GB2138912A - Locking tab washer - Google Patents

Abstract

A locking tab washer has a downwardly turned tab (17) and a pair of upwardly turned tabs (15) with lips (16). In use the upwardly turned tabs are impacted with a tool (Figure 2, not shown) having an approximately semi-circular lip which bends the tabs (15) towards the nut (13) to be locked so that at least one lip (16) engages a face of the nut to effect locking. <IMAGE>

Description

SPECIFICATION Locking tab washer This invention relates to tab washers for locking nuts and screws.

The invention can be used to lock loose and fully tightened nuts in position. Compared with the stan dard known tab washer (BPS/SP 41-46) it is well suited for use in locations difficult of access and can be brought into use with remote handling tools. This is achieved byarrangingforthetabwasherto betaken to the locking position by axial impact. Applied lever action from a radial direction is avoided. Thus tab washers according to the invention are well suited to locking nuts in recesses where a customary lever action could not be applied. Locking is by a mechanic al engagement and does not rely on frictional devices.

Locking can be performed by a remotely operated pneumatic hammer and is therefore suitable for use within the nuclear industry, on machinery that re quires remote maintenance within caves, by power manipulators.

Locking operations are preferably carried out with an impacting tool which, for a specific nut size, requires only slightly more space for access than that required by a socket for tightening the nut. Release of a locked nut can also be performed with a tool not requiring more space for access than that already provided fortightening and locking.

Oneform of locking tab washer according to the present invention will now be described with refer ence to the accompanying drawings in which: Figures 1 A-D show various stages in tightening a nut to a bolt and locking it by the tab washer; Figure 2 shows in perspective, partly broken away, the locking tool usable to deform the tab washer to the locking position; Figure 3 shows, in perspective, one form of the locking washer; and Figure 4 shows in perspective a locked nut.

In Figures 1 A-D there is shown a stud 10 which terminates in a cavity 11 in a body 12. The stud 10 has fitted to it a nut 13 and washer 14. The washer (Fig. 3) has a pair of upstanding tabs 15 with lips 16 and a downturn tab 17.

In Figure 1Athe nut 13 is shown engaged by a tightening socket 20; in Figure 1 B the socket 20 has been removed and replaced with an impact locking tool 21 (see also Figure 2); in Figure 1Cthetool 21 has been partly depressed to completeafirstforming action on the tabs 15; and in Figure 1 D thetool 21 has been fully depressed to complete the locking action on the tabs 15.

In Figure 2thetool 21 is shown as having a body 22, an approximately semi-circular lip 23, and two flats 24.

In use the washer 14 is applied over the stud 10 so thatthe downturn tab 17 engages a location hole 25 in the body 12. The nut 13 is then tightened with a socket.

The socket is removed and replaced with the tool 21 (Figure 1 B). The tool is impacted to deform the tabs 15 onto the nut 13 (Figure 1C) and then bend the lips 16 (Figure 1 D) so the lips a but the nut and thereby lockthe nut in position.The locked nut is shown in Figure 4.

The angle between the tabs is designed to ensure that at least one tab ends up against a flat of the nut.

To unlockthe nut 13, the nut 13 can be turned to twistthetabs 15 away from their locking position our a furthertool can be used to impactthetabs 15 into a flattened state.

Thewasher 14 may have morethantwotabsorthe tabs may have locations otherthanthose shown in the drawings.

The use of tab washers according to the invention does not require alteration or modification to standard bolts, nuts and sockets.

1. A locking tab washer having an upstanding lipped tab disposed so that, in use to lock a nut in position, thetab can be bent towards a face of the nut and the lip then engages said face to effect locking.

2. A locking tabwasher having a pair of upstanding lipped tabs and a downwardlyformed tab disposed so that, in use to iocka nut in position, the lipped tabs can be benttowards the nut so that one lip engages a face on the nut and, with the downwardly formed tab engaged in a location hole, locking ofthe nut is effected.

3. A locking tab washer substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

4. Atabwasher nut locking kit comprising locking tab washers as claimed in any preceding claim and an impact locking tool for the washers substantially as hereinbefore described with reference to Figure 2 of the drawings.

5. A method of locking a nut to a stud or bolt comprising applying a locking tab washer as claimed in any one of claims 1 to 3 to the stud or bolt, tightening the nut, and impacting the lipped tabs with a tool having a lip which engages said tabsto bend them towards the nut.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Locking tab washer This invention relates to tab washers for locking nuts and screws. The invention can be used to lock loose and fully tightened nuts in position. Compared with the stan dard known tab washer (BPS/SP 41-46) it is well suited for use in locations difficult of access and can be brought into use with remote handling tools. This is achieved byarrangingforthetabwasherto betaken to the locking position by axial impact. Applied lever action from a radial direction is avoided. Thus tab washers according to the invention are well suited to locking nuts in recesses where a customary lever action could not be applied. Locking is by a mechanic al engagement and does not rely on frictional devices. Locking can be performed by a remotely operated pneumatic hammer and is therefore suitable for use within the nuclear industry, on machinery that re quires remote maintenance within caves, by power manipulators. Locking operations are preferably carried out with an impacting tool which, for a specific nut size, requires only slightly more space for access than that required by a socket for tightening the nut. Release of a locked nut can also be performed with a tool not requiring more space for access than that already provided fortightening and locking. Oneform of locking tab washer according to the present invention will now be described with refer ence to the accompanying drawings in which: Figures 1 A-D show various stages in tightening a nut to a bolt and locking it by the tab washer; Figure 2 shows in perspective, partly broken away, the locking tool usable to deform the tab washer to the locking position; Figure 3 shows, in perspective, one form of the locking washer; and Figure 4 shows in perspective a locked nut. In Figures 1 A-D there is shown a stud 10 which terminates in a cavity 11 in a body 12. The stud 10 has fitted to it a nut 13 and washer 14. The washer (Fig. 3) has a pair of upstanding tabs 15 with lips 16 and a downturn tab 17. In Figure 1Athe nut 13 is shown engaged by a tightening socket 20; in Figure 1 B the socket 20 has been removed and replaced with an impact locking tool 21 (see also Figure 2); in Figure 1Cthetool 21 has been partly depressed to completeafirstforming action on the tabs 15; and in Figure 1 D thetool 21 has been fully depressed to complete the locking action on the tabs 15. In Figure 2thetool 21 is shown as having a body 22, an approximately semi-circular lip 23, and two flats 24. In use the washer 14 is applied over the stud 10 so thatthe downturn tab 17 engages a location hole 25 in the body 12. The nut 13 is then tightened with a socket. The socket is removed and replaced with the tool 21 (Figure 1 B). The tool is impacted to deform the tabs 15 onto the nut 13 (Figure 1C) and then bend the lips 16 (Figure 1 D) so the lips a but the nut and thereby lockthe nut in position.The locked nut is shown in Figure 4. The angle between the tabs is designed to ensure that at least one tab ends up against a flat of the nut. To unlockthe nut 13, the nut 13 can be turned to twistthetabs 15 away from their locking position our a furthertool can be used to impactthetabs 15 into a flattened state. Thewasher 14 may have morethantwotabsorthe tabs may have locations otherthanthose shown in the drawings. The use of tab washers according to the invention does not require alteration or modification to standard bolts, nuts and sockets. CLAIMS

1. A locking tab washer having an upstanding lipped tab disposed so that, in use to lock a nut in position, thetab can be bent towards a face of the nut and the lip then engages said face to effect locking.

2. A locking tabwasher having a pair of upstanding lipped tabs and a downwardlyformed tab disposed so that, in use to iocka nut in position, the lipped tabs can be benttowards the nut so that one lip engages a face on the nut and, with the downwardly formed tab engaged in a location hole, locking ofthe nut is effected.

3. A locking tab washer substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

4. Atabwasher nut locking kit comprising locking tab washers as claimed in any preceding claim and an impact locking tool for the washers substantially as hereinbefore described with reference to Figure 2 of the drawings.

5. A method of locking a nut to a stud or bolt comprising applying a locking tab washer as claimed in any one of claims 1 to 3 to the stud or bolt, tightening the nut, and impacting the lipped tabs with a tool having a lip which engages said tabsto bend them towards the nut.