GB1602096A - Torque wrenches - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO TORQUE WRENCHES (71) We, TURNER AITKEN MFG, CO, LTD., a British Company, of 49 The Grove, Ealing, London, W.5, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to torque wrenches of the kind comprising an elongate tubular housing, a tool head projecting from one end of the housing and rigid with the outer end of a lever or bar pivotally mounted in said one end of the housing, a spring mounted in the other end of the housing between a plunger slidably mounted in the housing and manually-operable means projecting from said other end of the housing for adjusting the loading of the spring.

The force of the spring is usually transmitted via the plunger to the inner end of the lever through a movable thrust member such as a ball and it is a principal object of the present invention to provide inproved means for transmitting force between the spring-loaded plunger and the lever or bar, which means is relatively inexpensive to produce, easy to assemble and efficient in operation, and to this end, according to the invention, a cam pivotally mounted in the tool housing for movement about an axis parallel with the pivotal axis of the lever between two extreme positions determined by engagement of a projection thereon with opposite sides of the housing, is connected on one side of its pivot to the inner end of the lever and on the other side of its pivot to one end of a link, the other end of which engages a seat on said plunger.

A preferred form of the invention will be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a side elevation, partly in section, of a tool constructed in accordance with the invention; Figure 2 in a view similar to that shown in Fig. 1 with the tool turned through 90 ; and Figure 3 is a vertical section through the right-hand end of the tool in the position shown in Fig. 2.

As shown in the drawing, a tool head 1 is formed integral With a lever or bar 2 which is pivotally mounted at 3 in one end of a tubular housing 4. The lever 2 has a forked inner end 5 which engages around, and is pivotally connected at 6 to, one end of a cam 7 pivotally mounted at 8 in a grooved block 9 slidably mounted in the housing 4.

The block 9 also receives the forked end 10 of a link 11 which is pivotally connected at 12 to the cam 7 and is seated at its other end in a recess 13 in the face of a plunger 14, the two halves 15, 16 of which are differently coloured. The latter is engaged by one end of a compression spring 17, the other end of which is engaged by an internally threaded collar 18 (Fig. 3) which closes one end of a sleeve 19. The collar 18 is mounted on a threaded spindle 20, the outer end of which is secured within a blind bore 21 in a knob 22 by a grub screw 23. The knob 22 is positioned externally of the housing 4 and is manually rotatable to vary the load on the spring 17, the value of the load being indicated by calibrations 24 (Fig. 1) on the sleeve 19 which are visible through an aperture 25 in the housing.To ensure that the calibrations on the sleeve 19 are always visible to the operator the sleeve is formed with. a guide slot 26 (Fig. 2) which cooperates with a locating stud 27 in the wall of the housing 4.

With the tool in the condition shown in Figs. 1 and 2 in which the half 16 of the plunger 14, which half may be coloured red, shows through holes 28 in the housing 4, the loading on the spring 17 is adjusted to the required value by rotation of the knob 22 and the tool head 1 is fitted over the member to be tightened. The tool is then operated until the applied torque is sufficient to overcome the holding force exerted on the inner end of the lever 2 by the spring 17 acting through the plunger 14, link 11 and cam 7.

The cam 7 then rotates about its pivot 8 forcing the link 11 and plunger 14 rearwardly until the half 15 of the plunger, which half may be coloured green, is visible through the holes 28 in the housing 4 and the inner end of the lever 2 moves transversely across the housing until the nose portion of the cam strikes the opposite wall of the housing.

The cam 7 and its associated parts 9, 11, 14 for transmitting force between the spring 17 and the lever 2 may, with advantage, be made of synthetic plastics material.

The different colours may be simply applied to the plunger by wrapping a twocoloured vinyl adhesive tape around the outside thereof.

WHAT WE CLAIM IS: 1. A torque wrench comprising an elongate tubular housing, a tool head projecting from one end of the housing and rigid with the outer end of a lever or bar pivotally mounted in said one end of the housing, a spring mounted in the other end of the housing between a plunger slidably mounted in the housing and manuallyoperable means projecting from said other end of the housing for adjusting the loading of the spring, and a cam pivotally mounted in the housing for movement, about an axis parallel with the pivotal axis of the lever, between two extreme positions determined by engagement of a projection on the cam with opposite sides of the housing, said cam being connected on one side of its pivot to the inner end of the lever and on the other side of its pivot to one end of a link, the other end of which engages a seat on said plunger.

2. A torque wrench according to Claim 1, wherein the inner ends of said lever and said link are forked for pivotal connection to said cam which is pivotally mounted in a grooved block slidably arranged in said housing and apertured for the passage of the forked end of the link.

3. A torque wrench according to Claim 1 or 2, wherein the plunger has two differently coloured sections which are alternately visible through apertures in the housing dependent upon whether the force generated .by the torque being applied through the tool head is greater or less than the spring force on the plunger. - 4. A torque wrench according to any one of Claims 1 to 3, wherein the outer end of said spring is engaged by an internally threaded collar movable longitudinally of the housing along a threaded spindle in response to manual rotation of an external knob attached to said spindle and constituting said manually operable means for varying the load on the spring.

5. A torque wrench according to Claim 4, wherein said collar is secured to one end of a sleeve surrounding said spring and provided on its outer surface with calibrations which are visible through an aperture in the housing to indicate the load applied to the spring.

6. A torque wrench according to Claim 5, wherein said sleeve is prevented from rotating relative to the housing by a stud which projects from said housing into a longitudinally extending slot in said sleeve.

7. A torque wrench according to any preceding claim, wherein said cam and the parts associated therewith for transmitting force between the spring and the lever are made of synthetic plastics material.

8. A torque wrench substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. the spring 17 acting through the plunger 14, link 11 and cam 7. The cam 7 then rotates about its pivot 8 forcing the link 11 and plunger 14 rearwardly until the half 15 of the plunger, which half may be coloured green, is visible through the holes 28 in the housing 4 and the inner end of the lever 2 moves transversely across the housing until the nose portion of the cam strikes the opposite wall of the housing. The cam 7 and its associated parts 9, 11, 14 for transmitting force between the spring 17 and the lever 2 may, with advantage, be made of synthetic plastics material. The different colours may be simply applied to the plunger by wrapping a twocoloured vinyl adhesive tape around the outside thereof. WHAT WE CLAIM IS:

1. A torque wrench comprising an elongate tubular housing, a tool head projecting from one end of the housing and rigid with the outer end of a lever or bar pivotally mounted in said one end of the housing, a spring mounted in the other end of the housing between a plunger slidably mounted in the housing and manuallyoperable means projecting from said other end of the housing for adjusting the loading of the spring, and a cam pivotally mounted in the housing for movement, about an axis parallel with the pivotal axis of the lever, between two extreme positions determined by engagement of a projection on the cam with opposite sides of the housing, said cam being connected on one side of its pivot to the inner end of the lever and on the other side of its pivot to one end of a link, the other end of which engages a seat on said plunger.

2. A torque wrench according to Claim 1, wherein the inner ends of said lever and said link are forked for pivotal connection to said cam which is pivotally mounted in a grooved block slidably arranged in said housing and apertured for the passage of the forked end of the link.

3. A torque wrench according to Claim 1 or 2, wherein the plunger has two differently coloured sections which are alternately visible through apertures in the housing dependent upon whether the force generated .by the torque being applied through the tool head is greater or less than the spring force on the plunger. -

4. A torque wrench according to any one of Claims 1 to 3, wherein the outer end of said spring is engaged by an internally threaded collar movable longitudinally of the housing along a threaded spindle in response to manual rotation of an external knob attached to said spindle and constituting said manually operable means for varying the load on the spring.

5. A torque wrench according to Claim 4, wherein said collar is secured to one end of a sleeve surrounding said spring and provided on its outer surface with calibrations which are visible through an aperture in the housing to indicate the load applied to the spring.

6. A torque wrench according to Claim 5, wherein said sleeve is prevented from rotating relative to the housing by a stud which projects from said housing into a longitudinally extending slot in said sleeve.

7. A torque wrench according to any preceding claim, wherein said cam and the parts associated therewith for transmitting force between the spring and the lever are made of synthetic plastics material.

8. A torque wrench substantially as hereinbefore described with reference to and as shown in the accompanying drawings.