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Publication numberUS3908515 A
Publication typeGrant
Publication dateSep 30, 1975
Filing dateSep 10, 1973
Priority dateSep 10, 1973
Also published asCA1025326A, CA1025326A1
Publication numberUS 3908515 A, US 3908515A, US-A-3908515, US3908515 A, US3908515A
InventorsJohnson Howard L
Original AssigneeCaterpillar Tractor Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Hydraulic circuit with selectively actuatable float control
US 3908515 A
Abstract
A hydraulic system having the combination of a source of pressurized fluid, a linear hydraulic motor, a main control valve to selectively direct hydraulic fluid to the motor, and a lock valve disposed between the control valve and motor is provided with an auxiliary valve to by-pass the main control valve to disable the lock valve to provide a float condition for the motor.
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Description  (OCR text may contain errors)

United States Patent Johnson 1 Sept. 30, 1975 [54] HYDRAULIC CIRCUIT WITH 3.274.902 9/1966 Klcckncr 91/420 SELECTIVELY ACTUATABLE FLOAT 3.381.587 5/1968 Parquet 91/420 CONTROL 3.543.647 12/1970 -Hall et a1. 91/420 3.558 102 1/1971 Cruse 91/447 X [75] Inventor: Howard L. Johnson, Jolict. 111. 3.583.438 6/1971 Ru hs 37/596 3.608.431 9/1971 Pczlse 91/454 X 1 Asslgneel CaterPIllar Tractor y. 3,730207 5 1973 Christensen 91 437 x Peoria, 111.

[22] Filed: Sept 10, 1973 Primary E.\aminerlrwin C. Cohen Attorney, Agent, 0" Firm-Phillips Moore, PP 395.647 Wcissenberger Lempio & Strabala 52 us. Cl. 91/420; 91/437; 91/445; 1 ABSTRACT 91/447; 91/453; 91/464 A hydraulic system having the combination of a [51 1 Int. Cl.'- F1513 11/08; F1513 13/042; source of pressurized fluid, a linear hydraulic motor, a FlSB 13/043 main control valve to selectively direct hydraulic fluid [58] Field of Search 91/420, 445, 437, 447, to the motor, and a lock valve disposed between the.

91/453, 464; 137/596.l2, 596.13 control valve and motor is provided with an auxiliary valve to by-pass the main control valve to disable the [56] References Cited lock valve to provide a float condition for the motor.

UNITED STATES PATENTS 2.517.164 8/1950 Arps 91/420 X' 3 Claims, 2 Drawing Figures f -1T1 'E' IIIJ -25 L .LL

Z4- Z0 +5 Z5 3 0 3 1 28 1'2 BACKGROUND OF THE INVENTION The present invention relates to hydraulic circuits and pertains particularly to a circuit having a lock valve selectively actuatablc to provide a floating-condition for a hydraulicjack.

It is common practice to utilize anearthmoving vehi cle for ancillary operations. by attaching an auxiliary implement thereto. For example, motor graders are'frequently employed for snow removal by attaching a snow plow to the forward end thereof. In many cases, the auxiliary implement, suchtas the snow plow, operates more efficiently if it is free to ride or float on the surface so it can follow the surface contour. However, many of the hydraulic control systems of such vehicles employ a lock valve which would prevent free floating of the blade. Thus, one of the difficulties encountered in using a vehicle for ancillary operations is that of providing an attachment type control circuit which provides a float position-without employing a sophisticated and expensive control valve, and which is compatible with. the basic hydraulic circuit of the vehicle.

SUMMARY OF THE INVENTION A BRIEF-DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will become apparent from the following description when read in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic layout of a Circuit in accordance with the present invention; and

FIG. 2 is a schematic of a modification of an auxiliary valve for the circuit of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring more particularly to FIG. 1 of the drawing, a hydraulic circuit in accordance with the present invention generally comprises a source of pressurized fluid including a pump 11 which draws fluid from a sump or reservoir 12. The pump supplies pressurized fluid by way of a supply conduit 13 to a main control valve 14 with fluid exhausted from the control valve being returned to the reservoir through a return line or conduit 15. A relief valve 16 interconnects the supply conduit 13 and the return conduit to relieve excessive pressure in the hydraulic circuit.

The control valve 14 is of the type that has three positions attainable by actuation of a control lever 17 to one of the three positions indicated by the letters R, N, and L. The control valve is operative in selecting one of the R or L positions to direct fluid via supply lines 21 and 22 to either the head or rod end of a double act- ,ing..hydr aulic motor orjac k 23. when the control valve is in theneutral position, both of a pair of control eonduits 18 and 19 are in communication with the return conduit 15 to: reservoir 12. The conduits l8 and 19 communicate fluid'from the control valve 14 to a pilot operable lock valve 20, where the fluid is communicated by way of motor supply lines 21 and 22 to jack 23. The hydraulic jac k 23is controlled by the lock valve through conduits 21 and 22.

The lock valve 20 includes a valve body'24 having a bore 2 5-extending longitudinally therethrough. A first pair of axially'spa ced radial ports 26 and 27 are formed in. the body and. communicate the conduits l8 and 19, respectively, with the bore 25. A second pair of axially spaced radial ports 28 and 29 are formed in the body and communicate the conduits 21 and 22, respectively, with the bore. The valve body has a third radial port 30 formed therein intermediate the ports 26 and 27.

' A pair of identical check valve assemblies 31 and 32 are individually disposed in opposite ends of the bore and secured in place by a respective one of a pair of plugs 33 and 34 individually threadably secured in the open end of the bore. Check valve assembly 31 normally blocks port 2 8 from port 26 while check valve assembly 32 normally blocks port 29 from port 27. Each check valve assembly includes a ball 35 and 36 resiliently urged against a seat 37 and 38 by a compression .check valve assembly.

A pair of solenoid control valves 48 and 4) are in communicationwith the port 30 and Chamber 45v of the valve body through a conduit 50. The valve 48 is normally open and in communication with reservoir 12 through a return conduit 51. The solenoid valve 49 is normally closed and communicates with the lluid supply conduit 13 through a branch or by-pass conduit 52. A suitable conductor 53 electically connects the solenoid valves to a normally open toggle switch 54 which is connected to a suitable electrical source such as a battery 55.

In an alternate embodiment as shown in FIG. 2, the solenoid operated valves 48 and 49 of FIG. 1 may be replaced with a single 2-position, 3-way solenoid control valve 56 which normally communicates the conduit 50 with the return conduit 51. (losing the toggle switch 54 energizes the solenoid control valve causing it to shift to a position to communicate the branch conduit 52 with the conduit 50. This communicates pressufrized fluid to chamber 45 which forces pistons 41 and 42 to unseat ball check valves 35 and 36 to thereby disable the lock valve 20. i

OPERATION During normal vehicular operation, the toggle switch 54 is open so that the chamber 45 is vented to the reservoir 12 through the conduit 50, the normally open solenoid valve 48, and the return conduit 51. With ehanv ber 45 vented, the lock valve 20 functions as a Conventional lock valve whereby fluid from both ends of the hydrostatic jack 23 is blocked by the respective check valve assemblies 31 and 32 of the lock valve. When the control valve 14 is shifted to direct pressurized fluid through conduit 18 to the lock valve, the ball 35 of the check valve assembly 31 is unseated by the pressurized fluid which is then transmitted to the hydraulic jack through conduit 21. Simultaneously, the pressurized fluid entering the lock valve through the conduit 18 acts upon the actuator piston 41 shifting it and the actuator piston 42 to the right. The plunger 47 of the piston 42 engages and unseats the ball 36 of the check valve assembly 32 permitting fluid exhausted from the hydraulic jack through the conduit 22 to be exhausted through conduit 19, the control valve 14 and the return conduit to the reservoir 12. Conversely, pressurized fluid directed through conduit 19 passes through the lock valve in a similar manner and to the head end of the hydraulic jack through conduit 22. The fluid exhausted through conduit 21 passes through the lock valve 20, conduit 18, control valve 14, and return conduit 15 to the reservoir. 1

To obtain a float position of the hydraulic jack 23, the toggle switch 54 is closed to direct electrical energy to the solenoid control valves 48 and 49. Simultaneously, the valve 48 is shifted to a closed position blocking communication therethrough while valve 49 is shifted to an open position to direct pressurized fluid from the pump 11 through conduits 13, 52 and 50 into the chamber 45 of the lock valve 20. The pressurized fluid in chamber 45 urges the actuator pistons 41 and 42 in opposite directions to unseat the balls 35 and 36 of both check valve assemblies 31 and 32. This communicates both the head end and the rod end of the hydraulic jack 23 with the reservoir 12 through the various conduits and provides the float condition.

What is claimed is:

1. In a hydraulic system for selectively positioning a work member in selected fixed positions the combination comprising:

a linear double-acting hydraulic motor connected to a work member, a source of fluid pressure including a sump and a pump for supplying fluid for operating said motor, a three position directional control valve in a valve housing and having a neutral position, and raise and lower positions for selectively directing fluid from said source to either end of said motor for operation of said motor for positioning said work member, a single control lever for operating said control valve, lock valve means including first and second passage means communicating said fluid respectively with alternate ends of said motor, check valve means disposed in each said passage means to normally block flow of said fluid from said motor and including pressure-responsive piston and plunger means in each said passage means for unseating said check valve means to provide communication between both ends of said motor and sump by way of said directional control valve, said check valve means disposed between said control valve means and said hydraulic motor for normally locking said motor in a selected position; solenoid operated auxiliary valve means separate spaced from and independent of said directional control valve and valve housing disposed between said source of fluid pressure and said lock valve means for bypassing said directional control valve for directing fluid solely to each said piston and plunger means solely for unseating each said check valve means for communicating both ends of said motor with said sump by way of said directional control valve for enabling free floating movement of said hydraulic motor when said main control valve is in a neutral position between said raise and said lower positions. 2. The hydraulic system of claim 1 wherein said solenoid operated auxiliary valve means comprises a pair of solenoid operated two-position valves.

3. The hydraulic system of claim 2 including control means for said solenoid operated auxiliary valve means comprising a source of electrical power and switch means for selectively activating said solenoids.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2517164 *Feb 19, 1947Aug 1, 1950Bruno F ArpsTwo-speed hydraulic ram
US3274902 *Oct 22, 1965Sep 27, 1966Deere & CoHydraulic control system
US3381587 *Sep 10, 1965May 7, 1968Deere & CoHydraulic control system
US3543647 *May 2, 1969Dec 1, 1970Deere & CoControl valve means for a two-way hydraulic cylinder
US3558102 *Jan 10, 1969Jan 26, 1971Cruse William MTheater stage set control system
US3583438 *Aug 15, 1969Jun 8, 1971Herion Werke Dg FaSafety arrangements in servo operated systems
US3608431 *Jul 14, 1969Sep 28, 1971Lummus IndustriesControl system for the ram of vertically disposed fluid pressure cylinders
US3730207 *Oct 4, 1971May 1, 1973Danfoss AsValve arrangement for hydraulic steering systems
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4018350 *Mar 17, 1975Apr 19, 1977Pettibone CorporationHydraulic cyliner systems with safeguarded float action
US4039085 *Jun 10, 1976Aug 2, 1977Koehring CompanyCrane with a pivoted boom and a float valve therefor
US4128047 *Jul 14, 1977Dec 5, 1978Textron Inc.Actuator with locking valves
US4130049 *Apr 7, 1977Dec 19, 1978Caterpillar Tractor Co.Vent control for cylinder mounted load check valves
US4165675 *Apr 7, 1977Aug 28, 1979Caterpillar Tractor Co.Load check valve cylinder mounted
US4167892 *Apr 7, 1977Sep 18, 1979Caterpillar Tractor Co.Load check with mechanical venting means
US4170246 *May 23, 1977Oct 9, 1979Sta-Rite Industries, Inc.Pilot operator valve
US4170279 *Apr 13, 1977Oct 9, 1979Societe Anonyme Potain Pioclain Materiel (P.P.M.)Fluid flow control devices
US4286432 *Aug 30, 1979Sep 1, 1981Caterpillar Tractor Co.Lock valve with variable length piston and hydraulic system for a work implement using the same
US4367673 *Jan 9, 1981Jan 11, 1983Dresser Industries, Inc.System and method for controlling the elevation of a boom hoist device
US4417502 *Nov 17, 1980Nov 29, 1983Dresser Industries, Inc.Load supporting hydraulic circuit with emergency automatic load restraint
US4523513 *Jun 27, 1983Jun 18, 1985Wabco Westinghouse Fahrzeugbremsen GmbhPneumatic door-operating arrangement
US4558630 *May 28, 1981Dec 17, 1985Oy Tampella AbHydraulic mechanism with elastically backed piston parts and cooperating valve means
US4619187 *Oct 25, 1982Oct 28, 1986Caterpillar Inc.Fluid control for two independent actuators
US4754693 *Mar 30, 1987Jul 5, 1988Concordia Fluidtechnik GmbhValve
US4761953 *Dec 24, 1986Aug 9, 1988Dynamic Hydraulic Systems, Inc.Hydraulic elevator mechanism
US4761954 *Mar 16, 1987Aug 9, 1988Dynamic Hydraulic Systems, Inc.Fork-lift system
US4768420 *Apr 3, 1987Sep 6, 1988Ernst KorthausControl arrangement for controlling a hydraulic drive for driving a piston pump
US4852660 *Oct 28, 1988Aug 1, 1989O & K Orenstein & Koppel AktiengesellschaftGrader blade having a pressurized float position
US5036750 *Jun 7, 1990Aug 6, 1991Nippon Air Brake Kabushiki KaishaPilot-operated dual check valve assembly with cross-line flow valving pilot pistons
US5235896 *Mar 18, 1992Aug 17, 1993Hoerbiger Fluidtechnik GmbhHydraulic cylinder/piston mechanism
US5284083 *Nov 20, 1992Feb 8, 1994Messier-BugattiSystem for powering the driving actuator of an aircraft undercarriage
US5934176 *Jul 30, 1997Aug 10, 1999Applied Power Inc.Hydraulic operating system
US5988028 *Jul 7, 1997Nov 23, 1999Putzmeister AktiengesellschaftProcess for conveying thick matter containing preshredded scrap metal or similar solids
US6131610 *Nov 19, 1997Oct 17, 2000Smc Kabushiki KaishaSpeed controller with pilot check valve
US6158313 *Oct 8, 1999Dec 12, 2000Putzmeister AktiengesellschaftProcess for conveying thick matter containing preshredded scrap metal or similar solids
US6293180Jul 21, 2000Sep 25, 2001Smc Kabushiki KaishaSpeed controller with pilot check valve
US6293181Sep 21, 1999Sep 25, 2001Caterpillar Inc.Control system providing a float condition for a hydraulic cylinder
US6296015Jun 8, 2000Oct 2, 2001Smc Kabushiki KaishaSpeed controller with pilot check valve
US6997210 *Jul 19, 2002Feb 14, 2006Aladdin Engineering & Manufacturing, Inc.Valve arrangement including release valve
US7472638 *Oct 14, 2005Jan 6, 2009Caterpillar Inc.Hydraulic system with an actuator having independent meter-in meter-out control
US7954420Jul 9, 2008Jun 7, 2011Sauer-Danfoss ApsHydraulic valve arrangement
US8001882 *Sep 10, 2008Aug 23, 2011Volvo Construction Equipment Holding Sweden AbDouble check valve having floating function
US9068322 *May 18, 2010Jun 30, 2015Volvo Construction Equipment AbDouble check valve for construction equipment
US9429174 *Mar 17, 2014Aug 30, 2016Clark Equipment CompanyEnabling valve having separate float and lift down positions
US20030111117 *Jul 19, 2002Jun 19, 2003Horn Edward R.Valve arrangement including release valve
US20060027092 *Oct 14, 2005Feb 9, 2006Caterpillar Inc.Hydraulic system with an actuator having independent meter-in meter-out control
US20080121101 *Jul 6, 2007May 29, 2008Volvo Construction Equipment Holding Sweden AbDouble check valve having floating function
US20090014074 *Jul 9, 2008Jan 15, 2009Sauer-Danfoss ApsHydraulic valve arrangement
US20090078111 *Sep 10, 2008Mar 26, 2009Volvo Construction Equipment Holding Sweden Ab.Double check valve having floating function
US20100218746 *Jul 3, 2009Sep 2, 2010Vianney RabhiBall-lift electrohydraulic valve for a hydraulic power unit of a variable compression ratio engine
US20130055886 *May 18, 2010Mar 7, 2013Volvo Construction Equipment AbDouble check valve for construction equipment
CN102135196A *Jan 26, 2011Jul 27, 2011马克阀门公司Proportional pressure controller
CN102135196BJan 26, 2011Oct 29, 2014马克阀门公司比例压力控制器
DE19919014A1 *Apr 27, 1999Nov 9, 2000Danfoss Fluid Power AsHydraulic valve with locking and floating function has housing bore, in which switch channel optionally providable with pressure and with connecting channels on both sides is connectable by control valve with pressure source and tank
DE19919014C2 *Apr 27, 1999Mar 1, 2001Danfoss Fluid Power As NordborHydraulikventil mit einer Verriegelungs- und einer Schwimmfunktion
DE102007032415B3 *Jul 12, 2007Apr 2, 2009Sauer-Danfoss ApsHydraulische Ventilanordnung
EP0025107A1 *Jul 29, 1980Mar 18, 1981Caterpillar Tractor Co.Lock valve with variable length piston and hydraulic system for a work implement using the same
EP1310680A3 *Nov 5, 2002Aug 10, 2005Botschafter-Knopff, IIseStop valve arrangement and control valve with such a stop valve arrangement
EP1927759A1 *Jul 27, 2007Jun 4, 2008Volvo Construction Equipment Holding Sweden ABDouble check valve having floating function
EP2048372A2 *Sep 16, 2008Apr 15, 2009Volvo Construction Equipment Holding Sweden ABDouble check valve having floating function
EP2048372A3 *Sep 16, 2008May 30, 2012Volvo Construction Equipment Holding Sweden ABDouble check valve having floating function
WO1981000600A1 *Aug 30, 1979Mar 5, 1981Caterpillar Tractor CoLock valve with variable length piston and hydraulic system for a work implement using the same
WO1991019108A1 *May 4, 1991Dec 12, 1991Robert Bosch GmbhPiston-cylinder control device
WO1993013319A1 *Oct 25, 1982Jul 8, 1993Blake William WFluid control for two independent actuators
WO2012082355A2 *Nov 29, 2011Jun 21, 2012Caterpillar Inc.Hydraulic system having load lock valve
WO2012082355A3 *Nov 29, 2011Sep 7, 2012Caterpillar Inc.Hydraulic system having load lock valve
Classifications
U.S. Classification91/420, 91/437, 91/447, 91/445, 91/464, 91/453
International ClassificationF15B13/10, F15B13/01, F15B13/00
Cooperative ClassificationF15B13/01
European ClassificationF15B13/01
Legal Events
DateCodeEventDescription
Jun 12, 1986ASAssignment
Owner name: CATERPILLAR INC., 100 N.E. ADAMS STREET, PEORIA, I
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905
Effective date: 19860515
Owner name: CATERPILLAR INC., A CORP. OF DE.,ILLINOIS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905