GB2031314A - Strap wrench for gripping cylindrical articles - Google Patents

Abstract

A strap wrench for gripping cylindrical articles 16 such as motor vehicle oil filter casings comprises a substantially circular disc 1 with rotary coupling means such as an axial non- circular (e.g. square or hexagonal) hole 2, recess or projection or a transverse slot or rib, for receiving a tool such as a socket bar by means of which it may be rotated, a flexible strap 4, and a link 5 pivotally joining the strap end to the disc adjacent to the periphery thereof and providing an opening through which the free end 4a of the strap may be passed so that when the strap is in position around the cylindrical article, and the disc is turned, the free end of the strap is gripped between the peripheral surface of the disc and the outer end of the link and the strap is tightened by rolling of the disc with respect to the periphery of the cylindrical article. <IMAGE>

Description

SPECIFICATION Wrench for gripping cylindrical articles This invention relates to wrenches for gripping cylindrical articles. It has been particularly developed for screwing up and unscrewing oil filter casings on internal combustion engines but it is not limited to this technical application. It could for example be used for screwing up or unscrewing gas pipes.

Chain wrenches are currently used for removing oil filter casings but as they are liable to damage the casings, they cannot be employed for removing reusable casings nor for tightening casings. Furthermore such chain wrenches need preliminary adjustment to suit the casing.

In accordance with this invention, we provide a strap wrench for gripping cylindrical articles comprising a circular disc (or wheel) with rotary coupling means such as an axial non-circular (e.g.

square or hexagonal) hole, recess or projection or a transverse slot or rib, for receiving a tool by means of which it may be rotated, a flexible strap, and a link pivotally joining the strap to the disc adjacent to the periphery thereof and providing an opening through which the free end of the strap may be passed so that when the strap is in position around the cylindrical article, and the disc is turned, the free end of the strap is gripped between the peripheral surface of the disc and the outer end of the link and the strap is tightened by rolling of the disc with respect to the periphery of the cylindrical article.

An embodiment of the invention will now be described by way of example with reference to the drawing in which the sole figure is a plan view of a wrench in an operative position for removing an oil filter casing.

A circular disc 1 is formed as a plastics moulding, e.g., of nylon, and has a square central hole 2 and axially-extending serrations 3 around its periphery. In the illustrated embodiment, the disc 1 has a diameter of 4.2 cm and a thickness of 1.3 cm. A strap 4 of webbing or plastics material of approximately the same width as the thickness of the disc 1 is connected to the disc 1 by a link 5 which is also of plastics material and which is similar to a roller chain link. It has plates 8 (only one shown) one above the other, pins 9, 10 on the lower plate passing through corresponding holes in the upper plate and being secured by a spring clip in the usual way. Pin 9 passes through a hole 11 in the disc 1 and pin 10 passes through a loop 12 in the end of the strap, the loop 12 being formed by any suitable means such as stitching, welding or rivetting.The link 5 thus provides an opening 14 through which the free end 1 5 of the strap 4 may be passed.

In operation the strap 4 is placed around the filter casing 1 6 and the free end 4a is passed through the link 5. Alternatively if convenient, a loop in the strap is dropped over the casing 16.

The end of a socket bar (not shown) has meanwhile been placed in the hole 2 (preferably with a snug fitting ora suitable detent ball to prevent inadvertent separation) and this is now rotated anticlockwise to unscrew the casing 16, e.g., with a ratchet handle. It will be seen that the strap is gripped between the disc 1 and the outer end of the link 5. If there is some initial slippage the disc rotates thus making the grip more effective by forcing a greater length f?f strap onto the serrations. The operation has the great advantage of being self-adjusting because the grip increases the more the disc is rotated. thus there is no need for a preliminary critical adjustment of the amount of strap in the loop passing around the casing 1 6 as would be the case with a conventional strap wrench.Furthermore the wrench is reversible in that the casing 16 can be screwed up simply by turning the socket bar in a clockwise direction without adjusting the strap.

In a modification (not shown), the strap is of plastics material and has teeth which match the serrations on the disc.

Desirably, the strap has a roughened surface for gripping the filter casing.

It will be appreciated that a standard socket wrench set will have extension bars of different lengths and these can be selected to give a convenient position for the handle (in the case of an oil filter this will usually be beyond the end of the filter). It has been found that a one armed handle is surprisingly sufficiently stable to unscrew an oil filter though it is desirable that the assembly is steadied by hand at the pivot axis. A T-handle can of course be used if desired.

Another feature of the preferred construction is that the strap is sufficiently resistant to sideways deformation than the disc rolls along the strap without dropping below it.

An advantage of a non-metal wrench is that the danger of sparks is reduced or eliminated; this has particular importance when handiing gas fittings.

1. A strap wrench for gripping cylindrical articles comprising a substantially circular disc with rotary coupling means for receiving a tool by means of which it may be rotated, a flexible strap, and a link pivotallyjoining the strap to the disc adjacent to the periphery thereof and providing an opening through which the free end of the strap may be passed so that when the strap is in position around the cylindrical article, and the disc is turned, the free end of the strap is gripped between the peripheral surface of the disc and the outer end of the link and the strap is tightened by rolling of the disc with respect to the periphery of the cylindrical article.

2. A wrench according to claim 1 , wherein the peripheral surface is serrated to increase its ability to grip the strap.

3. A wrench according to claim 1 or 2, wherein the member is a plastics moulding.

4. A wrench according to any preceding claim, wherein the rotary coupling means is a square hole or recess which is of a size to receive a standard socket bar.

5. A wrench according to any preceding claim,

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Wrench for gripping cylindrical articles This invention relates to wrenches for gripping cylindrical articles. It has been particularly developed for screwing up and unscrewing oil filter casings on internal combustion engines but it is not limited to this technical application. It could for example be used for screwing up or unscrewing gas pipes. Chain wrenches are currently used for removing oil filter casings but as they are liable to damage the casings, they cannot be employed for removing reusable casings nor for tightening casings. Furthermore such chain wrenches need preliminary adjustment to suit the casing. In accordance with this invention, we provide a strap wrench for gripping cylindrical articles comprising a circular disc (or wheel) with rotary coupling means such as an axial non-circular (e.g. square or hexagonal) hole, recess or projection or a transverse slot or rib, for receiving a tool by means of which it may be rotated, a flexible strap, and a link pivotally joining the strap to the disc adjacent to the periphery thereof and providing an opening through which the free end of the strap may be passed so that when the strap is in position around the cylindrical article, and the disc is turned, the free end of the strap is gripped between the peripheral surface of the disc and the outer end of the link and the strap is tightened by rolling of the disc with respect to the periphery of the cylindrical article. An embodiment of the invention will now be described by way of example with reference to the drawing in which the sole figure is a plan view of a wrench in an operative position for removing an oil filter casing. A circular disc 1 is formed as a plastics moulding, e.g., of nylon, and has a square central hole 2 and axially-extending serrations 3 around its periphery. In the illustrated embodiment, the disc 1 has a diameter of 4.2 cm and a thickness of 1.3 cm. A strap 4 of webbing or plastics material of approximately the same width as the thickness of the disc 1 is connected to the disc 1 by a link 5 which is also of plastics material and which is similar to a roller chain link. It has plates 8 (only one shown) one above the other, pins 9, 10 on the lower plate passing through corresponding holes in the upper plate and being secured by a spring clip in the usual way. Pin 9 passes through a hole 11 in the disc 1 and pin 10 passes through a loop 12 in the end of the strap, the loop 12 being formed by any suitable means such as stitching, welding or rivetting.The link 5 thus provides an opening 14 through which the free end 1 5 of the strap 4 may be passed. In operation the strap 4 is placed around the filter casing 1 6 and the free end 4a is passed through the link 5. Alternatively if convenient, a loop in the strap is dropped over the casing 16. The end of a socket bar (not shown) has meanwhile been placed in the hole 2 (preferably with a snug fitting ora suitable detent ball to prevent inadvertent separation) and this is now rotated anticlockwise to unscrew the casing 16, e.g., with a ratchet handle. It will be seen that the strap is gripped between the disc 1 and the outer end of the link 5. If there is some initial slippage the disc rotates thus making the grip more effective by forcing a greater length f?f strap onto the serrations. The operation has the great advantage of being self-adjusting because the grip increases the more the disc is rotated. thus there is no need for a preliminary critical adjustment of the amount of strap in the loop passing around the casing 1 6 as would be the case with a conventional strap wrench.Furthermore the wrench is reversible in that the casing 16 can be screwed up simply by turning the socket bar in a clockwise direction without adjusting the strap. In a modification (not shown), the strap is of plastics material and has teeth which match the serrations on the disc. Desirably, the strap has a roughened surface for gripping the filter casing. It will be appreciated that a standard socket wrench set will have extension bars of different lengths and these can be selected to give a convenient position for the handle (in the case of an oil filter this will usually be beyond the end of the filter). It has been found that a one armed handle is surprisingly sufficiently stable to unscrew an oil filter though it is desirable that the assembly is steadied by hand at the pivot axis. A T-handle can of course be used if desired. Another feature of the preferred construction is that the strap is sufficiently resistant to sideways deformation than the disc rolls along the strap without dropping below it. An advantage of a non-metal wrench is that the danger of sparks is reduced or eliminated; this has particular importance when handiing gas fittings. CLAIMS

1. A strap wrench for gripping cylindrical articles comprising a substantially circular disc with rotary coupling means for receiving a tool by means of which it may be rotated, a flexible strap, and a link pivotallyjoining the strap to the disc adjacent to the periphery thereof and providing an opening through which the free end of the strap may be passed so that when the strap is in position around the cylindrical article, and the disc is turned, the free end of the strap is gripped between the peripheral surface of the disc and the outer end of the link and the strap is tightened by rolling of the disc with respect to the periphery of the cylindrical article.

2. A wrench according to claim 1 , wherein the peripheral surface is serrated to increase its ability to grip the strap.

3. A wrench according to claim 1 or 2, wherein the member is a plastics moulding.

4. A wrench according to any preceding claim, wherein the rotary coupling means is a square hole or recess which is of a size to receive a standard socket bar.

5. A wrench according to any preceding claim, wherein the link lies at an angle of about 45 to a perpendicular from the peripheral surface of the disc when it is gripping the strap.

6. A wrench according to any preceding claim, wherein the link comprises two parallel plates joined by pins at their respective ends one pin passing through the disc and the other fastening the strap.

7. A wrench according to any preceding claim, wherein the link is of plastics material.

8. A strap wrench substantially as hereinbefore described with reference to the drawings.