GB1563811A - Locking element - Google Patents

Description

(54) IMPROVED LOCKING ELEMENT (71) 1, Jolis KENNETH WRIGHT, a British Subject, of Flaxmoss House, 71 St.

Annes Road East, St. Annes-on-Sea, FY8 IL'R, Lancashire, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention concerns an improved locking element. More particularly it relates to an improved form of locking bolt, locking stud or locking nut which is capable of providing a positive and reliable locking action.

Various means are known for locking a threaded bolt or stud and these include the use of a spring or locking washer encircling the shank of the bolt or stud and acting against a nut threaded thereon to force the thread within the nut into frictional engagement with the thread of the bolt or stud.

The washer when uncompressed has the form of a single helical turn which is so directed that in compression between an element such as the head, a shoulder or an abutment on the bolt or stud, and the nut, the washer bites into the nut whenever it exhibits a tendency to slacken, thus further locking the nut on the bolt or stud. It is also known to lock a bolt by means of two nuts whose internal threads frictionally engage the thread of the bolt, the nuts being in juxtaposition and acting against each other in order to maintain this engagement, One problem with known locking means is the tendency for the locking action to deteriorate when the bolt or stud and nut is subjected to vibration, and it is one aim of the present invention to provide a locking element which exhibits an improved locking action under such conditions.

According to the present invention, a locking element comprises two co-operating parts having mating threads enabling the parts to be relative rotatable and having respective matching threads with a pitch which differs from that of the mating threads, the parts by virtue of the difference in pitches being relatively rotatable from a position wherein the respective matching threads form an extension one of the other and are capable of receiving a complemen- tarily threaded member into a locking position wherein the respective matching threads do not form an extension one of the other for locking the respective matching threads against respective thread portions of the complementarily threaded member.

It is possible for the locking element to include resilient means, such as a spring washer, urging the parts toward their locking position but permitting relative displacement of the parts from their locking position into their initial position for releasing said complementarily threaded member.

Another possibility is to provide the parts with a stop which snaps into place as the parts move into their locking position and which is arranged to prevent further relative movement of the parts, in use, and thus to prevent unlocking. For example, the stop may comprise a C-clip initially supported in tension on respective opposed shoulders on each of the two parts and arranged to snap into a relaxed condition between the shoulders as the parts are moved into their locking position.

The invention may be applied to various members. One such member is a locking bolt wherein the component parts are telescoped together, the free end of one part having a head and the free end of the other part containing a key way. In this instance relative movement of the two parts is achieved by engaging the head and the key way with suitable implements and rotating one part relative to the other, and the bridging member comprises a nut fitted over the two parts.

Another such member is a stud again hav ing the two parts telescoped together, one part being provided with an extension, which extends right through the other part to a headed end thereof and whose end contains a keyway. This allows locking to be achieved when the stud is inserted into a blind hole.

It is equally possible, however, for the invention to be applied to a nut whose component parts comprise a frst nut portion having a hollow internally threaded extension and a second nut portion having a stepped bore which receives the extension on the first portion. Such a nut may be fitted on a conventional bolt or stud.

The invention will be described further, by way of example, with reference to the accompanying drawings in which :- Fig. I is a side view of a locking nut in its initial position and mounted on a bolt or ; Fig. 2 is a side view of the same with the nut in its locking position ; Fig. 3 is a side view of a second locking nut in its initial position and mounted on a bolt or ; Fig. 4 is a side view of the second nut in its locking position on the bolt or stud; Fig. 5 is a longitudinal section through a locking bolt ; and Fig. 6 is a longitudinal section through a locking stud; Fig. 7 is a partial section through a locking element for controlling a valve; Fig. 8 is a partial section through another valve control locking element; and Fig. 9 is a partial section through a locking element for controlling a clutch rod or hand brake cable.

In Fig. 1 a bolt or stud 10 is shown projecting from a member 12. Fitted over the bolt or stud 10 is a second member 14 which is held against the member 12 by means of a locking nut 16 threaded onto the bolt or stud 10 and a washer 18 lying between the member 14 and the nut 16.

The locking nut 16 itself comprises two co-operating parts 20,22, the part 20 having a tubular extension 24 which is received in the enlarged portion 26 of a stepped bore 28 in the part 22. The part 20 has an internal thread 30 matching an internal thread 32 in the smaller portion of the bore 28 and when the nut is in the position shown in Fig. 1, these threads are arranged so as to form a continuation one of the other. The enlarged portion 26. of the bore 28 is also provided with a thread 34 which engages an external thread 36 on the extention 24, these two threads having a pitch which differs from that of the two matching threads 30, 32.

Located between the nut parts 20,22, each of which has an hexagonal outer surface, is a spring washer 38. In its fully compressed state, as shown in Fig. 1, this washer is O-shaped but when it is uncompressed or only partially compressed, it forms a single helical turn which is so directed that the washer tends to bite into the surfaces of the two parts should they be tightened together.

In order to mount the nut on a bolt or stud, its parts are fully tightened together to the position shown in Fig. I wherein the extension 24 extends approximately half way through the part 2, the matching threads are aligned and the spring washer is fully compressed. When it is desired to lock the nut on the bolt or stud, the part 22 is unscrewed from the part 20 until it can be unscrewed no further. This causes the nut to become locked on the bolt or stud because the pitch of the matching threads is different from that of the threads on the mating nut portions.

The nut is shown in its locking position in Fig. 2, the spring washer 38 still being partially compressed. If vibration occurs while the nut is in this position, the parts 20,22 tend to separate under the action of the spring washer. However this results in an increased locking action.

If it is desired to release the locking action, the part. 22 is merely tightened on the part 20 thus forcing the washer 38 into its fully compressed state.

If, on the other hand, a permanent locking action is required, the locking nut 50 shown in Figs. 3 and 4 may be used. This nut is similar to that of Figs. 1 and 2 except in that the nut parts 52,54 are provided with respective annular shoulders 56, 58 located on adjacent surfaces of the parts 52,54. An expanded C-shaped washer or C-clip 60 is seated on the two shoulders 56, 58 when the nut parts are in their initial position shown in Fig. 3. However, when the parts are displaced relative to each other into their locking position shown in Fig. 4, the shoulders move apart and the clip 60 springs into the gap between the shoulders, aided by the fact that the shoulders are slightly chamfered. This effec tively locks the nut permanently on the bolt or stud since the clip cannot easily be removed once it has snapped into place between the shoulders 56, 58.

The principal behind the locking bolt 80 shown in Fig. 5 is the same as that underlying the nuts of Figs. I to 4. The bolt has two co-operating component parts in the form of a body portion 82 and an end portion 84 which is movable relative to the body portion 82.

One end of the body portion 82 is formed into a hexagonal head 86, the other end containing a threaded bore 88. A threaded extension 90 on the end portion 84 mates with the bore 88 of the body por tion 82 and a spring washer 92 is received on the extension 90 between the end and body portions 84, 82. The free end of the end portion 84 contains a hexagonal keyway 94 suitable for receiving an Allen key.

Both the portions have external threads 96,98 which match each other, whose pitch differs from that of the mating threads, and which are aligned when the portions are in their initial position, the end portion 84 then being screwed up against the body portion 82 so that the spring washer is fully compressed. In this position a nut 99 of approximately two thirds of the depth of an equivalent conventional nut in combination with a conventional locking nut, can be threaded onto the end portion, which has three or four thread turns, across the gap between the two portions and onto the body portion. When the nut has been tightened on the bolt and providing that it then bridges the two component parts, the bolt is locked by inserting an Allen key in the keyway 94 and rotating or unscrewing the end portion 84 relative to the body portion 82.

As in the case of the nut, the locking action is achieved by virtue of the fact that the pitches of the external threads and of the mating threads do not coincide. And again the use of the spring washer allows the locking bolt to be released subsequently.

However, is a permanent locking action is required, an arrangement similar to that shown in Figs. 3 and 4 and employing a C-clip can be provided on the bolt.

In Fig. 6, the bolt of Fig. 5 has been modified to provide a stud 100 which can be inserted into a blind hole. The stud is the same as the bolt except that movement of the end portion 84 is controlled from the head 102 of the stud, the body portion 82 of the stud having a through bore 104 and the extension 106 on the end portion 84 extending right through the body portion to the head where it is provided with a keyway 108. However, only a section of the bore, and a corresponding section of the extension, is threaded, this section being located adjacent the end portion 84 of the stud. As before the pitch of the mating threads differs from that of the matching threads so that locking takes place when the portions 82, 84 are displaced relative to each other.

Referring to Fig. 7, a further locking element 110 is illustrated for use in controlling a valve (not shown). The element 110 has two co-operating parts 112, 114, the part 112 being fixed relative to a valve body (not shown) and containing a stepped bore 116. The enlarged region of the stenped bore 116 has a thread which mates with an external thread on a tubular body 118 of the part 114, and an annular shoulder 120 define between the larger and the smaller region of the bore 116 serves as a seat for a spring 122 which acts against an end face of the body 118. Both the smaller region of the bore 116 and the interior of the body 118 have matching threads and receive a threaded bolt 124 which bridges the parts 112,114 and which is connected to a valve closure member (not shown).

The thread within the enlarged region of the bore 116 and the external thread of the body 118 have a different pitch from the remaining threads. And, as before, locking of the bolt 124, and thus the valve closure member in the desired position is achieved by rotating the part 114 relative to the part 112 to move their matching threads out of register. The spring 122 then urges the two parts to remain in this locked position.

Another valve control locking element 130 is shown in Fig. 8 and differs from the element 110 mainly in that a part 132 fixed relative to the valve body has a tubular, externally and internally threaded boss 133 while a part 134 co-operating with the part 132 has a stepped bore 136. A threaded bolt 124 connected to a valve closure member again extends through the parts 132.

134, and its thread engages with the internal thread of the boss 133, and with a matching thread within the smaller region of the bore 136, these threads having a different pitch from the external thread of the boss 133 and a mating thread within the larger region of the bore 136.

Locking is achieved through rotating the part 134, by means of a Icver arm 138, relative to the part 132 and is maintained by a spring washer 140 as described with reference to Fig. 2.

Turning now to Fig. 9, a locking nut of the type shown in Figs. I and 2 or Figs.

3 and 4 is mounted on the end of a rod 160, connected to a clutch member, for example, or a hand brake cable, and is locked on the rod so as to retain the clutch member in a desired position or the brake cablc at a desired tension.

The described elements are particularly suitable for use in situations when safety is of paramount importance, for example, in places where vibration could cause the loosening of a bolted device with undesirable consequences, as in high speed forms of transport. Another important application is in the field of surgical devices which are used within the body and which, when tightened must not come loose. However they are equally applicable to other less demanding situations where a reliable locking element is required.

Claims (9)

WHAT I CLAIM IS :-

1. A locking element which comprises two co-operating parts having mating threads enabling the parts to be relative rotatable and having respective matching threads with a pitch which differs from that of the mating threads, the parts by virtue of the difference in pitches being relative rotatable from a position wherein the respective matching threads form an extension one of the other and are capable of receiving a complementarily threaded member, into a locking position wherein the respective matching threads do not form an extension one of the other for locking the respective matching threads against respective thread portions of the complementarily threaded member.

2. An element as claimed in claim I wherein one part has a stepped bore whose larger portion is provided with the respective mating threads and whose smaller portion is provided with the respective matching thread, the other part having a tubular portion formed externally with the respective mating thread and internally with the respective matching thread.

3. An element as claimed in claim I wherein one part has a tubular portion formed externally with the respective matching thread and internally with the respective mating thread, the other part having a cylindrical portion with the respective matching thread formed thereon and an extension or reduced diameter on which is formed the respective mating thread.

4. An element as claimed in any preceding claim, further comprising resilient means arranged yieldingly to urge the two cooperating parts towards the locking position.

5. An element as claimed in claim 4, wherein the resilient means comprises a spring washer disposed between respective shoulders on the two parts so as to form a helical turn when the parts are in the locking position, the ends of which turn are arranged to bite into the shoulders in a movement of the parts towards the initial position.

6. An element as claimed in any of claims I to 3, further comprising a stop arranged to act on the parts in the locking position to hinder return of the parts to the initial position.

7. An element as claimed in claim 6 wherein the stop comprises a C-clip supported in tension on respective shoulders on the two parts and arranged to snap into a relaxed condition between the shoulders as the parts are moved into the locking position.

8. A locking element constructed substantially as herein particularly described with reference to and as illustrated in Figs.

1 and 2; Figs. 3 and 4; Fig. 5 ; or Fig. 6 of the drawings accompanying the Provisional Specification.

9. A locking element constructed sub stantially as herein particularly described with reference to and as illustrated in Fig.

7; Fig. 8; or Fig. 9 of the accompanying drawings.