AU721961B2 - Improved torque wrench/tension wrench - Google Patents

Description

Technical Field This invention relates to an improvement in the design and construction of a Torque Wrench, also known as a Tension Wrench. The invention seeks to eliminate the present complexity and consequent high cost for minimal reduction in functionality.

Background Art Torque Wrenches are like spanners with an additional feature: they do not permit more than a user-set degree of lateral force on the handle. This feature limits the amount of twist, tension or torque possible on the nut being tightened. The limit is desirable where over-tightening would be a problem or where attempts to avoid over-tightening may 1o produce under-tightening.

The methodology resides in a ratchet coupling built into the handle which can be adjusted to "break" meaning permit the coupling to give way and rotate once a certain degree of lateral force is applied by the user, as in the familiar act of moving the handle to tighten a nut.

Lateral force applied by the user is transmitted from the handle to the spanner head.

The ratchet coupling on torque wrenches is located between the force applied by the user to the handle and the nut being tightened. It thereby controls the force possible by becoming the point of least resistance.

Torque Wrenches perform well but are expensive, retailing in Australia for a high 20 cost, presently from $150 to $400. The extremely high cost of this tool is amplified because they are often used on installation sites which are temporary and unfamiliar and the tool can o° ~be lost or, being costly and desirable, stolen.

oo: As an alternative to torque wrenches, tradespeople and consumers often choose to, or are instructed to, tighten a nut or similar fastener "finger tight only" or by some other 25 inexact level of human judgment. This is a concession to economy and expediency and produces an unknown degree of tension, which may not be desirable but may be necessary due to the high cost of torque wrenches and lack of a cheaper alternative.

Objects of this Invention To permit the production of an effective tension wrench for less cost by eliminating 0o•* 30 the need for an adjustable ratchet coupling, any ratchet coupling or any slip or rotating device designed to limit torque.

To replace the adjustable multi-tension handles of torque wrenches in the background art with torque wrenches including preset tension handles that possess a fixed torque- 1' ting capability.

C.)

A S [R:\LIBZZ]06476.doc:NJC To replace the ratchet coupling torque wrenches with a handle of inherent flexibility in torque wrenches such that the flexibility provides the torque limitation in lieu of a coupling or ratchet.

To use material in the torque wrench handle that provides consistent flexure or resistance to flexure within intended design tolerances.

To produce a variant of the torque wrench with fixed heads and handles that are not interchangeable but combine a single flexible handle and with a single spanner head or any other desired head. To produce a variant of the torque wrench with a second grip on the handle permitting a second preset torque limitation from the one unit.

0o Disclosure of invention According to a first embodiment of this invention there is provided a tension wrench or spanner comprising a wrench or spanner head, a flexible arm or handle, at least one hand grip positioned along or at an end of said flexible arm or handle, wherein said spanner or wrench head co-operates with said flexible arm or handle, in a manner such that said tension wrench is limited in use to a predetermined torque value without the use of a ratchet coupling.

According to a second embodiment of this invention there is provided a tension wrench as described in the first embodiment of this invention wherein the wrench or spanner head is connected to a first end of the flexible arm or handle which is opposed to :20 the hand grip which is located at a second end of the flexible arm or handle.

a According to a third embodiment of this invention there is provided a tension wrench oool as described in the first or second embodiment of this invention wherein the wrench or spanner head is integrally formed with the flexible arm or handle.

i, According to a fourth embodiment of this invention there is provided a tension wrench 25 as described in the first or second embodiment of this invention wherein the spanner head is detachably found attached with the flexible arm or handle.

According to a fifth embodiment of this invention there is provided a tension wrench as described in any one of the first to fourth embodiments of this invention wherein the flexible arm or handle has a first hand grip located at one end and a second hand grip S 30 located towards the centre of the flexible arm or handle.

(they would all be "seasoned" like this. Only after constant flexing does polypropylene develop uniform resistance to flexing.) According to a sixth embodiment of this invention there is provided a tension wrench as described in any one of the first to fifth embodiments of this invention wherein the [R:\L1BZZ]06476.doc:NJC wrench or spanner is made from a material that has been pre-stressed or pre-flexed to stabilise flexure or resistance to within predetermined torque values.

According to a seventh embodiment of this invention there is provided a method of tightening a nut, bolt or the like using a tension wrench or spanner according to any one of the First to sixth embodiments of this invention.

According to another embodiment of this invention there is provided a tension wrench comprising an arm or handle made of polypropylene, polyethylene or any material possessing suitable flexibility and elasticity. Typically, such desired flexibility of said arm or handle is regulated by the thickness and length of the arm or handle at manufacture in consideration of the inherent characteristics of the selected flexible material.

According to a further embodiment of this invention there is provided a tension wrench comprising a grip on the flexible arm or handle to ensure the maximum torque the arm or handle can transmit before flexing is not altered by the position of the user's hand on the arm or handle.

According to a further embodiment of this invention a variant is produced by a tension wrench locating one hand grip more or less mid-way along the flexible arm or handle and another more or less at the end of the arm or handle, producing two available torque capabilities from the one arm or handle depending on where it is grasped.

According to a further embodiment of this invention a method exists whereby a metal S. 20 spanner head, or any desired head, can be attached to the flexible arm or handle so as to om permit different spanner heads to be used with different tensioning handles.

oo- According to a further embodiment of this invention the spanner head or any desired 06 head of metal or other desired material is permanently joined to the flexible arm or handle oP° of polypropylene or other desired material.

S 25 According to a further embodiment of this invention the material polypropylene is used for the manufacture of the flexible arm or handles and the polypropylene is pre-flexed before delivery to stabilise the flexure or resistance to lexure.

o Brief Description of Drawings :Figure 1 is a perspective view of a first embodiment of a tension wrench according to 30 the present invention; S•Figure 2 is a perspective view of a second embodiment of a tension wrench according to the present invention; and Figure 3 is a perspective view of a third embodiment of a tension wrench according to the present invention.

[R:\l1.BZZJ06476.doc:NJC Description of Drawings In Figure 1 of the drawings, there is shown a first embodiment of this invention comprising a torque wrench (10) having a first end (12) and a second end An integrally formed terminal formed hand grip (16) is located at the first end (12) whilst a Srigid spanner head (18) is located at the second end A flexible arm member extends from the first end (12) to the second end (14) of the torque wrench The flexible arm member (20) is made of flexible material of calculated thickness and length and includes the terminal hand grip to produce a single preset measure of torque. Provision is also shown to couple a range of spanner heads to the arm or handle I In Figure 2 of the drawings, there is shown a second embodiment of the invention comprising a torque wrench (10) which is similar to the first embodiment of this invention and accordingly the same reference numerals are used to denote previously described integers of the torque wrench. The torque wrench of the second embodiment further comprises a second hand grip (22) located at a mid point along the flexible arm member i In Figure 3 of the drawings, there is shown a third embodiment of this invention comprising a torque wrench (10) similar to the second embodiment of this invention except that the spanner head (18) is formed integrally with the flexible arm member 0Figure 2 shows an improved torque wrench arm handle (20) made of flexible material of calculated thickness and length and including a terminal handle grip (16) and an intermediate handle grip to produce two preset measures of torque. Provision is shown to couple a range of spanner heads to the handle but no claim is made for this attachment method.

Figure 3 shows improved torque wrenches with integral heads that are permanently joined to the flexible handle.

Best mode for carrying out the invention Single torque flexible handles with fixed spanner heads or any other heads would be used in a corresponding manner to a regular spanner by tradespeople or assembly workers performing a repetition tightening function. An example would be an installer of electric ;o hand dryers with porcelain cases: the nut is always the same and the optimal tension before cracking the porcelain covers is constant.

Flexible handles with intermediate and terminal handgrips and a fixed spanner head -\Awi)d be used where two levels of torque are required for a constant size or type of nut or sinmlta-device requiring tightening.

I R:\iJ 13ZZ106476.doc:NJC One or more single torque or double torque handles would be used with a range of detachable spanner heads or other heads where a wide choice of heads and torque capabilities is required. Typically such combinations would be carried as a set with the head and handle selected for the application by the user.

Modifications and variations such as would be apparent to a skilled address are deemed to be within the scope of this invention. It is to be understood that this invention should not be restricted to the particular embodiment(s) described above.

o* o 9@ o a.* a a a a a.

a.i a.* a *~a a a.* [R:\LIBZZ]06476.doc:NJC

Claims (5)

1. 2. A tension wrench or spanner according to claim 1 wherein the wrench or spanner head is connected to a first end of the flexible arm or handle which is opposed to the hand grip which is located at a second end of the flexible arm or handle.
2. 3. A tension wrench or spanner according to claim 1 or 2 wherein the wrench or spanner head is integrally formed with the flexible arm or handle.
3. 4. A tension wrench or spanner according to claim 1 or 2 wherein the spanner head is detachably found attached with the flexible arm or handle. A tension wrench or spanner according to any one of the preceding claims wherein the flexible arm or handle has a first hand grip located at one end and a second hand grip located towards the centre of the flexible arm or handle.
4. 6. A tension wrench or spanner according to any one of the preceding claims wherein the wrench or spanner is made from a material that has been pre-stressed or pre- "I flexed to stabilise flexure or resistance to within predetermined torque values. 20 7. A tension wrench or spanner according to claim 6 wherein the material is polypropylene.
5. 8. A tension wrench substantially as hereinbefore described with reference to the a accompanying drawings. S9. A method of tightening a nut, bolt or the like using a tension wrench or spanner S: 25 according to any one of claims 1 to 8. w :t10. A method of tightening a nut, bolt or like substantially as hereinbefore described r with reference to the accompanying drawings. Dated 20 December, 1999 oee Haddon/Perceptions Pty. Ltd. oo e Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON LR:\LI BZZ]06476.doc:NJC