GB2311331A - Hydraulic ram booster - Google Patents

Hydraulic ram booster Download PDF

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Publication number
GB2311331A
GB2311331A GB9705691A GB9705691A GB2311331A GB 2311331 A GB2311331 A GB 2311331A GB 9705691 A GB9705691 A GB 9705691A GB 9705691 A GB9705691 A GB 9705691A GB 2311331 A GB2311331 A GB 2311331A
Authority
GB
United Kingdom
Prior art keywords
primary
cylinder
piston
fluid
stroke
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.)
Withdrawn
Application number
GB9705691A
Other versions
GB9705691D0 (en
Inventor
Stephen Ruff
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.)
TT Boughton and Sons Ltd
Original Assignee
TT Boughton and Sons Ltd
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
Application filed by TT Boughton and Sons Ltd filed Critical TT Boughton and Sons Ltd
Publication of GB9705691D0 publication Critical patent/GB9705691D0/en
Publication of GB2311331A publication Critical patent/GB2311331A/en
Withdrawn legal-status Critical Current

Links

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
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
    • F15B11/036—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force by means of servomotors having a plurality of working chambers
    • F15B11/0365—Tandem constructions
    • 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
    • F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
    • F15B11/036—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force by means of servomotors having a plurality of working chambers
    • 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
    • F15B2211/21—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge
    • F15B2211/214—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge the pressure sources being hydrotransformers
    • 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
    • F15B2211/30505—Non-return valves, i.e. check 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
    • F15B2211/50518—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
    • 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
    • F15B2211/775—Combined control, e.g. control of speed and force for providing a high speed approach stroke with low force followed by a low speed working stroke with high force, e.g. for a hydraulic press

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Actuator (AREA)

Abstract

There is described a fluid operated actuator comprising primary and secondary pressurisable cylinders (1, 8) in which primary and secondary piston assemblies (2, 3, 6, 7) comprising primary and secondary pistons (2, 6) and primary and secondary piston rods (3, 7), respectively, are sealingly slidable, the secondary cylinder and piston assembly (6, 7, 8) being of shorter stroke than the primary, and the primary (1, 2, 3) and secondary piston assemblies (6, 7, 8) further comprising respective abutment surfaces adapted to be in abutting relation when the primary piston (2) is at one end part of its stroke, the arrangement being such that as pressurised fluid is supplied to both the primary and secondary cylinders with the primary piston assembly (1, 2) at the one end part of its stroke, the pressurised fluid causes both pistons (2, 6) to exert a force on the primary piston rod (3) until the secondary piston assembly (6, 7) reaches the end of its stroke. The primary and secondary pressurisable cylinders (1, 8) are preferably coaxial, with the secondary piston rod (7) extending through an end wall (4) of the primary cylinder (1) to abut the primary piston (2) when the latter is near the end of its stroke.

Description

HYDRAULIC RAM BOOSTER The present invention relates to hydraulic actuators, and is particularly concerned with increasing the available actuating force at the ends of the stroke of a linear hydraulic actuator or ram.
In devices in which hydraulic rams are used to operate swinging booms, to maximise boom movement for a given ram stroke it is often the case that the initial and final parts of the movement of the boom require substantial torque to be exerted by the boom, at a time when the moment arm of the ram force is at a minimum. Such situations arise for example when an arm is used to raise a load, where if the arm is initially horizontal the moment due to the load is at a maximum whereas the moment available from a ram attached to the arm may not be at its maximum due to the geometry of the device.
The present invention seeks to provide a linear actuator which is simple in construction, compact, and provides an increased actuating force over the starting and/or ending portions of its stroke. The actuator is particularly suited to applications where the end positions of the movement of the load are fixed, such as in many mechanical handling installations.
According to the present invention, a fluid operated actuator comprises a primary and secondary pressurisable cylinders in which primary and secondary piston assemblies comprising primary and secondary pistons and primary and secondary piston rods, respectively, are sealingly slidable, the secondary cylinder and piston assembly being of shorter stroke than the primary, and the primary and secondary piston assemblies being in abutting relation when the primary piston is at one end part of its stroke, the arrangement being such that as pressurised fluid is supplied to both the primary and secondary cylinders with the primary piston assembly at the one end part of its stroke, it causes both piston assemblies to exert a force on the primary piston rod until the secondary piston assembly reaches the end of its stroke.
The pressurised fluid may be hydraulic fluid, or may be compressed gas, fed from a pump or from a high pressure reservoir.
Preferably, the primary and secondary pressurisable cylinders are coaxial, and the secondary piston rod extends through an end wall of the primary cylinder to abut the primary piston when the latter is near the end of its stroke. In this arrangement, the pressurised fluid may be fed to the working chamber of the primary cylinder via a port leading to the working chamber of the secondary cylinder and thence via a passage passing through the secondary piston assembly.
Alternatively, a first port which allows fluid to enter and leave the working chamber of the primary cylinder, and a separate second port which allows fluid to enter and leave the working chamber of the secondary cylinder, may be provided. Such an arrangement of fluid supply ports is advantageous when the primary and secondary cylinders are arranged side by side, and abutments are provided on the piston rods to transmit force from the secondary piston rod to the primary and vice versa. Most preferably, flow passages may be provided between the first and second ports, and valves may be arranged in the flow passages to allow flow of fluid from the first port to the second port only when a predetermined pressure is exceeded in the primary cylinder, and to allow flow of fluid from the second port to the first port only when pressure in the secondary cylinder exceeds that in the primary cylinder. This predetermined pressure may be set at, for example, from 10 to 90% of the maximum working pressure.
In a further embodiment, a primary cylinder may be provided at both its ends with secondary cylinders of shorter stroke, the pressurised fluid supply being such that as the primary piston assembly is moved in one or the other sense within the primary cylinder, the secondary cylinder towards which the primary piston assembly is moving is not supplied with fluid, whereas the secondary cylinder away from which the primary piston assembly is moving is supplied with fluid to extend its piston assembly towards the primary piston assembly.
The primary and secondary pressurisable cylinders are preferably of the same diameter, but the secondary cylinder may be of greater or smaller diameter than the primary.
An embodiment of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 is a sectional view of an end of an actuator.
Figure 2 shows the actuator in an extended position.
Figure 3 is a view similar to Figure 1 of an alternative embodiment of the invention, in a position similar to the actuator of Figure 1.
Referring now to Figures 1 and 2, the actuator comprises a main cylinder 1 wherein a main piston assembly is slidable, The main piston assembly comprises a main piston 2 and a main piston rod 3.
The end wall 4 of the main cylinder 1 is formed with an opening 5 through which an auxiliary piston rod 6, attached to an auxiliary piston 7, is sealingly slidable. The auxiliary piston 7 is housed in an auxiliary cylinder 8, coaxial with the main cylinder 1 and having the same diameter. An end wall 8a closes the end of the auxiliary cylinder 8 remote from the main cylinder 1.
Pressurised fluid is admitted to and exhausted from the working chamber of the auxiliary cylinder 8 via a single inlet/outlet port 9, and a passageway 10 passes through the auxiliary piston 7 and the auxiliary piston rod 6, to open radially of the auxiliary piston rod 6 at its end remote from the auxiliary piston 7. The passageway 10 affords fluid communication between the working chamber of the main cylinder 1 and the inlet/outlet port 9, as will be seen below.
The volume between the auxiliary piston 6 and the end wall 4 is preferably provided with an exhaust port 11, to collect any fluid leaking past the seals of the auxiliary piston 6 and the auxiliary piston rod 7 and return it to a fluid reservoir (not shown) of the hydraulic system.
In operation, when the actuator is at the beginning of its stroke, the main piston 2 is adjacent the end wall 7 and the auxiliary piston 6 is adjacent the end wall 8a. As pressurised fluid is supplied to the port 9, fluid pressure is exerted on the auxiliary piston 6, and via the passageway 10 on the main piston 2. The auxiliary piston rod 7 transmits the force of the auxiliary piston 6 to the main piston 2, by the abutting relation of the end of the auxiliary piston rod 7 and the main piston The force exerted on the main piston rod at this time is thus the product of the fluid pressure and the area of the auxiliary piston 6 plus the area of the main piston 2 minus the cross-section of the auxiliary piston rod 7.
The main piston 2 and the auxiliary piston 6 move to the right (as seen in the Figure) until the auxiliary piston 6 reaches the end wall 4. At this point the auxiliary piston rod 7 separates from the main piston 2, and the main piston 2 continues moving to the right but with a reduced force, now equal to the product of the fluid pressure and the area of the main piston 2. The passageway 10 allows fluid to pass from the port 9, through the working chamber of the auxiliary piston, through the auxiliary piston rod 7 and into the working chamber of the main cylinder to complete the movement of the actuator.
To return the actuator to its start position, pressurised fluid is admitted to the main cylinder to the right (as seen in the Figures) of the main piston, and the port 9 is connected to the reservoir of the system to return the fluid from the main cylinder and auxiliary cylinder.
The auxiliary piston rod 7 remains extended into the main cylinder 1 until the main piston 2 contacts it to urge it back into the auxiliary cylinder 8. During this part of the travel, the fluid in the end part of the main cylinder is exhausted simultaneously with the fluid in the auxiliary cylinder 8, and the throttling action of the port 9 can assist in cushioning the final part of the travel of the actuator.
While the present embodiment shows one end of an actuator only, it is to be understood that both ends of the main cylinder may be provided with auxiliary piston and cylinder assemblies. Likewise, the auxiliary piston and cylinder assemblies need not be coaxial with the main cylinder, but may be mounted alongside in parallel, with lost motion connections between the main piston assembly and the auxiliary piston assembly or assemblies. It is also foreseen that two or more auxiliary piston and cylinder assemblies may be mounted at one or each end of the main cylinder.
In the embodiment shown in Figure 3, each of the main and auxiliary cylinders has a respective inlet port 9 and 9a, and pressurised fluid is supplied to the main cylinder through port 9a. The auxiliary piston is solid (i.e. no passage 10 is present as in Figure 1), allowing no communication between the auxiliary cylinder 8 and the main cylinder 1 except via the ports 9 and 9a.
A pressure relief valve 20 is connected between the port 9a and the port 9 feeding the auxiliary cylinder 8, so that fluid is supplied to the auxiliary cylinder 8 only when the fluid pressure at the port 9a exceeds a predetermined proportion of the maximum working pressure.
Preferably the predetermined proportion is some 50%, but values of from 10 to 95% are contemplated. The pressure relief valve 20 is preferably a two-stage pilot operated pressure relief valve.
Also connected between the ports 9 and 9a is a non-return valve 21, allowing fluid to pass out of but not into the auxiliary cylinder 8.
This non-return valve may be advantageously a two-stage pilot operated non-return valve.
In operation, the combination of the pressure relief valve 20 and the non-return valve 21 act to allow fluid into the auxiliary cylinder 8 only when the load on the main ram causes the pressure in the working chamber of the main cylinder to rise to above the predetermined proportion of the maximum permitted pressure, i.e. when the ram is heavily loaded.
Under light loads, the back pressure from the main cylinder is insufficient to open the pressure relief valve 20 and allow fluid to pass into the auxiliary cylinder 8, and the load is then moved by the main cylinder and piston assembly alone. When the load is such that the back pressure from the main cylinder at the port 9a exceeds the predetermined proportion of the maximum working pressure, the pressure relief valve 20 opens to supply fluid at high pressure to the auxiliary cylinder 8, and the auxiliary piston 7 moves to abut the main piston. Subsequent movement of the two piston assemblies is slower, but greater force is achieved than by the main piston alone.
As pressurised fluid is admitted to the main cylinder to the right of the main piston and the port 9a is connected to the reservoir of the system to return the fluid from the main cylinder 1, the actuator returns towards its retracted position. The fluid in the auxiliary cylinder is prevented from leaving the cylinder by the valves 20 and 21, and the auxiliary piston rod 7 thus remains extended into the main cylinder 1. When the main piston 2 contacts the auxiliary piston rod 7, it is urged back into the auxiliary cylinder 8. During this final part of the travel, the pressure of the fluid in the auxiliary cylinder 8 is raised by the force exerted on the auxiliary piston rod 7, and the fluid is exhausted through the port 9, the non-return valve 21, and the port 9a and so to the reservoir.

Claims (9)

1. A fluid operated actuator comprising primary and secondary pressurisable cylinders in which primary and secondary piston assemblies comprising primary and secondary pistons and primary and secondary piston rods, respectively, are sealingly slidable, the secondary cylinder and piston assembly being of shorter stroke than the primary, and the primary and secondary piston assemblies further comprising respective abutment surfaces adapted to be in abutting relation when the primary piston is at one end part of its stroke, the arrangement being such that as pressurised fluid is supplied to both the primary and secondary cylinders with the primary piston assembly at the one end part of its stroke, the pressurised fluid causes both pistons to exert a force on the primary piston rod until the secondary piston assembly reaches the end of its stroke.
2. An actuator according to Claim 1, wherein the primary and secondary pressurisable cylinders are coaxial, and the secondary piston rod extends through an end wall of the primary cylinder to abut the primary piston when the latter is near the end of its stroke.
3. An actuator according to Claim 2, wherein the secondary piston and piston rod are formed with a passage providing fluid communication between the working chambers of the primary and secondary cylinders.
4. An actuator according to Claim 1 or Claim 2, wherein a supply of pressurised fluid is selectively connectable to a first port which allows fluid to enter and leave the working chamber of the primary cylinder and to a second port which allows fluid to enter and leave the working chamber of the secondary cylinder.
5. An actuator according to Claim 4, wherein flow passages are provided between the first and second ports, and valves are arranged in the flow passages to allow flow of fluid from the first port to the second port only when a predetermined pressure is exceeded in the primary cylinder, and to allow flow of fluid from the second port to the first port only when pressure in the secondary cylinder exceeds that in the primary cylinder.
6. An actuator according to any preceding Claim, wherein the primary cylinder is provided at both its ends with respective secondary cylinders of shorter stroke than the primary, the pressurised fluid supply being such that as the primary piston assembly is moved in one or the other sense within the primary cylinder, the secondary cylinder towards which the primary piston assembly is moving is not supplied with fluid, whereas the secondary cylinder away from which the primary piston assembly is moving is supplied with fluid so as to urge its piston assembly to move in the direction of travel of the primary piston assembly.
7. An actuator according to any preceding Claim, wherein the pressurised fluid is hydraulic fluid fed from a pump.
7. An actuator according to any preceding Claim, wherein the primary and secondary pressurisable cylinders are of circular cross-section and have the same diameter.
8. An actuator according to any of Claims 1 to 7, wherein the primary and secondary pressurisable cylinders are of circular cross-section and the secondary cylinder is of greater diameter than the primary.
9. A fluid operated actuator substantially as herein described, with reference to Figures 1 and 2, or Figure 3, of the accompanying drawings.
GB9705691A 1996-03-22 1997-03-19 Hydraulic ram booster Withdrawn GB2311331A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GBGB9606077.7A GB9606077D0 (en) 1996-03-22 1996-03-22 Hydraulic ram booster

Publications (2)

Publication Number Publication Date
GB9705691D0 GB9705691D0 (en) 1997-05-07
GB2311331A true GB2311331A (en) 1997-09-24

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Family Applications (2)

Application Number Title Priority Date Filing Date
GBGB9606077.7A Pending GB9606077D0 (en) 1996-03-22 1996-03-22 Hydraulic ram booster
GB9705691A Withdrawn GB2311331A (en) 1996-03-22 1997-03-19 Hydraulic ram booster

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GBGB9606077.7A Pending GB9606077D0 (en) 1996-03-22 1996-03-22 Hydraulic ram booster

Country Status (1)

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GB (2) GB9606077D0 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0993910A2 (en) * 1998-10-14 2000-04-19 Framatome Connectors International S.A. Hydraulic tool with rapid ram advance
EP1270959A2 (en) * 2001-06-18 2003-01-02 Fci Hydraulic tool having mechanical actuator with internal bypass valve

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1076188A (en) * 1963-12-03 1967-07-19 British Aircraft Corp Ltd Improved stall-correcting apparatus for aircraft
GB1496647A (en) * 1975-06-05 1977-12-30 Voith Gmbh J M Lifting devices for web handling apparatus
GB1571046A (en) * 1976-03-03 1980-07-09 Westin & Backlund Ab Regulators
GB2058924A (en) * 1979-09-17 1981-04-15 Mercer Nairne & Co Ltd Pressure fluid assembly
US4555979A (en) * 1984-08-06 1985-12-03 Robert Cetnarowski Fluid-powered multiple pistonrod lift unit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1076188A (en) * 1963-12-03 1967-07-19 British Aircraft Corp Ltd Improved stall-correcting apparatus for aircraft
GB1496647A (en) * 1975-06-05 1977-12-30 Voith Gmbh J M Lifting devices for web handling apparatus
GB1571046A (en) * 1976-03-03 1980-07-09 Westin & Backlund Ab Regulators
GB2058924A (en) * 1979-09-17 1981-04-15 Mercer Nairne & Co Ltd Pressure fluid assembly
US4555979A (en) * 1984-08-06 1985-12-03 Robert Cetnarowski Fluid-powered multiple pistonrod lift unit

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0993910A2 (en) * 1998-10-14 2000-04-19 Framatome Connectors International S.A. Hydraulic tool with rapid ram advance
EP0993910A3 (en) * 1998-10-14 2002-01-16 Framatome Connectors International S.A. Hydraulic tool with rapid ram advance
EP1270959A2 (en) * 2001-06-18 2003-01-02 Fci Hydraulic tool having mechanical actuator with internal bypass valve
EP1270959A3 (en) * 2001-06-18 2008-09-17 Fci Hydraulic tool having mechanical actuator with internal bypass valve

Also Published As

Publication number Publication date
GB9606077D0 (en) 1996-05-22
GB9705691D0 (en) 1997-05-07

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