US3472127A - Control circuit for bulldozers used in pushing - Google Patents

Control circuit for bulldozers used in pushing Download PDF

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Publication number
US3472127A
US3472127A US689924A US3472127DA US3472127A US 3472127 A US3472127 A US 3472127A US 689924 A US689924 A US 689924A US 3472127D A US3472127D A US 3472127DA US 3472127 A US3472127 A US 3472127A
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United States
Prior art keywords
blade
valve
jack
control circuit
pushing
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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.)
Expired - Lifetime
Application number
US689924A
Inventor
James E Scheidt
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Caterpillar Inc
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Caterpillar Tractor Co
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Publication of US3472127A publication Critical patent/US3472127A/en
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    • 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
    • E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
    • 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3122—Special positions other than the pump port being connected to working ports or the working ports being connected to the return line
    • F15B2211/3127—Floating position connecting the working ports and the return line
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
    • F15B2211/5154—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve being connected to multiple ports of an output member

Definitions

  • Hydraulically actuated bulldozers usually have conventional controls including a manually actuated valve with raise and lower positions, a neutral or hold position in which the blade is hydraulically locked in any selected attitude and a float position which interconnects the pump reservoir and operative ends of the bulldozer jack so that the blade is free to float or move upwardly or downwardly in response to gravity or other external forces.
  • a further object is to provide a circuit including auxiliary valve means to establish a semi-float position of a bulldozer blade in which the blade is free to move up wardly and can be moved downwardly by external forces which exceed the force of gravity normally causing the blade to drop.
  • the drawing is a schematic view of a bulldozer blade control circuit embodying the present invention and illustrating the blade in contact with a push block.
  • a conventional circuit includes a hydraulic jack, generally indicated at 10, for raising and lowering a bulldozer blade 11. Fluid from a reservoir 12 is directed selectively to opposite ends of this jack by a pump 13 and a manually actuated control valve 14 having raise, hold, lower and float positions as above described.
  • a conventional relief valve 15 prevents overloading of the circuit and lines 16 and 17 communicate with opposite ends of the jack and also communicate with the reservoir through a common line 18.
  • Check valves 20 and 21 are provided to prevent flow from lines 16 and 17 to the reservoir but to permit flow from the reservoir to either end of the jack for makeup fluid which prevents cavitation during operation of the jack.
  • valve 14 is illustrated in its H or hold position and it can be seen that in its F or float position, both ends of the jack would be in open communication with each other so that the blade would move freely either upwardly or downwardly in response to external forces.
  • valve 14 With the valve 14 in its hold position, opposite ends of the jack are placed in communication with each other through lines 23 and 24, a manually actuated auxiliary control valve 25 and a pressure relief valve 26. With the valve 25 in its closed position, there is no eflFect upon the conventional circuit previously described. However, with the valve 25 in its open position as shown, upward movement of the blade by external force is permitted with fluid being expelled from the head end of the jack through the line 23, the valve 25 and the line 28 communicating with line 18 while makeup fluid is supplied to the rod end of the jack through the check valve 21 and line 17. Downward movement of the blade is permitted only by the application of force sufficient to open the spring loaded relief valve 26.
  • the blade is in a semi-float position where it is free to move upwardly with upward movement of the push block which is shown at 32 and to move downwardly with the push block.
  • the blade will not drop to the ground because its gravitational force is insufficient to effect opening of the relief valve 26.
  • a hydraulic control circuit for raising and lowering a bulldozer blade including a double acting hydraulic jack controllably connected to the bulldozer blade, a source of supply of fluid under pressure, and valve means to direct flow of said fluid selectively to opposite ends of the jack, auxiliary conduits forming communication between opposite ends of the jack, an auxiliary valve controlling flow of fluid between the head and rod ends of the jack whereby with the auxiliary valve open the bulldozer blade will tend to float, and a relief valve in said conduits preventing downward floating of the bulldozer blade until a predetermined pressure is realized to open the relief valve.
  • valve means to direct fluid selectively to opposite ends of the jack, said valve means including a hold position preventing flow to or from either end of the jack, and means operable with the valve means in said hold position to permit limited 5 flow from one end of the jack toward the other to establish a semi-float condition of the bulldozer blade.

Description

Oct. 14,1969 E sc m-r 3,472,127
CONTROL CIRCUIT FOR BULLDOZERS USED IN PUSHING Filed Dec. 12, 196'? R E$ERVQK Q INVENTOR JAMES E. SCHEDT -.,Ww, PM; r4
ATToRNEYs United States Patent US. 'Cl. 91-437 5 Claims ABSTRACT OF THE DISCLOSURE A control circuit for bulldozers which are used as pushers of other vehicles and particularly to a circuit which provides a modification of the conventional float arrangement by preventing the bulldozer blade from dropping to the ground when it loses contact momentarily with a push block with which it is engaged.
Hydraulically actuated bulldozers usually have conventional controls including a manually actuated valve with raise and lower positions, a neutral or hold position in which the blade is hydraulically locked in any selected attitude and a float position which interconnects the pump reservoir and operative ends of the bulldozer jack so that the blade is free to float or move upwardly or downwardly in response to gravity or other external forces.
When a bulldozer is used in pushing operations such for example as when it is pushing a scraper to provide extra power required during its loading cycle, the bulldozer blade is brought into engagement with a push block on the rear of the scraper and the valve is adjusted to its hold position. This has disadvantages because as the scraper and tractor move over uneven terrain, the height of the blade varies relative to the push block causing a scrubbing action against the mold board of the blade which results in excessive wear. Another disadvantage is that with the blade locked in its hold position, action between the blade and push block sometimes raises the forward end of the tractor sufliciently to reduce its tractive effort. To overcome these disadvantages, some operators place the blade in its hold position while contacting the push block and then move the control to the float position so that the blade is free to follow the movement of the push block. However, loss of contact with the push block with the blade in float position permits the blade to drop to the ground so that this practice is not satisfactory.
It is an object of the present invention to provide an improved hydraulic circuit for the control of a bulldozer blade with means to effect more eflicient and safe operation during pushing with the blade.
A further object is to provide a circuit including auxiliary valve means to establish a semi-float position of a bulldozer blade in which the blade is free to move up wardly and can be moved downwardly by external forces which exceed the force of gravity normally causing the blade to drop.
Further and more specific objects and advantages of the invention are made apparent in the following specification by reference to the accompanying drawing.
The drawing is a schematic view of a bulldozer blade control circuit embodying the present invention and illustrating the blade in contact with a push block.
A conventional circuit includes a hydraulic jack, generally indicated at 10, for raising and lowering a bulldozer blade 11. Fluid from a reservoir 12 is directed selectively to opposite ends of this jack by a pump 13 and a manually actuated control valve 14 having raise, hold, lower and float positions as above described. A conventional relief valve 15 prevents overloading of the circuit and lines 16 and 17 communicate with opposite ends of the jack and also communicate with the reservoir through a common line 18. Check valves 20 and 21 are provided to prevent flow from lines 16 and 17 to the reservoir but to permit flow from the reservoir to either end of the jack for makeup fluid which prevents cavitation during operation of the jack.
The valve 14 is illustrated in its H or hold position and it can be seen that in its F or float position, both ends of the jack would be in open communication with each other so that the blade would move freely either upwardly or downwardly in response to external forces.
In accordance with the present application, with the valve 14 in its hold position, opposite ends of the jack are placed in communication with each other through lines 23 and 24, a manually actuated auxiliary control valve 25 and a pressure relief valve 26. With the valve 25 in its closed position, there is no eflFect upon the conventional circuit previously described. However, with the valve 25 in its open position as shown, upward movement of the blade by external force is permitted with fluid being expelled from the head end of the jack through the line 23, the valve 25 and the line 28 communicating with line 18 while makeup fluid is supplied to the rod end of the jack through the check valve 21 and line 17. Downward movement of the blade is permitted only by the application of force sufficient to open the spring loaded relief valve 26. Upon downward movement, fluid from the rod end of the jack will flow through line 24, valve 25, relief valve 26 and thence through a line 30 back through the valve 25 toward the head end of the jack with the makeup valve 20 functioning in its usual manner. A setting of relief valve 26 is established which prevents opening of the valve by the force exerted by the weight of the blade and its supporting mechanism.
Consequently with the main control valve 14 in its hold position and the auxiliary valve 25 in its open position, the blade is in a semi-float position where it is free to move upwardly with upward movement of the push block which is shown at 32 and to move downwardly with the push block. However, upon loss of contact between the blade and block, the blade will not drop to the ground because its gravitational force is insufficient to effect opening of the relief valve 26.
I claim:
1. In a hydraulic control circuit for raising and lowering a bulldozer blade including a double acting hydraulic jack controllably connected to the bulldozer blade, a source of supply of fluid under pressure, and valve means to direct flow of said fluid selectively to opposite ends of the jack, auxiliary conduits forming communication between opposite ends of the jack, an auxiliary valve controlling flow of fluid between the head and rod ends of the jack whereby with the auxiliary valve open the bulldozer blade will tend to float, and a relief valve in said conduits preventing downward floating of the bulldozer blade until a predetermined pressure is realized to open the relief valve.
2. The combination of claim 1 in which the pressure required to open the relief valve is greater than that produced by the force of gravity of the bulldozer blade.
3. The combination of claim 1 in which the hydraulic control circuit includes conduits between opposite ends of the jack and the source of supply, an anti-cavitation check valve in said conduits for each end of the jack, and means communicating between said auxiliary conduits through said check valves to the source of supply.
4. In a hydraulic control circuit for raising and lowering a bulldozer blade including a double acting hydraulic jack controllably connected to the bulldozer blade, 9.
3 source of supply of fluid under pressure, valve means to direct fluid selectively to opposite ends of the jack, said valve means including a hold position preventing flow to or from either end of the jack, and means operable with the valve means in said hold position to permit limited 5 flow from one end of the jack toward the other to establish a semi-float condition of the bulldozer blade.
5. The combination of claim 4 with auxiliary valve means to prevent such limited flow.
4 References Cited UNITED STATES PATENTS 2,543,989 3/1951 Rockwell 91--437 X 3,032,994 5/1962 Lindell.
EDGAR W. GEOGHEGAN, Primary Examiner US. Cl. X.R. 6052
US689924A 1967-12-12 1967-12-12 Control circuit for bulldozers used in pushing Expired - Lifetime US3472127A (en)

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Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3630121A (en) * 1968-11-29 1971-12-28 Akermans Verkstad Ab Excavating machines
US3788401A (en) * 1972-07-17 1974-01-29 Caterpillar Tractor Co Hydraulic circuit with valve to provide semi-float control of a dozer blade
US4034815A (en) * 1975-03-20 1977-07-12 Caterpillar Tractor Co. Blade lift float circuit for motor graders
US4314502A (en) * 1979-01-15 1982-02-09 Isi Fluid Power, Inc. Safety control system for double-acting cylinder
US4359931A (en) * 1981-01-19 1982-11-23 The Warner & Swasey Company Regenerative and anticavitation hydraulic system for an excavator
US4393943A (en) * 1978-02-21 1983-07-19 Stiftelsen Industriellt Utvecklingscentrum Telescoping carrier for forestry equipment
DE3245288A1 (en) * 1982-12-03 1984-06-14 O & K Orenstein & Koppel Ag, 1000 Berlin METHOD FOR SAVING ENERGY WHEN SETTING AN EQUIPMENT CYLINDER ON A HYDRAULIC EXCAVATOR BY A HYDRAULIC CIRCUIT
EP0389136A1 (en) * 1989-03-08 1990-09-26 Kabushiki Kaisha Kobe Seiko Sho Float circuit for boom of construction apparatus
EP0436740A1 (en) * 1989-08-02 1991-07-17 Kabushiki Kaisha Komatsu Seisakusho Linear excavation control apparatus in hydraulic excavator
US5044256A (en) * 1990-11-05 1991-09-03 Caterpillar Inc. Exhaust pressurizing control for a fluid system
US5284083A (en) * 1991-11-26 1994-02-08 Messier-Bugatti System for powering the driving actuator of an aircraft undercarriage
US20040221714A1 (en) * 2003-02-21 2004-11-11 Marcus Bitter Hydraulic control circuit for a hydraulic lifting cylinder
US20070056280A1 (en) * 2005-09-13 2007-03-15 Marcus Bitter Loading implement and process for loading implement
US20110011257A1 (en) * 2009-07-16 2011-01-20 Parker Hannifin Corporation Electro-hydraulic actuator having end cap with split bushing
WO2013095926A1 (en) * 2011-12-23 2013-06-27 Caterpillar Inc. Hydraulic system for controlling a work implement
ITUB20159831A1 (en) * 2015-12-14 2017-06-14 Ghim Hydraulics S R L HYDRAULIC DEVICE PARTICULARLY SUITABLE FOR THE MOVEMENT OF A SNOW BLADE
US9708796B2 (en) 2014-09-25 2017-07-18 Cnh Industrial America Llc Hydraulic valve
US9790964B2 (en) 2014-09-25 2017-10-17 Cnh Industrial America Llc Hydraulic system
US11280059B2 (en) * 2017-03-24 2022-03-22 Hitachi Construction Machinery Tierra Co., Ltd. Hydraulic drive system for construction machine

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543989A (en) * 1945-02-28 1951-03-06 Plant Choate Mfg Co Inc Hydraulic system for operating hydraulic cylinders and pistons
US3032994A (en) * 1959-12-14 1962-05-08 Koehring Co Hydraulic drive for trenching machine

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543989A (en) * 1945-02-28 1951-03-06 Plant Choate Mfg Co Inc Hydraulic system for operating hydraulic cylinders and pistons
US3032994A (en) * 1959-12-14 1962-05-08 Koehring Co Hydraulic drive for trenching machine

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3630121A (en) * 1968-11-29 1971-12-28 Akermans Verkstad Ab Excavating machines
US3788401A (en) * 1972-07-17 1974-01-29 Caterpillar Tractor Co Hydraulic circuit with valve to provide semi-float control of a dozer blade
US4034815A (en) * 1975-03-20 1977-07-12 Caterpillar Tractor Co. Blade lift float circuit for motor graders
US4393943A (en) * 1978-02-21 1983-07-19 Stiftelsen Industriellt Utvecklingscentrum Telescoping carrier for forestry equipment
US4314502A (en) * 1979-01-15 1982-02-09 Isi Fluid Power, Inc. Safety control system for double-acting cylinder
US4359931A (en) * 1981-01-19 1982-11-23 The Warner & Swasey Company Regenerative and anticavitation hydraulic system for an excavator
DE3245288A1 (en) * 1982-12-03 1984-06-14 O & K Orenstein & Koppel Ag, 1000 Berlin METHOD FOR SAVING ENERGY WHEN SETTING AN EQUIPMENT CYLINDER ON A HYDRAULIC EXCAVATOR BY A HYDRAULIC CIRCUIT
EP0389136A1 (en) * 1989-03-08 1990-09-26 Kabushiki Kaisha Kobe Seiko Sho Float circuit for boom of construction apparatus
EP0436740A1 (en) * 1989-08-02 1991-07-17 Kabushiki Kaisha Komatsu Seisakusho Linear excavation control apparatus in hydraulic excavator
EP0436740A4 (en) * 1989-08-02 1991-09-11 Kabushiki Kaisha Komatsu Seisakusho Linear excavation control apparatus in hydraulic excavator
US5598648A (en) * 1989-08-02 1997-02-04 Kabushiki Kaisha Komatsu Seisakusho Apparatus for controlling straight excavating operation with hydraulic excavator
US5044256A (en) * 1990-11-05 1991-09-03 Caterpillar Inc. Exhaust pressurizing control for a fluid system
EP0565645A1 (en) * 1990-11-05 1993-10-20 Caterpillar Inc Exhaust pressurizing control for a fluid system.
EP0565645A4 (en) * 1990-11-05 1994-04-13 Caterpillar Inc.
US5284083A (en) * 1991-11-26 1994-02-08 Messier-Bugatti System for powering the driving actuator of an aircraft undercarriage
US20040221714A1 (en) * 2003-02-21 2004-11-11 Marcus Bitter Hydraulic control circuit for a hydraulic lifting cylinder
US7104181B2 (en) * 2003-02-21 2006-09-12 Deere & Company Hydraulic control circuit for a hydraulic lifting cylinder
US20070056280A1 (en) * 2005-09-13 2007-03-15 Marcus Bitter Loading implement and process for loading implement
US7430953B2 (en) * 2005-09-13 2008-10-07 Deere & Company Loading implement and process for loading implement
US20110011257A1 (en) * 2009-07-16 2011-01-20 Parker Hannifin Corporation Electro-hydraulic actuator having end cap with split bushing
WO2013095926A1 (en) * 2011-12-23 2013-06-27 Caterpillar Inc. Hydraulic system for controlling a work implement
US9085873B2 (en) 2011-12-23 2015-07-21 Caterpillar Inc. Hydraulic system for controlling a work implement
US9708796B2 (en) 2014-09-25 2017-07-18 Cnh Industrial America Llc Hydraulic valve
US9790964B2 (en) 2014-09-25 2017-10-17 Cnh Industrial America Llc Hydraulic system
ITUB20159831A1 (en) * 2015-12-14 2017-06-14 Ghim Hydraulics S R L HYDRAULIC DEVICE PARTICULARLY SUITABLE FOR THE MOVEMENT OF A SNOW BLADE
US11280059B2 (en) * 2017-03-24 2022-03-22 Hitachi Construction Machinery Tierra Co., Ltd. Hydraulic drive system for construction machine

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