CA2047305A1 - Hydraulic system for a work vehicle - Google Patents
Hydraulic system for a work vehicleInfo
- Publication number
- CA2047305A1 CA2047305A1 CA 2047305 CA2047305A CA2047305A1 CA 2047305 A1 CA2047305 A1 CA 2047305A1 CA 2047305 CA2047305 CA 2047305 CA 2047305 A CA2047305 A CA 2047305A CA 2047305 A1 CA2047305 A1 CA 2047305A1
- Authority
- CA
- Canada
- Prior art keywords
- hydraulic fluid
- hydraulic
- reservoir
- case drain
- pump
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000012530 fluid Substances 0.000 claims abstract description 136
- 230000005540 biological transmission Effects 0.000 claims abstract description 30
- 238000006073 displacement reaction Methods 0.000 claims description 6
- 230000029058 respiratory gaseous exchange Effects 0.000 claims description 3
- 230000000712 assembly Effects 0.000 description 4
- 238000000429 assembly Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 3
- 230000001960 triggered effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 2
- 239000011236 particulate material Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000005273 aeration Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/0021—Generation or control of line pressure
- F16H61/0025—Supply of control fluid; Pumps therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K23/00—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for
- B60K23/04—Arrangement or mounting of control devices for vehicle transmissions, or parts thereof, not otherwise provided for for differential gearing
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
- E02F9/2267—Valves or distributors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
- F15B1/26—Supply reservoir or sump assemblies
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Fluid-Pressure Circuits (AREA)
- Supply Devices, Intensifiers, Converters, And Telemotors (AREA)
- Operation Control Of Excavators (AREA)
- Component Parts Of Construction Machinery (AREA)
- Forklifts And Lifting Vehicles (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention is directed to a work vehicle having a first hydraulic circuit for controlling various working hydraulic actuators. The first circuit is provided with a hydraulic fluid reservoir having a hydraulic circuit inlet structure that is coaxially aligned with the hydraulic circuit outlet structure so that exhaust hydraulic fluid charges the inlet structure. An annular opening is formed between the inlet and outlet structures for receiving additional hydraulic fluid. The main hydraulic pump is provided with a case drain which directs fluid back to the reservoir through either an oil cooler line or a case drain line having a pressure relief valve. A second hydraulic circuit directs pressurized hydraulic fluid to a hydraulically shiftable transmission. A
branch supply line takes pressurized hydraulic fluid from the transmission pump and directs it to a differential lock pump.
Exhausted fluid from the differential lock pump is returned directly to the transmission pump supply line.
The invention is directed to a work vehicle having a first hydraulic circuit for controlling various working hydraulic actuators. The first circuit is provided with a hydraulic fluid reservoir having a hydraulic circuit inlet structure that is coaxially aligned with the hydraulic circuit outlet structure so that exhaust hydraulic fluid charges the inlet structure. An annular opening is formed between the inlet and outlet structures for receiving additional hydraulic fluid. The main hydraulic pump is provided with a case drain which directs fluid back to the reservoir through either an oil cooler line or a case drain line having a pressure relief valve. A second hydraulic circuit directs pressurized hydraulic fluid to a hydraulically shiftable transmission. A
branch supply line takes pressurized hydraulic fluid from the transmission pump and directs it to a differential lock pump.
Exhausted fluid from the differential lock pump is returned directly to the transmission pump supply line.
Description
HYDRAULIC SYSTEM FOR A WO~K VEHICLE
BACKGROUND QF_r~ INVENTION
1. Field of the Invention:
The invention is directed to a hydraulic system for a work vehicle, such as a grapple skidder.
BACKGROUND QF_r~ INVENTION
1. Field of the Invention:
The invention is directed to a hydraulic system for a work vehicle, such as a grapple skidder.
2. Description of the Prior Art:
Typical work vehicles are self propelled machines that are provided with work implements. The work implements are manipulated by hydraulic actuators such as hydraulic cylinders and rotary hydraulic motors. With a grapple skidder, the working implement is a pair of log gripping tongs located at the rear of the vehicle, and a trail clearing blade located at the front of the vehicle. The vehicle itself is an articulated four-wheel drive tractor that can be operated in relatively rugged terrain.
The front mounted dozer blade is positioned by a hydraulic cylinder. The grapple tongs are positioned by a grapple arch and boom that are manipulated by hydraulic cylinders. The grapple itself maybe rotated by a rotary hydraulic motor, and the grapple tongs closed and opened by a hydraulic cylinder. The vehicle is provided with a variable displacement and/or fixed displacement hydraulic pumps for supplying pressurized hydraulic fluid to the various hydraulic actuators.
The hydraulic pump takes hydraulic fluid from a fluid reservoir and directs it to the various hydraulic assemblies by control valves. The exhausted hydraulic fluid from the actuators and fluid leaking into the case drains of the motors and pumps is returned to the reservoir. As a general rule the reservoir needs to accommodate one third of the fluid volume going through the pump in one minute. In addition, if the reservoir is unpressurized, because different assemblies such as the service brakes require zero back pressure, a charge pump maybe required for charging the main hydraulic pump.
The vehicle maybe provided with spring applied parking brakes and a hydraulically actuated differential lock. Spring applied parking brakes are always biassed into a braking position and are only released through the applications of hydraulic pressure to a single acting hydraulic cylinder. The hydraulically actuated differential lock is triggered by actuating two single acting hydraulic cylinders for locking the front and rear differential of the vehicle.
SUMM~RY
It is one of the objects of the present invention to provide a reservoir for a hydraulic fluid that is smaller than what is typically required.
It is a feature of the present invention, that the exhaust line for the first hydraulic circuit is inserted into a larger inlet line for the pump of the circuit. During normal operating temperatures this configuration provides positive pressure inlet conditions, and in extremely cold operating temperatures this configuration loosens the oil surrounding the inlet and provides very low vacuum conditions.
~herefore, the pump inlet is provided with positive pressure in an unpressurized reservoir. Other advantages include minimizing the aeration of the fluid, permitting the use of a smaller reservoir, and allowing particulate material to settle at the bottom of the reservoir.
It is another object of the present invention to provide a hydraulic fluid cooling circuit.
It is a feature of the hydraulic circuit cooling circuit that a first drain line for the hydraulic fluid pump is coupled to the cooler before being returned to reservoir, and a second drain line is coupled to a pressure relief valve that is coupled to the reservoir.
It is another object of the present invention to provide a simplified circuit for supplying pressurized hydraulic fluid to the differential lock.
It is a feature of the second hydraulic circuit that the transmission charge pump provides pressurized hydraulic fluid to a differential lock hydraulic pump.
In the first hydraulic circuit of the present invention, the hydraulic fluid reservoir is provided with a hydraulic circuit inlet which is mounted to the bottom of the reservoir.
The reservoir is also provided with a hydraulic circuit outlet which directs exhausted hydraulic fluid directly to the hydraulic circuit inlet. The hydraulic circuit outlet comprises a cylindrical tube which is in-}ine with the S hydraulic circuit inlet tube. The outlet tube has a smaller diameter than the inlet tube is located in the forward portion of the inlet tube.
This inlet-outlet tube arrangement acts to inject oil into the inlet. During normal temperature operations positive pressure conditions exist at the inlet in an unpressurized reservoir. In extremely cold temperature operations the outlet oil helps to loosen up the oil entering the inlet a provides very low vacuum conditions.
The size of the reservoir can be reduced as it functions as a surge tank for the hydraulic circuit, storing the oil from retracted hydraulic cylinders. In addition the fluid contents of the reservoir remains calm and particulate material contaminants in the oil settle to the bottom of the reservoir. By projecting the inlet tube upwardly into the reservoir above the bottom of the reservoir, it does not suck in debris that has settled into the bottom of the reservoir.
To assist in cooling the hydraulic fluid, the case drain of the hydraulic fluid pump for the first hydraulic circuit is routed through a cooler before being returned to the reservoir. A relief valve allows oil to bypass the cooler in colder temperatures. When the hydraulic fluid is cold the oil bypasses the cooler, and when the hydraulic fluid is hot, more oil flows through the cooler as it provides less of a pressure drop than the relief valve, as the viscosity of the oil changes with temperature.
In a second hydraulic circuit a second reservoir supplies fluid to a transmission charge pump. The transmission charge pump supplies pressurized hydraulic fluid through a low pressure filter to the hydraulic actuators in a transmission and to a spring applied parking brake circuit. In addition the transmission charge pump directs pressurized hydraulic fluid to a differential lock hydraulic pump. 80th the transmission charge pump and the differential lock pump are fixed displacement pumps. The hydraulic fluid exhausted from the spring applied brake circuit and the differential lock circ.uit is exhausted through a common return line which directs the hydraulic fluid to the inlet of the transmission pump. By using this hydraulic circuitry the spring applied brake circuit is more quickly warmed up in cold weather because the fixed displacement differential lock pump flushes the common return line. In addition back pressure in the common return line is eliminated by directly supplying exhausted fluid from these circuits directly to the inlet of the transmission pump.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side view of a grapple skidder.
Figure 2a and 2b is a hydraulic schematic of the first hydraulic circuit of the grapple skidder.
Figure 3 is a hydraulic schematic of the second hydraulic circuit of the grapple skidder.
Figure 4 is a side view of the hydraulic fluid reservoir for the first hydraulic circuit.
Figure 5 is a front view of the hydraulic fluid reservoir for the first hydraulic circuit.
DETAILED DESCRIPTION
Grapple Skidder Figure 1 illustrates a grapple skidder for which the present inventions are particularly well suited. However these inventions can be used in any number of different applications.
Grapple skidder 10 comprises an articulated frame 12 that is articulated about vertical pivots 14. The skidder is provided with ground engaging means 16 comprising wheels which support and propel the skidder. A dozer blade 18 extends from and is operatively coupled to the skidder. The dozer blade is manipulated by hydraulic actuators 19. Grapple 20 is manipulated by a grapple linkage comprising boom 22 and grapple arch 24. Grapple 20 is attached to boom 22 at the rear of the skidder. The boom is mounted on a grapple arch 24 and is manipulated relative to the grapple arch by hydraulic actuators 26. The grapple arch is manipulated relative to the skidder by hydraulic actuators 28. The tongs of the grapple itself are opened and closed by hydraulic actuator 30.
Hydraulic actuators 19, 28 and 30 are not shown in Figure 1 but are illustrated in the Figure 2b hydraulic schematic. In the illustrated embodiment rotary hydraulic motor 32 is located on top of the boom and is used to rotate the grapple 20, however, the motor could be located inside the grapple head.
First Hydraulic Circuit Reservoir 34 is used to hold hydraulic fluid for the first hydraulic circuit. Hydraulic fluid is placed in the reservoir through fill inlet 36. This inlet is provided with a screen 37 for straining out any debris. Variable displacement pump 38 draws hydraulic fluid from the reservoir 34 through supply line 40 and directs it to supply line 42.
From line 42 the pressurized hydraulic fluid is directed to service brake circuit 100 and priority control circuit 200. A
pressure relief valve 48 is also coupled to supply line 42 for directing pressurized hydraulic fluid back to sump through main return line 50.
The service brake circuit 100 is of a conventional configuration and is similar to the one disclosed in U.S.
Patent 4,898,078, which is incorporated herein by reference.
Pressurized hydraulic fluid is directed to hydraulic pressure accumulator 102. Accumulator 102 is provided with a check valve 104 for preventing the loss of pressurized hydraulic fluid when the pump is shut down. Hydraulic fluid flows through supply line 106 to service brake control valve 108 for applying brake actuators 110. Exhausted fluid exits the braking circuit through control valve 108 to brake return line 112.
Priority control circuit 200 is also of a conventional - 35 configuration and is substantially identical to the one disclosed in U.S. Patent 4,898,078. The priority valve assembly prioritizes fluid flow between the steering circuit and the working circuit. Priority is given to the steering assembly, shutting off flow to the working actuators in response to fluid demands by the steering assembly. The priority valve assembly comprises a spring biassed two-position valve 202 that selectively controls the flow ofpressurized fluid between the steering circuit 204 and the control valve bank 300. Valve 202 is hydraulically balanced between hydraulic fluid pressure sensing lines 206 and 208.
The priority valve assembly is also provided with pressure relief valve 210 which exhausts fluid though return line 212 to reservoir.
The steering circuit 204 is also of a conventional configuration similar to, if not identical to, the one disclosed in U.S. Patent 4,898,078. The steering assembly is provided with a steering control valve and fluid meter, not shown, for controlling the flow of pressurized hydraulic fluid to steering actuators 214. Crossover relief valves, not shown, would also be provided. Exhausted fluid from the steering assembly 204 is directed through return line 216 to main return line 50.
When pressurized hydraulic fluid is directed by the priority assembly to the working actuators it is directed by supply line 302 to control valve bank 300. The valve bank 300 comprises five manually positioned control valves 304, 306, 308, 310 and 312.
The first control valve 304 is used for positioning the dozer blade 18 through hydraulic actuators 19. Control valve 304 is a three-position four-way valve. Fluid from supply line 302 is directed to supply line 314 past check valve 316 to valve 304. Fluid is then directed from control valve 304 through supply/return lines 318 to the actuators 19. Each of the supply/return lines 318 is provided with a pressure relief valve 320 which dump pressurized fluid into main return line 50. Exhausted fluid from the actuators 19 is directed through valve 304 to main return line 50 by return line 322.
Control valves 306 and 308 are identical to and operate in the same manner as control valve 304. As such their corresponding elements are identified with the same numbers.
Control valve 306 positions boom 22 through boom actuators 26, ; and control valve 308 positions grapple arch 24 through grapple actuators 28. Control valve 310 is identical to valves 304, 306 and 308 except it is provided with a detent position 324 for holding the tongs in a locked position.
The operation of the last control val~e 312 is disclosed in U.S. Patent Application Serial No. 07/434,941, filed 9 November 1989, assigned to the assignee of the present invention, and incorporated herein by reference. Control valve 312 controls the rotation of rotary hydraulic motor 32 for rotating the grapple relative to the grapple arch.
Main return line 50 is provided with return filter assembly 80 having filter 82, hydraulically balanced pressure relief valve 84 and hydraulically balanced pressure sensitive electrical switch 86. Hydraulic fluid is typically filtered by the filter and returned to reservoir 34. However, as the filter collects foreign material, the hydraulic pressure drop across the filter increases closing electrical sensing switch 86. Upon the closing of the electrical sensing switch, an indicator light is triggered in the operator's cab of the grapple skidder, alerting the operator that filter 82 should be cleaned or replaced. As the pressure drop continues to increase, because of additional foreign material collected on the filter, pressure relief valve 84 opens thereby providing a hydraulic flow path that bypasses the filter.
Hydraulic Fluid Cooler The pump 38 is provided with two case drain lines 400 and 402. The first case drain line 400 is provided with a hydraulic fluid cooler 404. The second case drain line 402 is provided with a pressure relief valve 406. Both case drain lines are interconnected so that hydraulic fluid can leak from the pump and enter the reservoir through either line. In cold conditions the hydraulic fluid would overcome the pressure setting of the pressure relief valve and pass through line 402 into reservoir. In warmer conditions the fluid would principally pass through the cooler as it would have less of a pressure drop hecause of the change in viscosity with the warmer fluid.
Reservoir Structure The structure of reservoir 34 is best illustrated in Figures 4 and 5. The reservoir comprises an enclosed tank having a bottom wall 500, a top wall 502, two side walls 506 and 508, and front and back walls 510 and 512. Brackets 514 are secured to sidewall 508 for securing the reservoir to the frame of the grapple skidder. Additional mounting assemblies 515 are mounted to the reservoir for mounting various assemblies to the reservoir. Filling inlet 36 is bolted to top wall 502 by bolts 516. Strainer 37 extends downward into the reservoir. The reservoir is also provided with a drain 513 located in bottom wall 500.
As the reservoir is an unpressurized reservoir, it is provided with breathing tube 520. Hydraulic circuit inlet structure 40 is mounted to the bottom wall 500 and extends upwardly therefrom into the reservoir. Inlet structure 40 comprises a cylindrical inlet tube 522, the upper portion 524 of which is flared outwardly at 526. The bottom of the inlet tube is provided with a sealing ring 528. Also mounted to the bottom wall are case drain line 402 and cooler line 400.
The hydraulic circuit outlet structure of the main return line 50 projects through sidewall 506 downwardly into the enlarged upper portion 524 of the inlet tube. The hydraulic circuit outlet structure comprises a cylindrical outlet tube having a smaller diameter than the inlet tube. The outlet tube is coaxially aligned with the inlet tube. In this way the outlet tube injects exhausted fluid into the inlet tube providing a positive pressure at the inlet tube. Make up fluid can be drawn into the inlet tube through the annular opening 530 formed between the outlet tube and the inlet tube.
Second Hydraulic Circuit The second hydraulic circuit is best illustrated in Figure 3, this circuit comprises a reservoir 600 for supplying hydraulic fluid to transmission charge pump 602 and differential lock pump 604. Transmission charge pump 602 draws fluid from reservoir 600 through a hydraulic circuit inlet into transmission pump supply line 606 and straining screen 608. Pump 602 then directs pressurized hydraulic fluid into transmission supply line 610 through low pressure filter 612 to hydraulically shiftable transmission 614.
Branched off of line 610 is supply line 616 which directs pressurized hydraulic fluid to the control valve 618 for a spring applied parking brake. The spring applied parking brake is normally closed by a spring and is released by applying hydraulic pressure to compress the spring, releasing the brake. The brake release actuator is a single acting hydraulic cylinder. Control valve 618 is a solenoid actuated valve that is controlled by a park brake control electric circuit. In the position illustrated in Figure 3, the parking brake is applied, as the flow of pressurized hydraulic fluid to the brake is prevented by valve 618.
When valve 618 is shifted by the control circuit, pressurized hydraulic fluid is directed to ports 620, 622 and 624 by supply/return lines 626, 628 and 630, respectively.
Port 620 is a gauge port for monitoring pressure in supply lines 626, 628 and 630; port 622 is used to trigger a switch for alerting the operator the parking brake is applied; and port 624 is coupled to the single acting hydraulic cylinder for releasing the spring applied parking brake.
When ~ontrol valve 618 is shifted into the position illustrated in Figure 3, the fluid is drained through return lines 632 and 634 which return the exhausted fluid to the inlet of the transmission charge pump.
One of the most unique features of the second hydraulic circuit is that the supply line 636 of the differential lock pump 604 is coupled to supply line 616 of transmission charge pump 602. In this way the differential lock pump is provided hydraulic fluid under a positive pressure and which has already been filtered by low pressure filter 612.
Pressurized hydraulic fluid is directed by pump 604 though supply line 638 to differential lock control valve 640.
Control valve 640 is a solenoid actuated valve which is j ~J ~
triggered by a switch in the operator's cab. In the embodiment illustrated in Figure 3, the differential lock is not actuated and the pressurized hydraulic fluid is directed by control valve 640 through return line 634 to supply line 5 606 of pump 602.
If an operator shifts control valve 640 by closing the switch in the operator's cab, the control valve is shifted so that pressurized hydraulic fluid is directed to supply/return lines 642, 644 and 646 for directing pressurized hydraulic fluid to ports 648, 650 and 652, respectively. Port 648 is a test port for testing the hydraulic pressure in supply/return lines 642, 644 and 646; and ports 650 and 652 are for applying pressurized hydraulic fluid to the front and rear differential locks.
As with the spring applied parking brake, the differential lock actuators are single acting hydraulic cylinders. Pressure relief valve 654 is used to maintain appropriate hydraulic pressure in supply line 638. When the differential locks are released, as illustrated in Figure 3, hydraulic fluid in supply/return lines 642, 644 and 646 is directed by control valve 640 to return line 632.
The above described hydraulic system should not be limited by the disclosed embodiments, but should be limited solely by the claims that follow.
Typical work vehicles are self propelled machines that are provided with work implements. The work implements are manipulated by hydraulic actuators such as hydraulic cylinders and rotary hydraulic motors. With a grapple skidder, the working implement is a pair of log gripping tongs located at the rear of the vehicle, and a trail clearing blade located at the front of the vehicle. The vehicle itself is an articulated four-wheel drive tractor that can be operated in relatively rugged terrain.
The front mounted dozer blade is positioned by a hydraulic cylinder. The grapple tongs are positioned by a grapple arch and boom that are manipulated by hydraulic cylinders. The grapple itself maybe rotated by a rotary hydraulic motor, and the grapple tongs closed and opened by a hydraulic cylinder. The vehicle is provided with a variable displacement and/or fixed displacement hydraulic pumps for supplying pressurized hydraulic fluid to the various hydraulic actuators.
The hydraulic pump takes hydraulic fluid from a fluid reservoir and directs it to the various hydraulic assemblies by control valves. The exhausted hydraulic fluid from the actuators and fluid leaking into the case drains of the motors and pumps is returned to the reservoir. As a general rule the reservoir needs to accommodate one third of the fluid volume going through the pump in one minute. In addition, if the reservoir is unpressurized, because different assemblies such as the service brakes require zero back pressure, a charge pump maybe required for charging the main hydraulic pump.
The vehicle maybe provided with spring applied parking brakes and a hydraulically actuated differential lock. Spring applied parking brakes are always biassed into a braking position and are only released through the applications of hydraulic pressure to a single acting hydraulic cylinder. The hydraulically actuated differential lock is triggered by actuating two single acting hydraulic cylinders for locking the front and rear differential of the vehicle.
SUMM~RY
It is one of the objects of the present invention to provide a reservoir for a hydraulic fluid that is smaller than what is typically required.
It is a feature of the present invention, that the exhaust line for the first hydraulic circuit is inserted into a larger inlet line for the pump of the circuit. During normal operating temperatures this configuration provides positive pressure inlet conditions, and in extremely cold operating temperatures this configuration loosens the oil surrounding the inlet and provides very low vacuum conditions.
~herefore, the pump inlet is provided with positive pressure in an unpressurized reservoir. Other advantages include minimizing the aeration of the fluid, permitting the use of a smaller reservoir, and allowing particulate material to settle at the bottom of the reservoir.
It is another object of the present invention to provide a hydraulic fluid cooling circuit.
It is a feature of the hydraulic circuit cooling circuit that a first drain line for the hydraulic fluid pump is coupled to the cooler before being returned to reservoir, and a second drain line is coupled to a pressure relief valve that is coupled to the reservoir.
It is another object of the present invention to provide a simplified circuit for supplying pressurized hydraulic fluid to the differential lock.
It is a feature of the second hydraulic circuit that the transmission charge pump provides pressurized hydraulic fluid to a differential lock hydraulic pump.
In the first hydraulic circuit of the present invention, the hydraulic fluid reservoir is provided with a hydraulic circuit inlet which is mounted to the bottom of the reservoir.
The reservoir is also provided with a hydraulic circuit outlet which directs exhausted hydraulic fluid directly to the hydraulic circuit inlet. The hydraulic circuit outlet comprises a cylindrical tube which is in-}ine with the S hydraulic circuit inlet tube. The outlet tube has a smaller diameter than the inlet tube is located in the forward portion of the inlet tube.
This inlet-outlet tube arrangement acts to inject oil into the inlet. During normal temperature operations positive pressure conditions exist at the inlet in an unpressurized reservoir. In extremely cold temperature operations the outlet oil helps to loosen up the oil entering the inlet a provides very low vacuum conditions.
The size of the reservoir can be reduced as it functions as a surge tank for the hydraulic circuit, storing the oil from retracted hydraulic cylinders. In addition the fluid contents of the reservoir remains calm and particulate material contaminants in the oil settle to the bottom of the reservoir. By projecting the inlet tube upwardly into the reservoir above the bottom of the reservoir, it does not suck in debris that has settled into the bottom of the reservoir.
To assist in cooling the hydraulic fluid, the case drain of the hydraulic fluid pump for the first hydraulic circuit is routed through a cooler before being returned to the reservoir. A relief valve allows oil to bypass the cooler in colder temperatures. When the hydraulic fluid is cold the oil bypasses the cooler, and when the hydraulic fluid is hot, more oil flows through the cooler as it provides less of a pressure drop than the relief valve, as the viscosity of the oil changes with temperature.
In a second hydraulic circuit a second reservoir supplies fluid to a transmission charge pump. The transmission charge pump supplies pressurized hydraulic fluid through a low pressure filter to the hydraulic actuators in a transmission and to a spring applied parking brake circuit. In addition the transmission charge pump directs pressurized hydraulic fluid to a differential lock hydraulic pump. 80th the transmission charge pump and the differential lock pump are fixed displacement pumps. The hydraulic fluid exhausted from the spring applied brake circuit and the differential lock circ.uit is exhausted through a common return line which directs the hydraulic fluid to the inlet of the transmission pump. By using this hydraulic circuitry the spring applied brake circuit is more quickly warmed up in cold weather because the fixed displacement differential lock pump flushes the common return line. In addition back pressure in the common return line is eliminated by directly supplying exhausted fluid from these circuits directly to the inlet of the transmission pump.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side view of a grapple skidder.
Figure 2a and 2b is a hydraulic schematic of the first hydraulic circuit of the grapple skidder.
Figure 3 is a hydraulic schematic of the second hydraulic circuit of the grapple skidder.
Figure 4 is a side view of the hydraulic fluid reservoir for the first hydraulic circuit.
Figure 5 is a front view of the hydraulic fluid reservoir for the first hydraulic circuit.
DETAILED DESCRIPTION
Grapple Skidder Figure 1 illustrates a grapple skidder for which the present inventions are particularly well suited. However these inventions can be used in any number of different applications.
Grapple skidder 10 comprises an articulated frame 12 that is articulated about vertical pivots 14. The skidder is provided with ground engaging means 16 comprising wheels which support and propel the skidder. A dozer blade 18 extends from and is operatively coupled to the skidder. The dozer blade is manipulated by hydraulic actuators 19. Grapple 20 is manipulated by a grapple linkage comprising boom 22 and grapple arch 24. Grapple 20 is attached to boom 22 at the rear of the skidder. The boom is mounted on a grapple arch 24 and is manipulated relative to the grapple arch by hydraulic actuators 26. The grapple arch is manipulated relative to the skidder by hydraulic actuators 28. The tongs of the grapple itself are opened and closed by hydraulic actuator 30.
Hydraulic actuators 19, 28 and 30 are not shown in Figure 1 but are illustrated in the Figure 2b hydraulic schematic. In the illustrated embodiment rotary hydraulic motor 32 is located on top of the boom and is used to rotate the grapple 20, however, the motor could be located inside the grapple head.
First Hydraulic Circuit Reservoir 34 is used to hold hydraulic fluid for the first hydraulic circuit. Hydraulic fluid is placed in the reservoir through fill inlet 36. This inlet is provided with a screen 37 for straining out any debris. Variable displacement pump 38 draws hydraulic fluid from the reservoir 34 through supply line 40 and directs it to supply line 42.
From line 42 the pressurized hydraulic fluid is directed to service brake circuit 100 and priority control circuit 200. A
pressure relief valve 48 is also coupled to supply line 42 for directing pressurized hydraulic fluid back to sump through main return line 50.
The service brake circuit 100 is of a conventional configuration and is similar to the one disclosed in U.S.
Patent 4,898,078, which is incorporated herein by reference.
Pressurized hydraulic fluid is directed to hydraulic pressure accumulator 102. Accumulator 102 is provided with a check valve 104 for preventing the loss of pressurized hydraulic fluid when the pump is shut down. Hydraulic fluid flows through supply line 106 to service brake control valve 108 for applying brake actuators 110. Exhausted fluid exits the braking circuit through control valve 108 to brake return line 112.
Priority control circuit 200 is also of a conventional - 35 configuration and is substantially identical to the one disclosed in U.S. Patent 4,898,078. The priority valve assembly prioritizes fluid flow between the steering circuit and the working circuit. Priority is given to the steering assembly, shutting off flow to the working actuators in response to fluid demands by the steering assembly. The priority valve assembly comprises a spring biassed two-position valve 202 that selectively controls the flow ofpressurized fluid between the steering circuit 204 and the control valve bank 300. Valve 202 is hydraulically balanced between hydraulic fluid pressure sensing lines 206 and 208.
The priority valve assembly is also provided with pressure relief valve 210 which exhausts fluid though return line 212 to reservoir.
The steering circuit 204 is also of a conventional configuration similar to, if not identical to, the one disclosed in U.S. Patent 4,898,078. The steering assembly is provided with a steering control valve and fluid meter, not shown, for controlling the flow of pressurized hydraulic fluid to steering actuators 214. Crossover relief valves, not shown, would also be provided. Exhausted fluid from the steering assembly 204 is directed through return line 216 to main return line 50.
When pressurized hydraulic fluid is directed by the priority assembly to the working actuators it is directed by supply line 302 to control valve bank 300. The valve bank 300 comprises five manually positioned control valves 304, 306, 308, 310 and 312.
The first control valve 304 is used for positioning the dozer blade 18 through hydraulic actuators 19. Control valve 304 is a three-position four-way valve. Fluid from supply line 302 is directed to supply line 314 past check valve 316 to valve 304. Fluid is then directed from control valve 304 through supply/return lines 318 to the actuators 19. Each of the supply/return lines 318 is provided with a pressure relief valve 320 which dump pressurized fluid into main return line 50. Exhausted fluid from the actuators 19 is directed through valve 304 to main return line 50 by return line 322.
Control valves 306 and 308 are identical to and operate in the same manner as control valve 304. As such their corresponding elements are identified with the same numbers.
Control valve 306 positions boom 22 through boom actuators 26, ; and control valve 308 positions grapple arch 24 through grapple actuators 28. Control valve 310 is identical to valves 304, 306 and 308 except it is provided with a detent position 324 for holding the tongs in a locked position.
The operation of the last control val~e 312 is disclosed in U.S. Patent Application Serial No. 07/434,941, filed 9 November 1989, assigned to the assignee of the present invention, and incorporated herein by reference. Control valve 312 controls the rotation of rotary hydraulic motor 32 for rotating the grapple relative to the grapple arch.
Main return line 50 is provided with return filter assembly 80 having filter 82, hydraulically balanced pressure relief valve 84 and hydraulically balanced pressure sensitive electrical switch 86. Hydraulic fluid is typically filtered by the filter and returned to reservoir 34. However, as the filter collects foreign material, the hydraulic pressure drop across the filter increases closing electrical sensing switch 86. Upon the closing of the electrical sensing switch, an indicator light is triggered in the operator's cab of the grapple skidder, alerting the operator that filter 82 should be cleaned or replaced. As the pressure drop continues to increase, because of additional foreign material collected on the filter, pressure relief valve 84 opens thereby providing a hydraulic flow path that bypasses the filter.
Hydraulic Fluid Cooler The pump 38 is provided with two case drain lines 400 and 402. The first case drain line 400 is provided with a hydraulic fluid cooler 404. The second case drain line 402 is provided with a pressure relief valve 406. Both case drain lines are interconnected so that hydraulic fluid can leak from the pump and enter the reservoir through either line. In cold conditions the hydraulic fluid would overcome the pressure setting of the pressure relief valve and pass through line 402 into reservoir. In warmer conditions the fluid would principally pass through the cooler as it would have less of a pressure drop hecause of the change in viscosity with the warmer fluid.
Reservoir Structure The structure of reservoir 34 is best illustrated in Figures 4 and 5. The reservoir comprises an enclosed tank having a bottom wall 500, a top wall 502, two side walls 506 and 508, and front and back walls 510 and 512. Brackets 514 are secured to sidewall 508 for securing the reservoir to the frame of the grapple skidder. Additional mounting assemblies 515 are mounted to the reservoir for mounting various assemblies to the reservoir. Filling inlet 36 is bolted to top wall 502 by bolts 516. Strainer 37 extends downward into the reservoir. The reservoir is also provided with a drain 513 located in bottom wall 500.
As the reservoir is an unpressurized reservoir, it is provided with breathing tube 520. Hydraulic circuit inlet structure 40 is mounted to the bottom wall 500 and extends upwardly therefrom into the reservoir. Inlet structure 40 comprises a cylindrical inlet tube 522, the upper portion 524 of which is flared outwardly at 526. The bottom of the inlet tube is provided with a sealing ring 528. Also mounted to the bottom wall are case drain line 402 and cooler line 400.
The hydraulic circuit outlet structure of the main return line 50 projects through sidewall 506 downwardly into the enlarged upper portion 524 of the inlet tube. The hydraulic circuit outlet structure comprises a cylindrical outlet tube having a smaller diameter than the inlet tube. The outlet tube is coaxially aligned with the inlet tube. In this way the outlet tube injects exhausted fluid into the inlet tube providing a positive pressure at the inlet tube. Make up fluid can be drawn into the inlet tube through the annular opening 530 formed between the outlet tube and the inlet tube.
Second Hydraulic Circuit The second hydraulic circuit is best illustrated in Figure 3, this circuit comprises a reservoir 600 for supplying hydraulic fluid to transmission charge pump 602 and differential lock pump 604. Transmission charge pump 602 draws fluid from reservoir 600 through a hydraulic circuit inlet into transmission pump supply line 606 and straining screen 608. Pump 602 then directs pressurized hydraulic fluid into transmission supply line 610 through low pressure filter 612 to hydraulically shiftable transmission 614.
Branched off of line 610 is supply line 616 which directs pressurized hydraulic fluid to the control valve 618 for a spring applied parking brake. The spring applied parking brake is normally closed by a spring and is released by applying hydraulic pressure to compress the spring, releasing the brake. The brake release actuator is a single acting hydraulic cylinder. Control valve 618 is a solenoid actuated valve that is controlled by a park brake control electric circuit. In the position illustrated in Figure 3, the parking brake is applied, as the flow of pressurized hydraulic fluid to the brake is prevented by valve 618.
When valve 618 is shifted by the control circuit, pressurized hydraulic fluid is directed to ports 620, 622 and 624 by supply/return lines 626, 628 and 630, respectively.
Port 620 is a gauge port for monitoring pressure in supply lines 626, 628 and 630; port 622 is used to trigger a switch for alerting the operator the parking brake is applied; and port 624 is coupled to the single acting hydraulic cylinder for releasing the spring applied parking brake.
When ~ontrol valve 618 is shifted into the position illustrated in Figure 3, the fluid is drained through return lines 632 and 634 which return the exhausted fluid to the inlet of the transmission charge pump.
One of the most unique features of the second hydraulic circuit is that the supply line 636 of the differential lock pump 604 is coupled to supply line 616 of transmission charge pump 602. In this way the differential lock pump is provided hydraulic fluid under a positive pressure and which has already been filtered by low pressure filter 612.
Pressurized hydraulic fluid is directed by pump 604 though supply line 638 to differential lock control valve 640.
Control valve 640 is a solenoid actuated valve which is j ~J ~
triggered by a switch in the operator's cab. In the embodiment illustrated in Figure 3, the differential lock is not actuated and the pressurized hydraulic fluid is directed by control valve 640 through return line 634 to supply line 5 606 of pump 602.
If an operator shifts control valve 640 by closing the switch in the operator's cab, the control valve is shifted so that pressurized hydraulic fluid is directed to supply/return lines 642, 644 and 646 for directing pressurized hydraulic fluid to ports 648, 650 and 652, respectively. Port 648 is a test port for testing the hydraulic pressure in supply/return lines 642, 644 and 646; and ports 650 and 652 are for applying pressurized hydraulic fluid to the front and rear differential locks.
As with the spring applied parking brake, the differential lock actuators are single acting hydraulic cylinders. Pressure relief valve 654 is used to maintain appropriate hydraulic pressure in supply line 638. When the differential locks are released, as illustrated in Figure 3, hydraulic fluid in supply/return lines 642, 644 and 646 is directed by control valve 640 to return line 632.
The above described hydraulic system should not be limited by the disclosed embodiments, but should be limited solely by the claims that follow.
Claims (25)
1. A hydraulic fluid reservoir comprising a tank for holding hydraulic fluid, the tank having a bottom wall, a top wall, a front wall, a back wall, and enclosing side walls ;
a hydraulic system inlet structure for supplying hydraulic fluid from the tank to a hydraulic circuit, the inlet structure is mounted to the tank and projects upwardly and inwardly into the tank;
a hydraulic system outlet structure for returning exhausted hydraulic fluid from a hydraulic circuit to the tank, the outlet structure is mounted to the tank and projects downwardly and inwardly into the tank;
whereby the outlet structure is coaxially aligned with the inlet structure for directing exhausted hydraulic fluid into the inlet structure, the outlet structure and the inlet structure defining an opening for drawing additional hydraulic fluid from the tank into the inlet structure.
a hydraulic system inlet structure for supplying hydraulic fluid from the tank to a hydraulic circuit, the inlet structure is mounted to the tank and projects upwardly and inwardly into the tank;
a hydraulic system outlet structure for returning exhausted hydraulic fluid from a hydraulic circuit to the tank, the outlet structure is mounted to the tank and projects downwardly and inwardly into the tank;
whereby the outlet structure is coaxially aligned with the inlet structure for directing exhausted hydraulic fluid into the inlet structure, the outlet structure and the inlet structure defining an opening for drawing additional hydraulic fluid from the tank into the inlet structure.
2. A hydraulic fluid reservoir as defined by claim 1 wherein a portion of the outlet structure projects into a portion of the inlet structure.
3. A hydraulic fluid reservoir as defined by claim 2 wherein the opening comprises an annular opening formed between the outlet structure and the inlet structure.
4. A hydraulic fluid reservoir as defined by claim 3 wherein the inlet structure comprises a cylindrical inlet tube.
5. A hydraulic fluid reservoir as defined by claim 4 wherein the outlet structure comprises a cylindrical outlet tube.
6. A hydraulic fluid reservoir as defined by claim 5 wherein the inlet tube is flared outwardly for accepting that portion of the outlet tube that projects into the inlet tube.
7. A hydraulic fluid reservoir as defined by claim 6 wherein the inlet tube is mounted to the bottom wall of the tank and projects upwardly from the bottom wall.
8 A hydraulic fluid reservoir as defined by claim 7 wherein the bottom wall of the tank is provided with a case drain line inlet.
9. A hydraulic fluid reservoir as defined by claim 8 wherein the bottom wall of the tank is provided with a oil cooler inlet.
10. A hydraulic fluid reservoir as defined by claim 1 wherein the reservoir is unpressurized and provided with a breathing tube.
11. A work vehicle for performing a work operation, the vehicle having a supporting structure to which is mounted ground engaging means for supporting and propelling the vehicle, the vehicle is also provided with a work implement for performing a work operation, the vehicle further comprising:
a hydraulic fluid reservoir for holding hydraulic fluid, the reservoir having an inlet structure and an outlet structure, the outlet structure being coaxially aligned with the inlet structure for directing exhausted hydraulic fluid into the inlet structure, the outlet structure and the inlet structure defining an opening for drawing hydraulic fluid from the reservoir into the inlet structure;
a hydraulic fluid pump for supplying pressurized hydraulic fluid, the hydraulic pump is fluidly coupled to the inlet structure;
a hydraulic actuator for manipulating the work implement, the hydraulic actuator is fluidly coupled to the hydraulic pump for receiving pressurized hydraulic fluid, the hydraulic actuator is also fluidly coupled to the outlet structure for returning exhausted hydraulic fluid to the reservoir.
a hydraulic fluid reservoir for holding hydraulic fluid, the reservoir having an inlet structure and an outlet structure, the outlet structure being coaxially aligned with the inlet structure for directing exhausted hydraulic fluid into the inlet structure, the outlet structure and the inlet structure defining an opening for drawing hydraulic fluid from the reservoir into the inlet structure;
a hydraulic fluid pump for supplying pressurized hydraulic fluid, the hydraulic pump is fluidly coupled to the inlet structure;
a hydraulic actuator for manipulating the work implement, the hydraulic actuator is fluidly coupled to the hydraulic pump for receiving pressurized hydraulic fluid, the hydraulic actuator is also fluidly coupled to the outlet structure for returning exhausted hydraulic fluid to the reservoir.
12. A work vehicle as defined by claim 11 wherein a portion of the outlet structure projects into a portion of the inlet structure.
13. A work vehicle as defined by claim 12 wherein the opening comprises an annular opening formed between the outlet structure and the inlet structure.
14. A work vehicle as defined by claim 13 wherein the inlet structure comprises a cylindrical inlet tube and the outlet structure comprises a cylindrical outlet tube.
15. A work vehicle as defined by claim 14 wherein the inlet tube is flared outwardly for accepting that portion of the outlet tube that projects into the inlet tube.
16. A work vehicle as defined by claim 15 wherein the hydraulic fluid pump is a variable displacement pump.
17. A work vehicle as defined by claim 16 wherein the reservoir is unpressurized and is provided with a breathing tube.
18. A work vehicle as defined by claim 11 wherein the hydraulic pump is provided with a case drain for receiving hydraulic fluid leaking from the pump, the case drain is fluidly coupled to an oil cooler line having an oil cooler, the oil cooler line directs oil from the case drain through the oil cooler back to the reservoir.
19. A work vehicle as defined by claim 18 wherein the case drain is also fluidly coupled to a case drain line having a pressure relief valve with a hydraulic pressure setting, the case drain line directs fluid through the pressure relief line back to reservoir if the hydraulic pressure in the case drain line exceeds the hydraulic pressure setting of the pressure relief valve, the oil cooler line and the case drain line are interconnected by the case drain so that hydraulic fluid from the case drain may flow to reservoir through either the case drain line or the oil cooler line.
20. A work vehicle for performing a work operation, the vehicle having a supporting structure to which is mounted ground engaging means for supporting and propelling the vehicle, the vehicle is also provided with a work implement for performing a work operation, the vehicle further comprising:
a hydraulic fluid reservoir for holding hydraulic fluid, the reservoir having an inlet structure and an outlet structure;
a hydraulic fluid pump for supplying pressurized hydraulic fluid, the hydraulic pump is fluidly coupled to the inlet structure and is provided with a case drain for receiving hydraulic fluid leaking from the pump;
a hydraulic actuator for manipulating the work implement, the hydraulic actuator is fluidly coupled to the hydraulic pump for receiving pressurized hydraulic fluid, the hydraulic actuator is also fluidly coupled to the outlet structure for returning exhausted hydraulic fluid to the reservoir;
an oil cooler line fluidly coupled to the case drain, the oil cooler line having an oil cooler, the oil cooler line directing oil from the case drain through the oil cooler back to the reservoir; and a case drain line fluidly coupled to the case drain, the case drain line having a pressure relief valve with a hydraulic pressure setting, the case drain line directs fluid through the pressure relief line back to reservoir if the hydraulic pressure in the case drain line exceeds the hydraulic pressure setting of the pressure relief valve, the oil cooler line and the case drain line are interconnected by the case drain so that hydraulic fluid from the case drain may flow to reservoir through either the case drain line or the oil cooler line.
a hydraulic fluid reservoir for holding hydraulic fluid, the reservoir having an inlet structure and an outlet structure;
a hydraulic fluid pump for supplying pressurized hydraulic fluid, the hydraulic pump is fluidly coupled to the inlet structure and is provided with a case drain for receiving hydraulic fluid leaking from the pump;
a hydraulic actuator for manipulating the work implement, the hydraulic actuator is fluidly coupled to the hydraulic pump for receiving pressurized hydraulic fluid, the hydraulic actuator is also fluidly coupled to the outlet structure for returning exhausted hydraulic fluid to the reservoir;
an oil cooler line fluidly coupled to the case drain, the oil cooler line having an oil cooler, the oil cooler line directing oil from the case drain through the oil cooler back to the reservoir; and a case drain line fluidly coupled to the case drain, the case drain line having a pressure relief valve with a hydraulic pressure setting, the case drain line directs fluid through the pressure relief line back to reservoir if the hydraulic pressure in the case drain line exceeds the hydraulic pressure setting of the pressure relief valve, the oil cooler line and the case drain line are interconnected by the case drain so that hydraulic fluid from the case drain may flow to reservoir through either the case drain line or the oil cooler line.
21. A hydraulic circuit comprising a hydraulic fluid reservoir for holding hydraulic fluid, the reservoir having an inlet structure and an outlet structure;
a hydraulic fluid pump for supplying pressurized hydraulic fluid, the hydraulic pump is fluidly coupled to the inlet structure and is provided with a case drain for receiving hydraulic fluid leaking from the pump;
a hydraulic actuator for manipulating the work implement, the hydraulic actuator is fluidly coupled to the hydraulic pump for receiving pressurized hydraulic fluid, the hydraulic actuator is also fluidly coupled to the outlet structure for returning exhausted hydraulic fluid to the reservoir; and an oil cooler line fluidly coupled to the case drain, the oil cooler line having an oil cooler, the oil cooler line directing oil from the case drain through the oil cooler back to the reservoir.
a hydraulic fluid pump for supplying pressurized hydraulic fluid, the hydraulic pump is fluidly coupled to the inlet structure and is provided with a case drain for receiving hydraulic fluid leaking from the pump;
a hydraulic actuator for manipulating the work implement, the hydraulic actuator is fluidly coupled to the hydraulic pump for receiving pressurized hydraulic fluid, the hydraulic actuator is also fluidly coupled to the outlet structure for returning exhausted hydraulic fluid to the reservoir; and an oil cooler line fluidly coupled to the case drain, the oil cooler line having an oil cooler, the oil cooler line directing oil from the case drain through the oil cooler back to the reservoir.
22. A hydraulic circuit as defined by claim 21 further comprising a case drain line fluidly coupled to the case drain, the case drain line having a pressure relief valve with a hydraulic pressure setting, the case drain line directs fluid through the pressure relief line back to reservoir if the hydraulic pressure in the case drain line exceeds the hydraulic pressure setting of the pressure relief valve, the oil cooler line and the case drain line are interconnected by the case drain so that hydraulic fluid from the case drain may flow to reservoir through either the case drain line or the oil cooler line.
23. A work vehicle for performing a work operation, the vehicle having a supporting structure to which is mounted ground engaging means for supporting and propelling the vehicle, the vehicle is provided with a hydraulically shiftable transmission for driving the ground engaging means through a differential, the vehicle further comprising:
a hydraulic fluid reservoir for holding hydraulic fluid, the reservoir having a hydraulic circuit inlet;
a hydraulic fluid transmission pump for supplying pressurized hydraulic fluid to the hydraulically shiftable transmission through a transmission supply line, the transmission pump is fluidly coupled to the hydraulic circuit inlet by a transmission pump supply line for receiving hydraulic fluid from the reservoir;
a hydraulically actuated differential lock for locking the differential;
a hydraulic fluid differential lock pump for supplying pressurized hydraulic fluid to the differential lock, the differential lock pump is fluidly coupled to the transmission pump for receiving pressurized hydraulic fluid from the transmission pump.
a hydraulic fluid reservoir for holding hydraulic fluid, the reservoir having a hydraulic circuit inlet;
a hydraulic fluid transmission pump for supplying pressurized hydraulic fluid to the hydraulically shiftable transmission through a transmission supply line, the transmission pump is fluidly coupled to the hydraulic circuit inlet by a transmission pump supply line for receiving hydraulic fluid from the reservoir;
a hydraulically actuated differential lock for locking the differential;
a hydraulic fluid differential lock pump for supplying pressurized hydraulic fluid to the differential lock, the differential lock pump is fluidly coupled to the transmission pump for receiving pressurized hydraulic fluid from the transmission pump.
24. A work vehicle as defined by claim 23 wherein the transmission supply line is provided with a fluid filter and the differential lock pump is fluidly coupled to the transmission supply line so that pressurized hydraulic fluid from the transmission pump is first filtered before being supplied to the differential lock pump.
25. A work vehicle as defined by claim 24 wherein exhausted fluid from the differential lock is directed to the transmission pump supply line.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US55974690A | 1990-07-30 | 1990-07-30 | |
| US07/559,746 | 1990-07-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2047305A1 true CA2047305A1 (en) | 1992-01-31 |
Family
ID=24234848
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2047305 Abandoned CA2047305A1 (en) | 1990-07-30 | 1991-07-17 | Hydraulic system for a work vehicle |
Country Status (3)
| Country | Link |
|---|---|
| EP (2) | EP0469417A1 (en) |
| JP (1) | JPH05118301A (en) |
| CA (1) | CA2047305A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5895099A (en) * | 1997-10-17 | 1999-04-20 | Deere & Company | Hydraulic structure for a brake system |
| EP2154016A1 (en) * | 2008-08-14 | 2010-02-17 | Desider Boda | Drive system with cooling device for hybrid vehicles |
| US10066644B2 (en) | 2016-03-10 | 2018-09-04 | Caterpilllar Forest Products Inc. | Forestry grapple with high pressure protection system |
| CN110454449A (en) * | 2019-08-26 | 2019-11-15 | 徐工集团工程机械有限公司 | An embedded integral hydraulic oil tank and fire truck |
| CN110748513A (en) * | 2019-12-09 | 2020-02-04 | 湖南响箭重工科技有限公司 | Hydraulic oil tank structure for concrete pump truck |
| CN115450278B (en) * | 2022-09-16 | 2023-09-22 | 江苏电子信息职业学院 | Auxiliary shoveling control method for loader bucket |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2251664A (en) * | 1936-06-20 | 1941-08-05 | Francis W Davis | Liquid circulating system |
| US2316729A (en) * | 1941-06-30 | 1943-04-13 | Napler & Son Ltd D | Tank for use in aircraft |
| FR940929A (en) * | 1944-05-15 | 1948-12-28 | Vickers Armstrongs Ltd | Further training in liquid supply systems for circulation of liquids under pressure |
| US2588778A (en) * | 1944-12-15 | 1952-03-11 | Tibeau Clement | Oil tank hopper by-pass control |
| US2588788A (en) * | 1949-11-12 | 1952-03-11 | Parker R Zell | Automatically actuated fire extinguisher |
| US2767736A (en) * | 1953-03-25 | 1956-10-23 | Frank P Lackinger | Fluid pickup |
| US2962863A (en) * | 1956-02-01 | 1960-12-06 | Caroli Gerhard | Device for degassing pressure fluids of hydraulic power plants |
| US3002355A (en) * | 1958-02-04 | 1961-10-03 | Yale & Towne Mfg Co | Reservoir for hydraulic system |
| FR1231900A (en) * | 1958-06-19 | 1960-10-04 | Zahnradfabrik Friedrichshafen | Hydraulic device such as a cylinder, in particular for agricultural tractors |
| US4203287A (en) * | 1979-03-09 | 1980-05-20 | General Motors Corporation | Power steering hydraulic system with a low pressure expansible reservoir |
| WO1981000600A1 (en) * | 1979-08-30 | 1981-03-05 | Caterpillar Tractor Co | Lock valve with variable length piston and hydraulic system for a work implement using the same |
| DE3107998A1 (en) * | 1981-03-03 | 1982-10-07 | Volkswagenwerk Ag, 3180 Wolfsburg | Control device for a motor vehicle automatic transmission |
| US4570509A (en) * | 1983-06-13 | 1986-02-18 | Deere & Company | Differential lock control system responsive to steering and/or braking action to unlock differential |
| EP0141005A1 (en) * | 1983-10-24 | 1985-05-15 | CARLO GRAZIANO S.p.A. TORINO | Gearbox with hydraulically-operated multiple-disc clutches |
| US4898078A (en) * | 1987-09-11 | 1990-02-06 | Deere & Company | Hydraulic system for a work vehicle |
-
1991
- 1991-07-17 CA CA 2047305 patent/CA2047305A1/en not_active Abandoned
- 1991-07-20 EP EP91112174A patent/EP0469417A1/en not_active Withdrawn
- 1991-07-20 EP EP91112173A patent/EP0469416A1/en not_active Withdrawn
- 1991-07-30 JP JP3190054A patent/JPH05118301A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0469417A1 (en) | 1992-02-05 |
| JPH05118301A (en) | 1993-05-14 |
| EP0469416A1 (en) | 1992-02-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |