GB2154542A - Screw adjuster - Google Patents

Abstract

A screw adjuster comprises a tube (3) with an internal screw-thread with which an externally screw-threaded rod (7) is engaged and an operating handle or lever (10) comprising a pair of slotted arms (11, 12) pivotally mounted on the tube (3) by means of pins (14) which are located in the slots of said arms (11, 12). The ends of the arms (11, 12) are connected together by arcuate bridge elements (15) which extend in opposite directions and which are engageable with the tube (3) when the arms are located in a stowage position in which they extend substantially parallel to the longitudinal axis of the tube as shown in the drawing. The arms can be pivoted from this position to an operative position in which they can cause rotation of the tube (3). The tube (3) is mounted for rotation in bearings (4) in lugs (5, 6) on base (2). <IMAGE>

Description

SPECIFICATION Screw adjuster This invention relates to a screw adjuster.

Screw adjusters take many forms and are used for many different purposes. These may range from tighening devices for guy ropes to screw jacks for automobiles. All of these adjusters, however, work on the same principle i.e. a screwthreaded bar is connected to a first member to be acted on and a nut arrangement, running on the bar is connected to the second member to be acted upon.

Thus, in all cases, it is necessary to rotate either the bar or the nut relative to the nut or bar respectively. This, however, causes problems in many cases where access to the adjuster is limited. In these circumstances, it is often necessary to use special tools or to provide complicated ratchet or gearing arrangements.

The present invention seeks to provide a screw adjuster in which some or all of the above-mentioned disadvantages of existing adjusters are obviated or substantially reduced.

According to the invention, there is provided a screw adjuster comprising a screw-threaded male member, a screw-threaded female member, said members being relatively rotatable and one of said members being capable of axial movement relative to the outer member, wherein means are provided for causing relative rotation between said members, said means being permanently mounted on one of said members and being movable between a first position in which it is capable of rotating the associated member with respect to the other member and a second position in which said means extend substantially parallel to the axis of the screwthreads on said members.

Preferably the means for causing relative rotation comprises a lever arranged to rotate the female member and pivoted thereto. The pivot may comprise a pin on the female member co-operating with a slot in the lever.

Suitably, one form of adjuster may comprise a base member having spaced upstanding lugs in which a tube is rotatable. The tube is internally screw threaded, at least in part, and co-operates with a threaded rod located inside the tube. The lever may comprise a pair of slotted side arms connected together at each end by bridge elements shaped to pass around the tube.

The invention will now be described in greater detail, by way of example, with reference to the drawings, in which: Figure 1 is a front view of one embodiment of a screw adjuster according to the invention; Figure 2 is a side view of the adjuster of Figure 1 showing its operating lever in its stowage position; and Figure 3 is a side view similar to Figure 2 but showing its operating lever in its operative position.

Referring to the drawings, a screw adjuster comprises a mounting base 2 which is provided with a series of bores 1 to enable the base to be secured to be permanently mounted at a fixed location if desired. The base 2 carries a tube 3 which is rotatably mounted between bearings 4 which are provided in upper and lower brackets 5 and 6 mounted on the base 2. The tube has an internal screw thread, at least at its upper end (as seen in the drawings). Situated within this tube 3 is an externally screw-threaded rod 7 which co-operates with the screw thread in the tube such that if the rod 7 is prevented from rotating and the tube 3 is rotated, the rod 7 will move in and out of the tube 3 depending on the direction of rotation.

The upper end of the rod 7 is threaded right to the end 8 and a connection member, such as a shackle, (not shown) may be connected to this end of the rod 7.

In order to rotate the tube 3 relative to the base 2 and thereby enable it to move the rod 7 axially, a handle or lever 10 is provided. As can be seen from Figures 2 and 3, this handle or lever 10 comprises a pair of slotted side arms 11 and 12 which co-operate with headed pins 14 mounted on opposite sides of the tube 3. The two side arms 11 and 12, which are constructed from circular rod stock, are connected together at each end by bridge elements 15 adapted to fit around the tube 3 when in the position shown in Figure 2. It will be seen that the bridge elements 15 extend in opposite directions so that they are located on opposite sides of the tube 3 as shown in Figure 2.

The operation of the adjuster will now be described.

With a connector provided on the end 8 of the rod 7, the connector is connected to an element to be moved. This might, for example, be a guy rope which it is desired to tighten. It will be appreciated that with the connector connected, the rod 7 will be unable to rotate relative to the base 2.

The lever 10 is then pulled out from the tube 3 from its position shown in Figure 2, (i.e. its stowage position) to its position shown in Figure 3 (i.e.

its operative position). In this latter position, it can be used like a tommy bar to rotate the tube 3, the lever arrangement being slid along the pins 14 analogously to the sliding of a tommy bar on its apertures.

However, once the desired adjustment has been carried out, the lever arrangement 10 can be folded against the tube again as shown in Figure 2. It will be appreciated that the lever 10 will only fold in one end position of said lever since in the other end position the bridge element 15 will prevent pivoting of the lever to the folded position.

The radius of curvature of the bridge elements 15 is desirably slightly less than that of the tube 3 so that the bridge elements, and hence the whole handle or lever 10, can be held in the stowage position shown in Figure 2 by an interference fit. Alternatively, a ring or other device may be provided on the tube 3 which is designed to be slid over the handle or lever 10 to maintain the same in the stowage position.

The brackets 5 and 6 may be permanently secured to the base 2, e.g. by welding, as in the case of the bracket 6 shown in the drawings. However it is also possible for the brackets to be detachably mounted on the base 2 by means of screws 16 engaging in screw-threaded bores in the base 2 as in the case of the bracket 5 shown in the drawings. If both brackets are detachable, the screw adjuster can be removed from the base 2 for use in other applications provided that means are provided for restraining one of the tube 3 or the rod 7 from rotating when the other is rotated.

It will be appreciated that various modifications may be made to the above described embodiment without departing from the scope of the invention.

For example, means could be provided on the screw adjuster itself for preventing rotation of the rod 7. This could be achieved by axially extending grooves or flutes co-operating with the aperture in the bracket 5 through which the screw-threaded rod 7 passes. Any suitable connection could be provided at the end of the rod. For example, the connection could be in the form of a jack connector which co-operates with a corresponding connector on a vehicle so as to provide a vehicle jack.

The base could be varied to provide for a stand at the bottom instead of at the side as shown. The roles of the tube 3 and rod 7 could be reversed, the tube moving axially and the rod being rotated by the lever arrangement. Where it is desired to use the invention as a cable tightener, for example, the base could be removed or omitted entirely and the tube could be provided with its own connector.

It is also possible to incorporate the adjuster in a rod, for example of a linkage assembly, the ends of the adjuster being connected to joints or the like.

Different formations of the lever 10 could be provided, the lever being formed, for example, from stamped and bent sheet metal.

In a modification of the screw adjuster according to the invention, the male member is provided with a first, right-handed screw-thread and a second, left-handed, screw-thread which may be spaced from the first screw-thread. A respective female screw-threaded member is engaged with each of the screw-threads on the male member.

This arrangement permits adjustment to take place simultaneously at both ends of the adjuster. The pitch of the screw- threads may be the same or one screw-thread may have a finer pitch than the other. The diameters of the screw-threaded portions of the male member, and hence also the diameters of the two co-operating female members, may likewise be the same or different from one another.

Means may be provided for locking the male and female members in any desired adjusted position.

The locking means may also serve to hold the handle or lever in its stowage position or, alternatively, the locking means may be provided on the handle or lever so as to immobilise the screw-threaded members when the handle is moved into its stowage position.

As can be seen, the screw adjuster according to the invention is easy to operate, even in relatively tight spaces, the means for applying the screw movement acting readily in a reduced space but being at the same time attached to the member which it is turning so that it cannot be lost. Equally the screw movement applying means is foldable substantially parallel to the screw axis so as to take up a minimum amount of space when not in use.

Claims (25)

1. A screw adjuster comprising a screwthreaded male member and a screw-threaded female member, said members being relatively rotatable and one of said members being capable of axial movement relative to the other member, wherein means are provided for causing relative rotation between said members, said means being permanently mounted on one of said members and being movable between a first position in which it is capable of rotating the associated member with respect to the other member and a second position in which said means extend substantially parallel to the axis of the screwthreads on said members.

2. A screw adjuster according to claim 1, wherein the means for causing relative rotation between said members comprises a lever arranged to rotate the female member and pivotally mounted thereon.

3. A screw adjuster according to claim 2, wherein the female member is provided with a pin on which the lever is pivotally mounted.

4. A screw adjuster according to claim 3, wherein the lever is provided with a slot adpated to receive said pin on the female member.

5. A screw adjuster according to claim 1, wherein said adjuster further comprises a base member having a pair of upstanding lugs between which a tube is rotatably mounted, said tube being provided with an internal screw-thread, at least in part, and constituting said female member, the screw-thread of said tube co-operating with a screw-threaded rod extending through at least one of the lugs and constituting said male member.

6. A screw adjuster according to claim 5, wherein the lugs are detachably mounted on the base member.

7. A screw adjuster according to claim 5 or claim 6, wherein the screw-threaded rod is provided with means for preventing it from rotating relative to the tube and the base member.

8. A screw adjuster according to claim 7, wherein the rotation preventing means comprise a connection member mounted on an end of the rod which projects from the tube through said one of the lugs.

9. A screw adjuster according to any one of claims 5 to 8, wherein the means for causing relative rotation between the members comprises a lever arranged to rotate the tube and pivotally mounted thereon.

10. A screw adjuster according to claim 9, wherein the tube is provided with a pair of diametrically opposite pins on which the lever is pivotally mounted.

11. A screw adjuster according to claim 10, wherein the lever comprises a pair of slotted side arms which are connected together, the slot in each side arm being adapted to receive a respective one of the pins on said tube.

12. A screw adjuster according to claim 11, wherein the side arms of the lever are connected together at each end by bridge elements adapted to fit at least partially around the tube when the lever is in said second position.

13. A screw adjuster according to claim 12, wherein the bridge elements extend from the plane of the major portions of the side arms of the lever in opposite directions whereby they are located on opposite sides of the tube when the lever is in said second position.

14. A screw adjuster according to claim 12 or claim 13, wherein the tube has a circular cross-section and wherein the bridge elements are arcuate.

15. A screw adjuster according to claim 14, wherein the radius of curvature of the bridge elements is slightly less than that of the tube so that the bridge elements are effective to hold the lever in said second position by an interference fit with the tube.

16. A screw adjuster according to any one of claims 11 to 14, wherein means are provided for holding said side arms of the lever in said second position.

17. A screw adjuster according to claim 16, wherein said holding means comprise a ring or like device provided on the tube and adapted to be slid over the arms of the lever to hold the latter in said second position.

18. A screw adjuster according to any one of claims 11 to 17, wherein the slots in said side arms of the lever extend throughout substantially the entire length of the side arms whereby the lever is engageable with the pins at either end.

19. A screw adjuster according to any one of claims 5 to 18, wherein the screw-threaded rod extends though both lugs of the base member, the rod having a right-handed screw-thread at one end and a left-handed screw-thread at its other end and the tube being provided with co-operating screwthreads at or adjacent to each of its ends.

20. A screw adjuster according to any one of claims 5 to 18, wherein a second screw-threaded rod is provided which co-operates with a second screw-thread provided in the tube and which extends through the other one of said lugs on the base member, the threads of said second screwthreads extending in an opposite direction of rotation to that of the threads of the first-mentioned screw-threads.

21. A screw adjuster according to claim 19 or claim 20, wherein the two screw-threaded connections have different pitches.

22. A screw adjuster according to any one of claims 19 to 21, wherein the two screw-threaded connections have different diameters.

23. A screw adjuster according to any one of claims 5 to 22, wherein the base member is provided with a number of holes to permit said base member to be secured to a structure by screws, bolts or the like.

24. A screw adjuster according to any preceding claim, wherein means are provided for locking the male and female members in any desired adjusted position.

25. A screw adjuster substantially as described herein with reference to the drawings.