Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
STRAP WRENCH
Document Type and Number:
WIPO Patent Application WO/2005/014230
Kind Code:
A1
Abstract:
A strap wrench comprises a handle and a strap, the handle having a channel formed therein for receiving the strap, wherein the strap forms a loop at an end of the handle, the strap having a first enlarged head on a first side of the loop, the first enlarged head being received in a portion of the channel, and wherein a portion of the strap on a second side of the loop is slidably retained by the first enlarged head.

More Like This:
Inventors:
PRIESTMAN PAUL (GB)
Application Number:
PCT/GB2004/002896
Publication Date:
February 17, 2005
Filing Date:
July 06, 2004
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
BOA UK LTD (GB)
PRIESTMAN PAUL (GB)
International Classes:
B25B13/52; (IPC1-7): B25B13/52
Foreign References:
GB2351688A2001-01-10
US2132207A1938-10-04
GB2202478A1988-09-28
DE8613609U11986-07-31
Attorney, Agent or Firm:
ELKINGTON AND FIFE LLP (8 Pembroke Road Sevenoaks, Kent TN13 1XR, GB)
Download PDF:
Claims:
CLAIMS :
1. A strap wrench comprising a handle and a strap, the handle having a channel formed therein for receiving the strap, wherein the strap forms a loop at an end of the handle, the strap having a first enlarged head on a first side of the loop, the first enlarged head being received in a portion of the channel, and wherein a portion of the strap on a second side of the loop is slidably retained by the first enlarged head.
2. The strap wrench of claim 1, wherein the first enlarged head is at a first end of the strap.
3. The strap wrench of claim 1 or 2, wherein the strap has a second enlarged head on the second side of the loop.
4. The strap wrench of any one of the preceding claims, wherein the second enlarged head is at a second end of the strap.
5. The strap wrench of any one of the preceding claims, wherein the first enlarged head has a channel formed therein for receiving the portion of the strap on the second side of the loop.
6. The strap wrench of any one of the preceding claims, wherein the outer periphery of the first enlarged head is substantially cylindrical.
7. The strap wrench of any one of the preceding claims, wherein the handle is produced by a moulding or casting process.
Description:
STRAP WRENCH This invention relates to strap wrenches.

Strap wrenches are well known devices that are useful in a number of applications where there is a requirement for a large torque to be applied in order to rotate a cylindrical member. For example, strap wrenches may be used to release screw caps from storage vessels or to remove oil filter assemblies from engines.

A known strap wrench is shown in figure 1. The strap wrench 1 comprises a rigid elongate handle 3 and a flexible strap 5. A first end 5a of the flexible strap 5 is fixed to a first end 3a of the handle 3. A second end 5b of the flexible strap 5 is movable relative to the handle 3. In use, a portion of the flexible strap 5 near the first end 3a of the handle 3 is formed into a loop. The remainder of the flexible strap 5 is inserted into a guide channel 7 formed within the handle 3. The loop is placed around the cylindrical member to be rotated and the flexible strap 5 is then tightened around the cylindrical member by sliding the flexible strap 5 through the guide channel 7. A torque is applied to the cylindrical member by applying a lateral force against the second end 3b of the handle 3 in the direction of arrow 9. This lateral force causes the handle 3 to pivot about its first end 3a. This pivoting movement tightens the flexible strap 5 around the cylindrical member. Eventually, the cylindrical member rotates with the strap wrench 1.

Depending upon the shape of the first end 3a of the handle 3, a large torque can be applied to the cylindrical member by applying a relatively small force on the second end 3b of the handle 3. Strap wrenches are therefore of particular benefit to older people or people suffering from arthritis because they reduce the effort required to remove screw caps.

The handle of a strap wrench is normally produced using a moulding or a casting process in order to provide the complex functional features and

aesthetic shape required. Strap wrench handles may therefore be formed from plastics, metals, or any other material that can be formed into complex shapes.

Surface treatments such as. paints are also frequently applied to the handles.

The strap wrench of figure 1 is constructed so that only one end of the flexible strap is fixed to the handle. The other end of the flexible strap is not fixed, and is free to move relative to the handle. In use, the flexible strap has to be formed into a loop and the free end has to be inserted into the guide channel within the handle. The flexible strap can easily fall out of the channel after the strap wrench has been used.

A problem with these known strap wrenches is that each time the strap wrench is to be used, the flexible strap must first be formed into a loop and often the free end of the flexible strap must be inserted into the guide channel within the handle. This can be time consuming and awkward because the flexible strap may be very long in order to accommodate a variety of sizes of cylindrical members.

The above problem cannot easily be overcome by making changes to the shape of the handle because of limitations in the moulding or casting process. In particular, it would not be possible to release the necessary handle shape from a mould or cast.

According to the invention, there is provided a strap wrench comprising a handle and a flexible strap, the handle having a channel formed therein for receiving the strap, wherein the strap forms a loop at an end of the handle, the strap having a first enlarged head on a first side of the loop, the first enlarged head being received in a portion of the channel, and wherein a portion of the strap on a second side of the loop is slidably retained by the first enlarged head.

In the strap wrench of the invention, the free end of the flexible strap is slidably retained in the guide channel within the handle by an enlarged head

formed at the other end of the flexible strap. In this way, the free end of the flexible strap can be retained in the guide channel of a moulded or cast handle without any"undercuts"being required in the handle mould or cast.

Preferably the first enlarged head is at a first end of the strap.

Preferably, the strap has a second enlarged head on the second side of the loop. The second enlarged head prevents disengagement of the portion'of the strap on the second side of the loop. In this way, the maximum extent to which the free end of the flexible strap may slide is limited.

Preferably the second enlarged head is at a second end of the strap.

Preferably, the first enlarged head has a channel formed therein for receiving the portion of the strap on the second side of the loop.

Preferably, the outer periphery of the first enlarged head is substantially cylindrical.

Preferably, the handle is produced by a moulding or casting process.

Such processes are capable of providing a handle having the necessary functional features and aesthetic shape.

The invention will now be described by way of example with reference to the following figures in which: Figure 1 is a plan view of a known strap wrench; Figure 2 is a plan view of a strap wrench according to the invention; Figure 3a is a perspective view of a first enlarged head of a flexible strap of the strap wrench according to the invention; and

Figure 3b is a perspective view of a second enlarged head of a flexible strap of the strap wrench according to the invention.

Referring to figure 2, a strap wrench 101 according to the invention comprises a handle 103 and a flexible strap 105. A guide channel 107 is formed within the handle 103 for receiving the flexible strap 105.

A first end 105a of the flexible strap 105 is terminated in a first enlarged head 111 and a second end 105b of the flexible strap 105 is terminated in a second enlarged head 113. The first and second enlarged heads 111,113 are shown in figures 3A and 3B respectively.

Referring to figure 3A, the outer periphery of the first enlarged head 111 is cylindrical. However, the first enlarged head 111 also has a large, substantially semi-cylindrical, cut out 115. The resulting shape of the first enlarged head 111 provides a pair of parallel flanges 111 a, 111 b.

Referring to figure 3B, the width of the second enlarged head 113 is greater than the width of the rest of the flexible strap 105 (apart from the first enlarged head 111). The width of the second enlarged head 113 is also larger than the distance between the opposing surfaces of the flanges 111 a, 111b of the first enlarged head 111. The second enlarged head 113 can act as a grip when initially tightening the loop around the cylindrical member.

The strap wrench 101 is assembled as follows. The flexible strap 105 is formed into a loop so that the first enlarged head 111 is on a first side of the loop. A portion of the flexible strap 105 on a second side of the loop is inserted between flanges 111 a, 111 b into the cut out 115 in the first enlarged head 111.

With the portion of the flexible strap 105 still inserted into the cut out 115 in the first enlarged head, the flexible strap 105 is received into the guide channel 107. In particular, the first enlarged head 111 of the flexible strap 105 is received into a portion 107a of the guide channel 107, thus securely fixing the first end 105a of the flexible strap 105 near to the first end 103a of the handle

103. The portion of the flexible strap 105 on the second side of the loop is received into the guide channel 107 and is slidable within the guide channel.

The first enlarged-head 111 is a friction fit into the. portion 107a of the guide channel 107 so that the flexible strap 105 cannot fall out.

In the assembled strap wrench 101 of the invention, the portion of the flexible strap 105 on the second side of the loop is slidably retained such that it cannot be removed from the guide channel. In particular, the flexible strap 105 is trapped in the cut out 115, to prevent escape from the guide channel 107 laterally (i. e. upwardly with respect to the orientation shown in figure 2). Also, the flexible strap 105 cannot be slid longitudinally out of the guide channel 107 because the second enlarged head 113 at the second end 105b of. the flexible strap 105 is too large to pass between the flanges 111a, 111b of the first enlarged head 111.

The strap wrench 101 of the invention is used in a similar way to the known strap wrench 1 of figure 1. However, the need to form the flexible strap 105 into a loop and insert its free end into guide channel 107 is eliminated once the strap wrench 101 has been initially assembled.

Accordingly, the already formed loop of the assembled strap wrench 101 is placed around the cylindrical member to be rotated. The flexible strap 105 is then tightened around the cylindrical member by pulling the flexible strap 105 through the guide channel 107. A torque is applied to the cylindrical member by applying a lateral force against the second end 103b of the handle 103 in the direction of arrow 109.

The strap wrench of the invention may be used more quickly and easily than the known strap wrench of figure 1. Furthermore, the handle of the strap wrench of the invention may still be produced by moulding or casting processes because the free end of the flexible strap is retained by features of the strap in combination with the handle, and not just features of the handle.

The strap wrench of the invention is described by way of example only.

In other strap wrenches of the invention, the shapes of the first and second enlarged heads 111,113 may be different. For example, the outer periphery of the first enlarged head 111 may be cubic, and the body of the first enlarged head 111 may have a through hole instead of a cut out 115.

The base of the portion 107a of the guide channel 107 may be solid, so that the first enlarged head 111 only needs a top flange 111 a to retain the strap 105 laterally. The base of the portion 107a of the guide channel 107 can thus perform the function of the second flange 111 b.

In figure 2, the guide channel 107 has a"Y"shape. However, the first enlarged head 111 may be received into the guide channel 107 nearer to the end 103a of the handle 103, and the guide channel 107 may then have only one limb on each side of the portion 107a. Also, the flexible strap 105 does not need to run the full length of the handle 103.

Various other modifications will be apparent to those skilled in the art.