US3443380A - Two-pump system for lift cylinder - Google Patents

Two-pump system for lift cylinder Download PDF

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Publication number
US3443380A
US3443380A US694921A US3443380DA US3443380A US 3443380 A US3443380 A US 3443380A US 694921 A US694921 A US 694921A US 3443380D A US3443380D A US 3443380DA US 3443380 A US3443380 A US 3443380A
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US
United States
Prior art keywords
pump
lift
valve
primary
ram
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.)
Expired - Lifetime
Application number
US694921A
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English (en)
Inventor
Arvin Karazija
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Allis Chalmers Corp
Original Assignee
Allis Chalmers Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
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Publication of US3443380A publication Critical patent/US3443380A/en
Assigned to WOODS KATHLEEN D., AS TRUSTEE, CONNECTICUT NATIONAL BANK THE, A NATIONAL BANKING ASSOCIATION AS TRUSTEE reassignment WOODS KATHLEEN D., AS TRUSTEE SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ALLIS-CHALMERS CORPORATION A DE CORP.
Anticipated expiration legal-status Critical
Assigned to FIRST NATIONAL BANK OF CHICAGO, THE reassignment FIRST NATIONAL BANK OF CHICAGO, THE SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AC MATERIAL HANDLING CORPORATION, AN OH CORP
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S60/00—Power plants
    • Y10S60/911—Fluid motor system incorporating electrical system

Definitions

  • a lift ram is supplied fluid by a primary circuit having a control valve and by a secondary circuit connected directly to the lift ram through one-way valve means.
  • a load check valve is employed in the primary circuit upstream of the control valve and the secondary circuit is connected to the primary circuit upstream of the load check valve by a bypass passage with check valve permitting flow from the secondary passage to the relief valve for the primary pump located upstream of the load check valve in the primary circuit. The need of a separate relief valve for the fluid pump of the secondary circuit is thus obviated.
  • This invention relates to a hydraulic control system for a lift truck utilizing two pumps, the delivery of one of which is controlled by a control valve and the delivery of the other of Which is connected directly to the ram through a one-way valve.
  • the present invention is schematically illustrated in a control system for a lift ram 11, the rod 12 of which carries a pulley 13 having a lift chain 14 reeved thereabout and connected at its opposite ends to the cylinder 16 of the ram 11 and to a carriage 17.
  • the lower end of the ram 11 is pivotally connected to a lift truck chassis 18 and pivoting of the ram 11 about such pivot connection is controlled by a double acting hydraulic jack 19 having its opposite ends pivotally connected to the lift truck chassis 18 and the ram 11.
  • Hydraulic fluid is supplied to the lower end of the lift ram 11 by a primary pump 21 connected in driven relation to primary electric motor 22.
  • One end of the primary control circuit is connected to an hydraulic reservoir 27 and the other end is connected through control valve 24 with the bottom end of the lift ram 11.
  • Increased lift speed may be selected by the operator by supplying additional fluid to the ram 11 through a secondary circuit 36 which includes a secondary pump 37 driven by a secondary electric motor 38.
  • One end of the secondary circuit is connected to reservoir 27 and the other end is connected to primary circuit 23 in fluid delivery relation to the lift ram 11.
  • a one-way valve in the for-m of a ball check valve 39 I is provided in the secondary circuit 36 permitting fluid flow from the secondary pump to the lift ram 11 but preventing a reverse flow so that the operator may employ only the primary pump 21 to raise the lift ram if he so desires.
  • the control valve 24 will, of course, permit fine adjustment and control of the carriage raising speed.
  • the output of the primary pump 21 is relieved to its input side through a bypass passage 41 in which relief valve 42 is placed.
  • the bypass passage 41 is connected to the primary circuit 23 in upstream relation to the load check valve 34 and is connected to reservoir 27 through return line 30.
  • the secondary circuit 36 is connected to the primary circuit 23 at the output side of the pumps 37, 21 by an interconnecting passage 46 containing a check valve 47 which permits fluid flow from the secondary passage to the primary passage upstream of the check valves 39, 34.
  • Check valve 47 prevents flow from the primary passage 23 to the secondary passage 36
  • This interconnecting passage 46 with check valve 47 eliminates the need for a second relief valve for the secondary pump 37 because it permits relief valve 42 to act as the relief valve for the secondary pump 37 as well as the primary pump 21.
  • the illustrated system for controlling the lift ram 11 and tilt jack 19 has particular application in an electric powered lift truck.
  • an electric powered lift truck In such a truck, it has been found economical to use two hydraulic pumps since the combined capacity is only required when the operator desires extra high lift speed.
  • the pumps are selectively operated only when it is desired to deliver pressure fluid to the lift ram or tilt jack. This is achieved by electric motor control means associated with the control valves.
  • control valve 24 When the operator desires to employ the output of primary pump 21 to extend the lift ram 11, the control valve 24 is adjusted downwardly by the control lever 26 from its illustrated hold position 51 to its raise position 52 in which fluid output is delivered through load check valve 34 to the bottom end of the lift ram 11. This is achieved by virtue of electric contacts 61, 62 having been bridged by contactor 63 carried by the control valve 24, thus energizing motor 22 by connecting it to the power source in the form of a storage battery 64.
  • the present invention provides a new and novel control system for a lift ram in which the requirement for a second relief valve for the secondary pump has been obviated. This is accomplished Without eliminating the desirable load check valve 34 from the primary circuit. It should be understood, of course, that when control valve 24 is moved upwardly to its lower position 53, the lower end of the lift ram will be connected to return to reservoir passage 45 and the contactor 66 will not bridge contacts 61, 6-2.
  • a hydraulic control system for a lift ram of the type having primary means for supplying hydraulic pressure fluid to said lift ram, including a primary pump, control valve, load check valve upstream of said control valve and relief valve means for relieving said system intermediate said primary pump and load check valve;
  • secondary means for selectively supplying hydraulic pressure fluid to said lift ram including a secondary pump connected to said lift ram through a check valve, and
  • means for relieving said secondary pump including passage means between the output of said secondary pump and said relief valve means and one-way valve means in said passage means preventing fluid flow therein in the direction toward said secondary pump and permitting fluid flow in the opposite direction when the delivery pressure of said secondary pump exceeds the delivery pressure of said primary pump.
  • the invention of claim 3 including manual control means for controlling delivery of hydraulic pressure fluid to said lift ram by said secondary means.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Forklifts And Lifting Vehicles (AREA)
  • Fluid-Pressure Circuits (AREA)
US694921A 1968-01-02 1968-01-02 Two-pump system for lift cylinder Expired - Lifetime US3443380A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US69492168A 1968-01-02 1968-01-02

Publications (1)

Publication Number Publication Date
US3443380A true US3443380A (en) 1969-05-13

Family

ID=24790805

Family Applications (1)

Application Number Title Priority Date Filing Date
US694921A Expired - Lifetime US3443380A (en) 1968-01-02 1968-01-02 Two-pump system for lift cylinder

Country Status (3)

Country Link
US (1) US3443380A (enrdf_load_stackoverflow)
FR (1) FR1598899A (enrdf_load_stackoverflow)
GB (1) GB1177900A (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3486333A (en) * 1968-03-26 1969-12-30 Clark Equipment Co Upright control system for use in a lift truck
US3630025A (en) * 1970-06-01 1971-12-28 Allis Chalmers Mfg Co Control system for hydraulic devices
US3754394A (en) * 1971-12-02 1973-08-28 Hyster Co Hydraulic control system for electric lift truck
US3785156A (en) * 1971-12-27 1974-01-15 Caterpillar Tractor Co Hydraulic control for self-loading scraper with three-speed elevator drive
US3916624A (en) * 1973-11-14 1975-11-04 Massey Ferguson Services Nv Hydraulic controls
US4012175A (en) * 1975-12-31 1977-03-15 Douglas Dynamics Corporation Valve and pump control for a hydraulic system
US4449365A (en) * 1979-11-19 1984-05-22 Allis-Chalmers Corporation Lift, tilt and steering control for a lift truck
WO1986006142A1 (en) * 1985-04-11 1986-10-23 Caterpillar Industrial Inc. Fluid operated system control
US4665698A (en) * 1983-04-18 1987-05-19 Clark Equipment Company Hydraulic system with proportional control
US5842848A (en) * 1997-01-03 1998-12-01 Knowles; Frederick W. Compact high-volume gear pump
US6293099B1 (en) * 1999-06-28 2001-09-25 Kabushiki Kaisha Toyoda Jidoshokki Seisakusho Hydraulic circuit for forklift
US6369339B1 (en) * 1999-10-18 2002-04-09 Jan Noord Apparatus for manipulating a load
US20110283691A1 (en) * 2010-04-30 2011-11-24 Dybing Philip J Multiple fluid pump combination circuit
US9217447B2 (en) 2011-07-01 2015-12-22 Eaton Corporation Hydraulic systems utilizing combination open- and closed-loop pump systems

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2323519A (en) * 1941-01-24 1943-07-06 Ternstedt Mfg Co Vacuum operated window regulator
US2979908A (en) * 1960-01-04 1961-04-18 Warner Swasey Co Hydraulic control systems
US3154921A (en) * 1962-01-19 1964-11-03 Caterpillar Tractor Co Fluid pressure system and control
US3171247A (en) * 1962-05-24 1965-03-02 Webster Electric Co Inc Motor vehicle and hydraulic system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2323519A (en) * 1941-01-24 1943-07-06 Ternstedt Mfg Co Vacuum operated window regulator
US2979908A (en) * 1960-01-04 1961-04-18 Warner Swasey Co Hydraulic control systems
US3154921A (en) * 1962-01-19 1964-11-03 Caterpillar Tractor Co Fluid pressure system and control
US3171247A (en) * 1962-05-24 1965-03-02 Webster Electric Co Inc Motor vehicle and hydraulic system

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3486333A (en) * 1968-03-26 1969-12-30 Clark Equipment Co Upright control system for use in a lift truck
US3630025A (en) * 1970-06-01 1971-12-28 Allis Chalmers Mfg Co Control system for hydraulic devices
US3754394A (en) * 1971-12-02 1973-08-28 Hyster Co Hydraulic control system for electric lift truck
US3785156A (en) * 1971-12-27 1974-01-15 Caterpillar Tractor Co Hydraulic control for self-loading scraper with three-speed elevator drive
US3916624A (en) * 1973-11-14 1975-11-04 Massey Ferguson Services Nv Hydraulic controls
US4012175A (en) * 1975-12-31 1977-03-15 Douglas Dynamics Corporation Valve and pump control for a hydraulic system
US4449365A (en) * 1979-11-19 1984-05-22 Allis-Chalmers Corporation Lift, tilt and steering control for a lift truck
US4665698A (en) * 1983-04-18 1987-05-19 Clark Equipment Company Hydraulic system with proportional control
US4635439A (en) * 1985-04-11 1987-01-13 Caterpillar Industrial Inc. Fluid operated system control
WO1986006142A1 (en) * 1985-04-11 1986-10-23 Caterpillar Industrial Inc. Fluid operated system control
GB2193012A (en) * 1985-04-11 1988-01-27 Caterpillar Ind Inc Fluid operated system control
US5842848A (en) * 1997-01-03 1998-12-01 Knowles; Frederick W. Compact high-volume gear pump
US6293099B1 (en) * 1999-06-28 2001-09-25 Kabushiki Kaisha Toyoda Jidoshokki Seisakusho Hydraulic circuit for forklift
US6369339B1 (en) * 1999-10-18 2002-04-09 Jan Noord Apparatus for manipulating a load
US20110283691A1 (en) * 2010-04-30 2011-11-24 Dybing Philip J Multiple fluid pump combination circuit
US9574579B2 (en) * 2010-04-30 2017-02-21 Eaton Corporation Multiple fluid pump combination circuit
US9217447B2 (en) 2011-07-01 2015-12-22 Eaton Corporation Hydraulic systems utilizing combination open- and closed-loop pump systems

Also Published As

Publication number Publication date
FR1598899A (enrdf_load_stackoverflow) 1970-07-06
GB1177900A (en) 1970-01-14

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Legal Events

Date Code Title Description
AS Assignment

Owner name: WOODS KATHLEEN D., AS TRUSTEE

Free format text: SECURITY INTEREST;ASSIGNOR:ALLIS-CHALMERS CORPORATION A DE CORP.;REEL/FRAME:004149/0001

Effective date: 19830329

Owner name: CONNECTICUT NATIONAL BANK THE, A NATIONAL BANKING

Free format text: SECURITY INTEREST;ASSIGNOR:ALLIS-CHALMERS CORPORATION A DE CORP.;REEL/FRAME:004149/0001

Effective date: 19830329

AS Assignment

Owner name: FIRST NATIONAL BANK OF CHICAGO, THE

Free format text: SECURITY INTEREST;ASSIGNOR:AC MATERIAL HANDLING CORPORATION, AN OH CORP;REEL/FRAME:004648/0689

Effective date: 19860731