Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
  • B25B21/00—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose
  • B25B21/004—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose of the ratchet type
  • B25B21/005—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose of the ratchet type driven by a radially acting hydraulic or pneumatic piston

Definitions

• This invention relates to torque wrenches.
• a torque wrench which is 5 hydraulically-operated by a piston and cylinder device and also includes a ratchet mechanism.
• European patent specification Number 62195A shows a wrench in which a form of. knee joint linkage is used to transmit pressure from a s piston in one part of the wrench to another part of the wrench, so that relative movement takes place between the 20 two parts, thereby turning a nut(or bolt) - engaging socket.
• a similar knee joint is used in association with a pawl and ratchet mechanism, to facilitate the return of the two wrentch parts to their starting point, for the next power stroke of the piston and cylinder device.
• a hydraulic torque wrench of the kind comprising two parts which are relatively movable about: a common axis of rotation with an associated ratchet and pawl mechanism, under the influence of a piston and cylinder device, is characterised in that the piston and cylinder device includes a hollow piston having a slot defined in a sidewall thereof and a distal portion of one of said relatively movable parts projects through said slot and through a corresponding slot in the cylinder into the hollow piston, to which it is operably connected only through a linkage between the piston at one end and said distal portion at the other end.
• “Operably connected” means for present purposes that the linkage is not necessarily positively attached to the piston, for example by a pin, or to the distal portion, or to both of these. In some embodiments it may be more convenient to have no such positive connection between the linkage and the piston. For example, the otherwise free end of the linkage may be located within a recess or hollow in the piston. Operably-connected means in this case that the linkage can exert positive pressure in only one direction. For practical purposes this may be all that is actually necessary.
• the hollow piston may be of unitary construction, closed at both ends.
• the return stoke of the piston and cylinder (prior to the next power stroke) may in this case be accomplished by applying hydraulic pressure to that end of the piston opposite to the end operably connected to the linkage.
• a second independant and oppositely-directed piston may be provided in back-to-back relation to the first piston.
• the oppositely- directed piston may be constructed to apply pressure directly against the open end of the first piston, to cause the latter to make the return stroke.
• the oppositely directed piston may be operably connected to the same distal portion of one of the movable parts only through a linkage operably connected to the second piston at one end and to the distal portion at the other end.
• FIG. 1 of the accompanying drawings illustrates the features of a torque wrench constructed in accordance with the invention.
• the drawing is a side elevation, partly in section, from which aspects not directly relevant to the invention have either been omitted, or are not shown in great detail.
• a wrench body (1) with hydraulic fluid connectors (2) and a carrying handle (3) contains a pawl foot (4) and ratchet wheel (5), the latter driving a socket tool (6).
• the socket (6) is accessible through the wrench body?
• the pawl foot (4) is spring biassed in conventional manner (7) into wedging engagement with the ratchet wheel (5), with the aid of a cam surface (8) constituted by one side of an opening in a relatively movable member (9) located inside the wrench body (1).
• the member (9) has a distal portion (10).
• the body (1) also contains a piston (11) in a cylinder (12) .
• the piston is hollow, with a piston head (13), (14) at each end.
• the piston is in two parts (15), (16) united by a screw-threaded connection (17).
• Annular seals (18) are provided adjacent each piston head; each of the two fluid connectors (2) communicates with its own respective end of the cylinder (12) .
• Both the piston and the cylinder have slots machined in them (not explicity shown, but in the region 19) to allow the distal portion (10) to project into the hollow piston.
• the free end of the distal portion has one end of a linkage (20) pivotally, attached to it.
• the opposite end of the linkage is connected to the inside of the piston head (13), by a pivot pin,. (21).
• the regions (22) or (23) of the body (1) may be abutted against the next nut in a series which are to be tightened (or released) .
• the fluid pressure can be applied at the other end of the cylinder, to piston head (13). This then moves to the left in the figure, causing the distal portion (10) to do the same. This rotates the member (9) anti-clockwise; this in turn releases the pawl foot (4) from the cam surface (8) so that only the spring (7) holds it against the ratchet wheel.
• the pawl foot (4) will lift off the ratchet wheel allowing the member (9) to return to its starting position. The operation is repeated as desired.
• FIG. 2 of the accompanying drawings shows a further embodiment of the invention.
• two separate pistons, 40 and 41 are provided and there are two linkages 42, 43 corresponding to the single linkage 20 of Figure 1.
• these linkages are pivotally connected to the distal portion 10 of the common member 9.
• Figure 3 of the accompanying drawings illustrates a modification of the two piston arrangement shown in Figure 2.
• the linkages 42, 43 are shown, on an enlarged scale.
• a coil spring 50 is provided in order to urge the linkages towards one another and into contact with the actuator (10, in Figure 2) .
• the spring extends into bores 51, 52 in the respective linkages and the ends of the spring are retained by set screws 53, 54 respectively, so that the spring is under tension.
• the linkages are thus biassed towards one another and against th actuator 10.
• a second spring diametrically opposite t the first one will usually be used, to ensure that the biassing: force is symmetrically disposed about the common axis of: the linkages.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10587040

Family Applications (1)

Country Status (3)

Families Citing this family (4)

Family Cites Families (9)

• 1985
  • 1985-10-22 GB GB858525983A patent/GB8525983D0/en active Pending
• 1986
  • 1986-10-20 EP EP19860906374 patent/EP0246262A1/de active Pending
  • 1986-10-20 WO PCT/GB1986/000640 patent/WO1987002610A1/en unknown
  • 1986-10-20 GB GB08625129A patent/GB2182592A/en not_active Withdrawn

Non-Patent Citations (1)

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