.
Figures 7 and 7A diagrammatically illustrate an
alternate, mechanical swash plate control system 290 for
the main pump 180 which would replace the remote control
valves 200,208 and 218 ~Fig. 2) as well as the pedal
operated valves 210 and 212 and associated conduits. The
single valve 200a (Fig. 7A) would replace the several
omitted valves and would be connected to the lines
186,192, 202 and 204 as indicated. The parallel passage
position of valve 200a is the "forward" position and the
cross passage position is the "reverse" position.
The mechanical swash plate system 290 (Fig. 7)
has a pedal 291 in the operator's cab 126 with a forward
(FWD) toe portion and a reverse (REV) heel portion. The
pedal 291 is secured to a rocker arm 292 that is pivoted
to the vehicle about axis 293. A sheathed cable 294
connects the other end of the rocker arm 292 to a swash
plate adjusting lever 294 of a conventional positive
displacement swash plate pump 180a. The pump may be of a
type manufactured by Eaton Corporation, Spencer, Iowa, and
only the manual pump control valve thereof is shown. As
illustrated, the pump is in its zero displacement
position. The operator pivots the pedal 291 with his toe
to move the valve 200a to its parallel passage position to
drive the pump and vehicle forward, and pivots the pedal
with his heel to drive the pump and vehicle in reverse.
It will be apparent that the specific fluid
pressures referred to herein, and the pressures to be
referred to in regard to the circuit of Figure 3, are
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given as approximately pressures to ~e used with the
preferred embodiment of the sweeper of the present
invention.
Hydraulic Control and Auxiliar~ Drive System
The hydraulic control and auxiliary drive system
12 (Fig. 3) includes a fixed displacement auxiliary drive
pump 300 driven by the engine 130 (Fig. 1) which receives
fluid from a sump or tank T' and returns the fluid to the
tank t' through one of a plurality of circuits. The fluid
may return through conduit 302, a cross passage in
mechanically operated pick-up broom valve 304, a conduit
305 having a heat exchanger therein (not shown) and then
to tank T' provided the valve 304 is in its bypass
position as illustrated in Figure 3.
When the pick-up broom 32, the left gutter broo~
69 and the right gutter broom 62 are in their raised
transport positions; the pick-up broom valve 304, the left
gutter broom, valve 306 and the right gutter broom valve
308 are all in their illustrated bypass positions-
20 Preferably the valves 304,306 and 308 are mounted in the
cab 126 and are manually operated by the operator.
However, it is within the scope of the invention to mount
these valves in position to be shifted to their parallel
passage position in response to lowering the pick-up boom
32, the left gutter broom 60 and the right gutter broom
62, respectively.
In response to shifting the valve 304 to its
parallel passage position the flow therethrough is
blocked. Fluid from the pump 300 then flows through a
parallel passage in pilot operated valve 310 and through
said plurality of elevator motors 106 (only one being
shown in Figure 3) to drive the motors 106 in their
forward or debris elevating direction. If both of the
gutter brooms 60,62 are in their raised transport
position, fluid returns to tank T' through the illustrated
cross passages in the valves 306,308 and conduit 305. If
valve 306 is shifted to the parallel passage position thus
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blocking flow there~hrough, fluid will flow through the
motor 64 and thereby driving the left gutter broom in its
s~eeping direction. Similarly, when the valve 308 closes
thereby forcing the fluid through the motor 66 of the
right gutter broom 62 the broom 62 will be driven in its
sweeping direction. If the discharge pressure of the pump
300 should exceed 4300 psi, pilot pressure from conduits
312 and 314 opens pressure relief valve 316 to discharge
fluid to the tank T' through conduits 318 and 305.
A control pump 330 is also driven by the engine
130 (Fig. 1) and draws fluid from the tank T' through the
lower portions of conduits 305,318 and 332. The pump 330
is a priority flow pump with two outlets 334 and 336. A
manually operated valve 337 must be shifted from the
illustrated by-pass position to is closed position to
operate pump 330. If pressure from the control pump
outlet 334 should exceed 2500 psi after passing through a
flow restricter or orifice 338, a pressure relief valve
340 is opened thereby returning fluid to the inlet conduit
of the pump 330.
High pressure fluid flows from pump outlet 336
through conduits 342 and 344 to a plurality of components,
while low pressure fluid discharges from the several
components and returns to tank T' through conduits
346,348,350 and 305.
When it is desired to pivo-t the hopper 108 (Fig.
1), open the hopper door 118; and/or change the elevation
of the pick-up broom 32 or gutter brooms 60,62; the
operator must first close the switch 352 (Fig. 3) to shift
a solenoid valve 354 from the illustrated by-pass position
to a position closing pilot line 356 having an orifice
356' therein closing spring loaded, pilot operated
pressure relief valve 358 preventing flow of fluid through
conduit 360 directly to tank T'.
When it is desired to dump the hopper 108, a
switch 362 is closed thereby shifting solenoid valve 364
to its open position allowing high pressure fluid to flow
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through pilot line 366 having an orifice 366' therein
thereby shifting four-way valve 368 ~o its parallel
passage position. High pressure fluid is then directed
through conduits 370 and 372 into the closed end of the
cylinders 114,116 (only one being shown) ~hereby extending
the pistons and pivoting the hopper into its dumping
position. It will be noted that pilot pressure from
conduit 372 unseats check valve 374 in conduit 376 to
permit fluid to discharge from the rod ends of the
10 cylinders 114,116 and pass through a parallel passage in
the valve 368 and through conduit 378 into return conduit
346.
After the cylinders 114,116 have been fully
extended, hydraulic pressure increases in line 372 to a
pressure in excess of 2000 psi thereby causing pilot
pressure in line 3B0 to open pressure relief valve 382
allowing hydraulic fluid to flow through conduits 384 into
hopper door cylinder 122 extending the same and thus
opening hopper door 118 (Fig. 1).
When the hopper is empty and the door and hopper
are to be returned to their debris receiving positions,
switch 362 is opened and a switch 386 is closed thus
opening solenoid valve 388 allowing high pressure fluid to
flow through a pilot line 3gO with an orifice therein
thereby piloting valve 368 into its cross-passage
position. High pressure fluid then flows from line 370
through a cross-passage in valve 368, through check valve
374 and conduit 376 and into the rod end of cylinder
114,116 and 122. Check valve 392 in line 372 is opened by
pilot pressure from conduit 376. The fluid discharged
from cylinders 114,116 for flow past check valve 392 in
conduit 372, and through a cross passage in valve 368 for
return to tank T through previously described conduits.
When the hopper and door return to their debris receiving
positions, the operator opens switch 386 thereby returning
valve 368 to its neutral 374,392 hydraulically lock the
cylinders 114,116 and 122 in fixed position after valve
. ~2~7~
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368 returns to its illustrated centered position.
The pick-up broom cylinder 44 is illustrated in
retracted position thus holding the broom 32 in its raised
transport position~ Since the hydraulic components
associated with the pick-up broom cylinder 44 are similar
to those of the hydraulic hopper components, only the
major portions will be described. In order to lower the
pick-up broom 32, the operator closes a switch 400 thereby
shifting solenoid valve 402 to its parallel passage
position which pilots four-way ~alve 404 into its parallel
passage position. Fluid from high pressure conduit 344
flows through conduit 405, through parallel passages in
valve 404, past pilot operated check valve 406 to extend
the piston in the cylinder 44. Fluid in the rod end of
the cylinder 44 flow past pilot opened check valve 408,
through a parallel passage in four-way valve 404 and
returns to tank T' through conduit 410 and the previously
described return conduits.
In order to raise the pick-up broom 32, the
switch 400 is opened and a switch 412 is closed thus
opening solenoid valve 414 which pilots four-way valve 404
to its cross-passage position. Fluid then flows past
check valve 408 into the rod end of cylinder 44 thereby
retracting the rod and returning fluid to tank T' through
the pilot opened check valve 406, the four-way valve 404,
conduit 410 and the previously described return conduits.
A pick-up broom pressure gauge 54 (Figs. 3 and 4)
communicates with the closed e~d of pick-up broom cylinder
44 and is mounted in the cab for view by the operator
thereby enabling the operator to determine the minimum
broom pressure against the road being cleaned to provide
adequate sweeping and thus minimizing broom wear. As
~hown in Figure 4, the pick-up broom pressure gauge 54 is
calibrated in accordance with the approximate pick-up
broom pressures against the surface as follows: heavy
0~45 psi; medium 45-80 psi; light 80-100 psi. The broom
is lifted with pressures between 100-300 psi and varies
.L7
due to broom wear or the like; and a locking transport
position between 300-600 psi.
It will be appreciated that only one gutter will
be swept at a time, and accordingly, separate circuits are
provided for the left gutter broom 60 and the right gutter
broom 62.
In order to lower the left guttPr broom 60~
switch 420 is closed by the operator thereby opening
solenoid valve 422 and piloting four-way valve 424 into
its parallel passage position which directs fluid into the
closed end of cylinder 78 past check valve 426. Fluid is
discharged from the rod end of the cylinder 78 through
pilot opened check valve 428, four-way valve 424, and
conduit 430 for return to tank T'. The left ~utter broom
78 is raised by opening switch 420 and closing switch 432
which opens solenoid valve 434. Fluid flows through valve
434 and pilots four-way valve 424 into its cross passage
position thereby directing fluid past check valve 428 to
retract the piston rod of cylinder 78. Fluid is then
discharged from the closed end of cylinder 78 past pilot
opened check valve 426, through a cross passage in
four-way valve 424 and to tank T' through conduit 430. A
left gutter broom pressure gauge 94 (Figs. 3 and 5) is
located in the operator's cab and is connected to the
closed end of the cylinder 78.
Similarly, the riyht gutter broom 62 is lowered
by closing switch 440 which opens solenoid valve 442
thereby piloting four-way valve 44 to its parrallel
passage position directing fluid past check valve 446 into
the closed end of right gutter broom cylinder 76. Fluid
in the rod end of cylinder 76 is discharged past check
valve 448 through a parallel passage in four-way valve 444
and to tank T' through conduit 450. The right gutter
broom 62 is raised after the toggle switch 440 is opened
and switch 452 is closed thereby opening solenoid valve
454 which pilots four-way valve 444 to its cross passage
position. Fluid then flows past check valve 448 into the
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rod end of cylinder 76 causing fluid in the closed end of
cylinder 76 to flow to sump past pilot opened check valve
446, a cross passage in four-way valve 444 and through
conduits 450, 346, 348, 350 and 305.
The right gutter broom pressure gauge 92 is
located in the operator's cab and is connected to the
closed end of the cylinder 76 to indicate the pressure
therein. It will be understood that the left gutter broom
pressure gauge 94 and the right gutter broom gauge 92 are
identically calibrated to indicate the gutter broom
pressure against the surface being cleaned. As shown in
Figure 5, the pressure gauges 92,94 have approximate
gutter broom sweeping pressure as follows: heavy 85-110
psi; medium 110-133 psi; light 133-156 psi. The gutter
broom is lifted to its transport position between
approximately 156-300 psi, and the broom is hydraulically
locked in transport position at about 600 psi.
As previously described and as illustrated in
Figure 3, the pump 300 directs fluid through parallel
passages in pilot operated valve 310 to drive the elevator
motors 106 in a forward or debris elevating direction. In
order to reverse the direction of the elevator paddle
wheel 104 (Fig. 1) and motors 106 (only one being shown in
Figure 3), a solenoid valve 460 is connected by pilot
25 lines 462, 464 to a high pressure conduit 342 and low
pressure tank return conduit 350 of pump 330. A pilot
line 466 connects the solenoid valve 460 to the upper
pilot (Fig. 3) of valve 310. ~he operator closes switch
468 in the operator's cab which energizes solenoid valve
30 460 to direct high pressure fluid from pilot line 462
thereby shifting four-way pilot valve 310 to its cross
passage position. In this way, the direction of a
movement of the elevator motors 106 and paddle wheels 104
are reversed to clear debris therefrom.
Although manually operated switch control
solenoid valve 460 and pilot operated valve 310 are
illustrated for controlling the direction in which the
'7~
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elevator motor is driven, it will be understood that these
valves may be replaced by a single manually operated valve
similar to valve 310 but mounted in the cab without
electrical or pilot inputs.
High pressure fluid from priority flow pump 330
out of port 334 flows through orifice 338 and a restricted
conduit 472 to a steering wheel controlled Hydraulic
steering valve 474 which operates a well known hydraulic
assist steering motor 476 and the hydrau'ic steering
cylinder 30 (Figs. 1 and 3). In order to extend the
piston of the cylinder 30 to make a right turn, the core
of the valve 474 is shifted to the right (Fi~. 3~ thereby
directing high pressure fluid through power assist motor
476 and into the closed end of the steering cylinder 30 to
extend the piston thereof. The fluid in the rod end is
discharged through conduit 478, a cross-passage in valve
474, conduit 480, an adjustable flow control valve 482 set
at 200 psi, a conduit 483, a normally open adjustable
pressure relief valve 484 which closes with the aid of a
spring if the pressure in pilot line 486 exceeds 1000
psi. When valve 484 is open, the floud flows through
conduit 488, an adjustable flow control valve 490 set at
about 210 psi, and through conduit 305 to tank T'. When
turning to the left, the steering wheel is turned to shift
the core of steering valve to the left ~Fig. 3) thus
reversing the direction of fluid flow through the power
assist motor 476 and cylinder 30.
A hydraulic water spray motor 492, for dust
control or the like, is connected in conduit 493 between
conduits 480 and 488, both of which are normally at
substantially balanced pressure of about 100 psi. A
solenoid operated valve 496 is energized by closing a
switch 498 in the cab which blocks conduit 486 and pilots
pressure control valve 484 to its closed position thus
causing the fluid from line 480 to drive pump 492 and to
return th~ tank T' through conduit 493, flow control valve
490, and conduit 305.
'7~
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~ spring set hydraulically released fail safe
brake operated by cylinder 500 is illustrated in locked
position. In order to release the brake, the manually
operated valve 337 is shifted from the illustrated in
locked position. In order to release the brake, ~he
manually operated valve 337 is shifted from the
illustrated by-pass position by the operator at which time
high pressure fluid from pump 330 flows through conduit
472, through a conduit 504, and into the closed end of the
brake cylinder 500 through conduit 508, one port of a
double port, single ball check valve 509 and through
conduit 510 thereby releasing the brake.
In the event the several power driven pumps
become inoperative because of engine failure or the liXe,
the spring set brake 500 will lock the sweeper from
movement. When it is desired to release the brake 500 so
that the sweeper can be towed or the like, the operator
manually operates an emergency hand pump 512. The hand
pump receives fluid from line 506 which flows into the
pump 512 past check valve 514 during the suction stroke.
During the compression stroke, fluid is blocked by check
valve 514 and is moved past check valve 516 in conduit
518, through another port of the double port check valve
509 and then ~lows through conduit 510 into brake cylinder
500 thereby compressing the cylinder and releasing the
brake. The brake will then be hydraulically locked in its
released position by check valve 516, the ball oE check
valve 509 seated against the right port ~Fig. 3), and a
pilot or manually operated control valve 520. If the
hydraulic problem is corrected and the pump 330 is placed
in operation, the fluid in the brake may be released by
closing the valve 337 and directing pilot pressure through
line 522 thereby opening control valve 520 releasing the
fluid into conduit 506. If the problem to the powered
hydraulic system has not been solved, then the control
valve 520 may be manually opened thus releasing fluid to
line 506.
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From the foregoing description it is apparent
that the hydraulic system of the present invention
provides an easily handled control system for changing the
elevation of the hopper and its gate, and each of the
three brooms; and that these components will be
hydraulically locked in their adjusted positions in
response to the closing of the associated manually
operated valves.
The hydraulic system also includes and auxiliary
pump and a hydraulic system for driving the elevator motor
in either direction, and the pick-up broom, the left
gutter broom, and the pick-up broom, the left gutter
broom, and the right gutter broom in response to lowering
the associated brooms and closing the associated by-pass
valves. A remote controlled hydrostatic drive is also
enclosed which features a two-speed shift control.
In the event a customer should prefer valves
which are operated directly by an operator, as opposed to
valves which are shifted by the closing of an electrical
switch by the operator non-electrical valves may be used
in place of the solenoid valves 354; 364,388 and their
pilot operated valve 390, 402,414 and their pilot operated
valve 404; 422,432 and their pilot operated valve 424; and
442,454 and their pilot operated valve 444.
Although the best mode contemplated for carrying
out the present invention has been herein shown and
described, it will be apparent that modification and
variation may be made without departing from what is
regarded to be the subject matter of the invention.
