US3464320A - Decompression system for press brakes or the like - Google Patents

Decompression system for press brakes or the like Download PDF

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Publication number
US3464320A
US3464320A US638986A US3464320DA US3464320A US 3464320 A US3464320 A US 3464320A US 638986 A US638986 A US 638986A US 3464320D A US3464320D A US 3464320DA US 3464320 A US3464320 A US 3464320A
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United States
Prior art keywords
valve
hydraulic
pump
pressure
passageway
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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
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US638986A
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English (en)
Inventor
Rolland A Richardson
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.)
Pacific Press and Shear Corp
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Pacific Press and Shear Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • B30B15/24—Control arrangements for fluid-driven presses controlling the movement of a plurality of actuating members to maintain parallel movement of the platen or press beam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • B30B15/18—Control arrangements for fluid-driven presses controlling the reciprocating motion of the ram
    • B30B15/186—Controlling the return movement of the ram, e.g. decompression 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/044—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out"
    • 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
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20538—Type of pump constant capacity
    • 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
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/3059—Assemblies of multiple valves having multiple valves for multiple output members
    • 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
    • F15B2211/505—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
    • F15B2211/50536—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid to 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
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a directional control valve
    • 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
    • F15B2211/52—Pressure control characterised by the type of actuation
    • F15B2211/528—Pressure control characterised by the type of actuation actuated by fluid pressure
    • 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
    • F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
    • 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
    • F15B2211/575—Pilot pressure control
    • 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/615—Filtering means
    • 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
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • 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
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders

Definitions

  • the invention relates to hydraulic press brakes or the like, and more particularly, to the hydraulic drive system for such machines, and will be described in connection with the operation of a hydraulic press brake.
  • the ram In the use of a press brake for rubber pad forming, the ram must penetrate and compress a heavy rubber pad during the forming operation. On the return stroke, the spring back of the rubber can mechanically drive the ram back at a rate faster than normal, and this is particularly likely if the load is off center, as this can cause one end of the ram to initiate a faster return than the other, thus unbalancing or cocking the ram and bringing about an unstable return. This situation can develope also when operating on springy steels.
  • FIGURE 1 is a schematic view of a hydraulic system for a press brake or the like, incorporating the features of the present invention
  • FIGURE 2 is a view in section through a valve assembly constituting an important feature of the present invention.
  • FIGURE 3 is a view in section taken in the plane 3-3 of FIGURE 2.
  • These drive motors are supplied with liquid from a pair 3,464,320 Patented Sept. 2, 1969 of pumps 11 and 13, which in turn, draw liquid from a tank 15, each pump having a discharge line 17, 19 respectively, with a flow connection in the form of a branch line 20, to the upper end of one of the hydraulic motor cylinders 7, and another branch line 21 to the lower end of the other motor cylinder.
  • one branch line 20 extends to the drive side of one piston, while the other branch line 21 extends to the lift side of the other piston.
  • Selectively operable valve means in the form of a solenoid controlled valve 27 in one branch line, and a solenoid control valve 29 in the other branch line, from each pump will cause each pump to supply power to one hydraulic motor for a work stroke and power to the other hydraulic motor for a return or lift stroke.
  • This has the advantage over a system where each pump supplies the power for both the work stroke and the lift stroke, to the same hydraulic motor, for such system necessitates a reversing of the hydraulic lines to each hydraulic motor when changing from a work stroke to a lift stroke, which in turn requires a corresponding reversal of lines in a levelling system, if incorporated in such system.
  • a normally closed valve 33 under control of a normally closed solenoid pilot valve 35, is connected in each line 20, while a similar valve 37 under control of a normally open solenoid pilot valve 39 is connected from the line 21 to tank.
  • This valve 37 is normally adjusted to open in response to hydraulic pressure above that necessary to support the ram in its idle position, and with the valve 33 open, will permit a work stroke of the ram.
  • Energization of the pilot valve 39 permits of a faster work stroke.
  • a normally closed valve 41 controlled by a normally closed solenoid pilot valve 43 is connected in each line 21, while a similar valve 45 controlled by a normally open solenoid pilot valve 47, is connected from each line 20 to tank.
  • a relief valve assembly 48 in shunt to each pump, functions in response to an overload on the pump, to connect the overloaded pump to tank, and thus by-pass the overload and protect the pump.
  • each pump discharge line is a blocking valve assembly 50, which is so designed as to normally open in accordance with the work load on the pump which is feeding liquid therethrough.
  • the resistance to opening of such valve may be controlled in part by a flow connection from the discharge line of the other pump, at a point down stream of the blocking valve in that line, whereby the flow connection will transmit the load pressure from the one discharge line to the control element in the blocking valve in the other discharge line.
  • each blocking valve will respond to the load condition at the far end of the ram, to so adjust the loading on its associated pump as to maintain substantially equal loading on the pumps, despite any unbalancing of the work load on the hydraulic motors.
  • valve 45 and pilot valve 47 become part of a modified valve assembly 51 which remains part of the stroke reversing means controlling each hydraulic motor.
  • valve assembly may include a valve housing 55 having an offset main flow passageway therethrough, the input end 57 for flow connection to a pump discharge line 20, while the discharge end 59 is connected to tank 15.
  • a valve seat 61 against which a spool shaped main valve 63 is normally seated by a biasing spring 65 housed in a recess 67 in the valve and bearing against a head section 69 to create a small chamber 71, adjacent that end of the valve.
  • a small opening 73 through the wall of the recess permits liquid communication with the inlet 57 of the main passageway, whereby hydraulic pressure may accumulate in the spring recess and the small chamber above to assist the spring in maintaining closing pressure on the main valve.
  • An auxiliary passageway 77 from the input end of the main flow passageway to the opposite end of the spool shaped main valve, will bring pump pressure to bear against this end of the valve in opposition to the pressure build-up in the spring recess due to the combined liquid pressure and that of the main valve biasing spring.
  • the normal differential pressure will be in the direction of seating the main valve. Any release of the hydraulic pressure assisting the spring will reverse the differential pressure on the main valve, Which will then be in the direction of opening such valve.
  • valve 79 of the pilot valve assembly 47 Slidably mounted on the head section is the valve 79 of the pilot valve assembly 47. Release of hydraulic pressure from the chamber 71 is normally provided by this solenoid actuated valve assembly 47, which is adapted to open or close a by-pass passageway 81 about the main valve, from the chamber, such by-pass passageway including the opening 73, chamber 71, the solenoid valve 79, and a return passageway in the main valve housing 55 which terminates at the discharge end 59 of the main valve passageway.
  • this by-pass passageway passes from the chamber 71 through the head section 69 and the pilot valve, then back through the head section and main valve casing to the outlet end of the main valve passageway.
  • This head section is provided with a longitudinal bore 87 intercepting the bypass passageway.
  • a monitoring valve assembly for adjustably interrupting the by-pass passageway, whereby to independently control flow through the by-pass passageway, when the solenoid controlled valve is in its depicted position to complete the by-pass passageway.
  • the monitoring valve assembly includes a valve sleeve 91 installed at one end of the bore with its exposed end recessed to receive a tube fitting 93. At spaced longitudinal points, the sleeve has passages 95, 97 diametrically therethrough, each connecting with an annular chamber 99, 101 respectively about the sleeve, both annular chambers being thus flow connected by way of the diametrical passages and the longitudinal passageway of the sleeve.
  • One of these diametrical passages 97 is adapted to be blocked off by a spool valve 103, normally biased to its blocking position by a biasing spring 105.
  • the monitor spool valve tapers at its free end to a stem of smaller diameter than the sleeve passageway, and terminates beyond the remaining diametrical passage 95 in a piston 109 slidably fitting the sleeve passage and of a length to abut the inner end of the tube fitting 93. Any pressure exerted through the tube fitting against the piston, if of suflicient magnitude to overcome the pressure of the biasing spring 105, will cause the monitor valve to shift to a position where it will adjustably unblock the diametrical passage 97 in varying degrees in accordance with the pressure applied against the piston.
  • a flow connection 111 to the tube fitting end of the I monitor valve assembly, from the lower end of the cylinder 7, whose discharge, the main valve 63 is to control, will place the monitor valve in pressure sensing relationship to the instantaneous pressure prevailing in the lower portion of the cylinder during a return stroke.
  • a hydraulic press brake or the like comprising a ram having a substantial horizontal dimension, a hydraulic system for driving said ram, said hydraulic system including a plurality of spaced apart hydraulic motors, each including a cylinder and associated piston therein coupled to said ram, pump means, a flow connection from the pressure side of said pump means to the upper end of each of said cylinders with a flow connection from the lower end of each of said cylinders to the intake side of said pump means, whereby liquid will enter the cylinders at their upper ends and discharge from their lower ends to produce a work stroke of said ram, means for reversing the flow to said cylinders to cause liquid to enter the lower ends thereof and discharge from their upper ends to produce a return stroke of said ram, said flow reversing means including a valve assembly for each of said hydraulic motors, and means, during a return stroke of each piston, for variably throttling discharge flow from its associated cylinder through its associated valve assembly when return movement of a piston exceeds that producible by normal pump feed of liquid to its
  • each said throttling means being responsive to a deficiency of liquid pressure on the intake side of a particular piston.
  • each said valve assembly having a main flow passageway included in a flow connection from a cylinder upper end to the intake side of a pump means, a main valve in said passageway and adapted in its seating position, to close said main passageway, means normally seating said valve, and means for unseating said main valve to initiate a return stroke.
  • each of said main valve unseating means as including a pilot valve in pressure relieving relationship to the main valve.
  • each of said throttling means as including a monitoring valve intercepting the pressure relieving relationship between said pilot valve and said 10 References Cited UNITED STATES PATENTS Ernst 91-420 Lankovski et al. 91-420X Deardorff et a1 91-420X Richey 91-420 Thomas 91-420 Olson et al. 91-420 Westveer 91-420 Richardson 91-171 Parquet 91-420 EDWARD G. FAVORS, Primary Examiner

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control Of Presses (AREA)
  • Braking Arrangements (AREA)
US638986A 1967-05-16 1967-05-16 Decompression system for press brakes or the like Expired - Lifetime US3464320A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US63898667A 1967-05-16 1967-05-16

Publications (1)

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US3464320A true US3464320A (en) 1969-09-02

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US638986A Expired - Lifetime US3464320A (en) 1967-05-16 1967-05-16 Decompression system for press brakes or the like

Country Status (4)

Country Link
US (1) US3464320A (pl)
BE (1) BE708654A (pl)
FR (1) FR1548216A (pl)
GB (1) GB1158850A (pl)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4204459A (en) * 1978-04-19 1980-05-27 Caterpillar Tractor Co. Combination check and flow control valve for hydraulic systems
EP0207639A1 (en) * 1985-06-03 1987-01-07 Samco-Strong Limited Control device for a hydraulic press
CN102699670A (zh) * 2012-05-31 2012-10-03 韶关东南轴承有限公司 基于速度与压力联合控制的铆装装置
US20140034135A1 (en) * 2012-07-31 2014-02-06 Caterpillar Inc. Hydraulic system with a dynamic seal
CN111520368A (zh) * 2020-04-21 2020-08-11 中联重科股份有限公司 负载敏感系统的流量分配控制方法

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3722366A (en) * 1971-03-22 1973-03-27 Pacific Press & Shear Corp Precision anti-whip ram type machine
CN111550474B (zh) * 2020-05-07 2022-03-22 徐州徐工液压件有限公司 用于双缸同步负载侧向力试验台的液压系统

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2431032A (en) * 1943-04-05 1947-11-18 Hpm Dev Corp Flow controlling valve means for hydraulic motors
US2470778A (en) * 1946-06-25 1949-05-24 Matthew B Butler Hydraulic system for selfloading trucks
US2648346A (en) * 1952-05-19 1953-08-11 Bendix Aviat Corp Locking valve for hydraulic motors
US2872903A (en) * 1956-11-13 1959-02-10 Emhart Mfg Co Fluid lock valve
US3015316A (en) * 1959-01-08 1962-01-02 William Waterman Counterbalance valves and the like
US3071926A (en) * 1960-04-12 1963-01-08 Hyster Co Hydraulic lift cylinder circuit
US3169453A (en) * 1962-03-26 1965-02-16 New York Air Brake Co Valve
US3349669A (en) * 1966-04-20 1967-10-31 Rolland A Richardson Ram attitude control system
US3381587A (en) * 1965-09-10 1968-05-07 Deere & Co Hydraulic control system

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2431032A (en) * 1943-04-05 1947-11-18 Hpm Dev Corp Flow controlling valve means for hydraulic motors
US2470778A (en) * 1946-06-25 1949-05-24 Matthew B Butler Hydraulic system for selfloading trucks
US2648346A (en) * 1952-05-19 1953-08-11 Bendix Aviat Corp Locking valve for hydraulic motors
US2872903A (en) * 1956-11-13 1959-02-10 Emhart Mfg Co Fluid lock valve
US3015316A (en) * 1959-01-08 1962-01-02 William Waterman Counterbalance valves and the like
US3071926A (en) * 1960-04-12 1963-01-08 Hyster Co Hydraulic lift cylinder circuit
US3169453A (en) * 1962-03-26 1965-02-16 New York Air Brake Co Valve
US3381587A (en) * 1965-09-10 1968-05-07 Deere & Co Hydraulic control system
US3349669A (en) * 1966-04-20 1967-10-31 Rolland A Richardson Ram attitude control system

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4204459A (en) * 1978-04-19 1980-05-27 Caterpillar Tractor Co. Combination check and flow control valve for hydraulic systems
EP0207639A1 (en) * 1985-06-03 1987-01-07 Samco-Strong Limited Control device for a hydraulic press
CN102699670A (zh) * 2012-05-31 2012-10-03 韶关东南轴承有限公司 基于速度与压力联合控制的铆装装置
CN102699670B (zh) * 2012-05-31 2015-03-04 韶关东南轴承有限公司 基于速度与压力联合控制的铆装装置
US20140034135A1 (en) * 2012-07-31 2014-02-06 Caterpillar Inc. Hydraulic system with a dynamic seal
US9651067B2 (en) * 2012-07-31 2017-05-16 Caterpillar Inc. Hydraulic system with a dynamic seal
CN111520368A (zh) * 2020-04-21 2020-08-11 中联重科股份有限公司 负载敏感系统的流量分配控制方法
CN111520368B (zh) * 2020-04-21 2022-03-04 中联重科股份有限公司 负载敏感系统的流量分配控制方法

Also Published As

Publication number Publication date
FR1548216A (pl) 1968-11-29
BE708654A (pl) 1968-05-02
GB1158850A (en) 1969-07-23
DE1627857A1 (de) 1969-10-30

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