Title of Invention

"IMPROVEMENTS IN ROLLER BOLT LATCHES"

Abstract

A roller bolt latch has a casing (1) and a roller bolt (3) arranged to project from the casing (1). Adjustment means are provided to adjust the extension of the roller bolt (3) from the casing (1), the adjustment means comprising a lever (13) which is arranged to act on a spindle (5) connected to a stirrup (2) in which the roller bolt (3) is rotatably mounted and an adjustment screw (16) which is accessible from outside the casing (1). The arrangement is such that turning the screw (16) in one direction is effective to cause the lever (13) to act on the spindle (5) to increase the projection of the roller bolt (3) from the casing (1) and turning the screw (16) in the opposite direction is effective to cause the lever (13) to act on the spindle (5) to decrease the projection of the roller bolt (3) from the casing.

Full Text

IMPROVEMENTS IN ROLLER BOLT LATCHES This invention relates to improvements in roller bolt latches. A problem encountered with existing roller bolt latches is that when the, roller bolt is pushed back when a door to which the latch is fitted is being closed, the spindle on which the roller bolt is mounted projects out of the back of the latch casing. If this is not realised when the roller bolt is being fitted to a door, the spindle will abut the bottom of the socket in the door which has been made for the latch casing and the roller bolt cannot be fully depressed. Another problem with the existing roller bolt latches was in the adjustment of the projection of the roller latch from the foreend which could only be done with the latch casing removed from the door because the adjustment was from the back of the casing. Adjustment was therefore not only laborious and time-consuming but it was also imprecise involving a certain degree of guesswork concerning the adjustment required. It has been proposed to solve these problems by providing a plate in the latch casing which extended across the casing and which was arranged to act on the spindle of the roller bolt. A pair of adjustment screws were arranged to act on the plate in order to adjust the position of the plate in the casing and, hence, the projection of the roller latch from the foreend. While this permitted adjustment from the front of the casing, this arrangement was not satisfactory because if the screws were not adjusted evenly, the plate could jam in the casing. The present invention aims to provide a better solution to the above-mentioned problems encountered with existing latches. According to the invention, there is provided a roller bolt latch having a casing and a roller bolt arranged to project from the casing, wherein means are provided to adjust the extension of the roller bolt from the casing, said adjustment means comprising a member arranged to act on a spindle which is arranged to act on the roller bolt, and an adjustment screw which is accessible from outside the casing and which is arranged to act on said member, the arrangement being such that turning the screw in one direction is effective to increase the projection of the roller bolt from the casing and turning the screw in the opposite direction is effective to decrease the projection of the roller bolt from the casing. Preferably, the adjustment screw is arranged so that it can be turned with a foreend of the latch in position on the casing. The head of the adjustment screw is desirably located in a recess in the foreend. The member which is arranged to act on the spindle preferably takes the form of a lever which is pivotally mounted at one end in the casing and which is engageable at its other end by the adjustment screw, the lever being arranged to act on the spindle between the ends of said lever. The said one end of the lever is desirably mounted on a pin projecting from a wall of the casing. The other end of the lever is preferably bent round a collar having a screw-threaded bore which is engaged with the adjustment screw. An intermediate part of the lever can be provided with a bore through which the spindle extends. According to a preferred embodiment, the lever curves round a collar mounted on the spindle and is held in place on the spindle by a circlip. The collar is desirably provided with projections which extend into respective slots provided in a wall of the casing and in a cover plate which is detachably fitted to the casing. 2 The invention will now be described in detail, by way of example, with reference to the drawings, in which:- Fig. 1 is a front elevation of one embodiment of a roller bolt latch according to the invention; Fig. 2 is a section taken on the line II - II in Fig. 1 in the direction of the arrows; and Fig. 3 is a section taken on the line III - III in Fig. 1 in the direction of the arrows. In the drawings, like parts are directed by like reference numerals. Referring to the drawings, the roller bolt latch according to the invention comprises a casing 1 in which is located a U-shaped stirrup 2 in which a roller 3 is rotatably mounted on a pin 4 which is fixed in the arms of the stirrup 2 between which is located the roller 3. The stirrup 2 and roller 3 extend through a slot in a front wall 11 of the casing 1 and a spindle 5 is secured to the web of the U-shaped stirrup 2. A collar 6 is mounted on the spindle and a coil spring 8 is also mounted on the spindle between the stirrup 2 and the collar 6. A pair of pillars 9 having screw-threaded bores extend upwardly from the base of the casing 1 and a cover plate 10 for the casing can be secured to the casing by passing screws (not shown) through holes in the cover plate 10 to engage in the screw-threaded bores in the pillars 9. The base of the casing 1 and the cover plate 10 are provided with aligned slots 21 in which are located projections 7 which extend from the collar 6. The adjustment means for the roller 3 comprise a pin 12 which extends upwardly from the base of the casing 1 and on which one end of a lever 13 is pivotally mounted. The lever is provided with an aperture intermediate its ends through which the end of the spindle 5 remote from the stirrup 2 extends. This part of the lever is curved around the collar 6 and the lever is held on the spindle 5 by a circlip 14. The other end of the lever 13 ends in a loop which fits around a -^ collar 15. The collar 15 is provided with a screw-threaded bore and is engaged by a screw 16. The head 17 of the screw 16 is mounted in a bore in the front wall 11 of the casing 1 and the screw extends across the casing through a bore in a shoulder 19 projecting upwards from the base of the casing 1, through a first bore in the looped end of the lever 13, engages with the screw-threaded bore in the collar 15 and then passes through a second bore in the looped end of the lever 13. A foreend 18 which is mounted over the front wall 11 of the casing 1 is provided with a bore so that the head 17 of the screw 16 is accessible. A coil spring 20 is mounted on the screw 16 between the collar 15 and the shoulder 19. In order to adjust the distance by which the roller 3 extends from the foreend 18, it is merely necessary to engage the head 17 of the screw 16 with a screwdriver and to turn the screw in the direction of the double arrow shown in Fig. 1 of the drawings. Turning the screw in one direction towards the "+" sign is effective to move the collar 15 towards the front wall 11 of the casing 1. This in turn causes the looped end of the lever 13 to move towards the wall 11, the lever pivoting about the pin 12 and the intermediate part of the lever engaging the collar 6 forcing said collar and hence the spindle 5 towards the front wall 11 of the casing 1. This has the effect of causing the stirrup 2 and roller 3 to move outwards and to project further from the foreend 18. Turning the screw 16 in the opposite direction towards the "-" sign is effective to move the collar 15 away from the front wall 11 of the casing 1. Thus in turn causes the looped end of the lever 13 to move away from the front wall 11, the lever again pivoting abut the pin 12 and the intermediate part of the lever bears against the circlip 14 to move the spindle 5 away from the front wall 11 of the casing 1. This has the effect of causing the stirrup 2 and roller 3 to retract inwards to reduce the projection of the roller 3 from the foreend 18. It will thus be seen that, by means of the invention, the projection of the roller from the foreend can be easily and reliably adjusted without the necessity to open the casing or to remove the casing from a door in which it has been installed. 4 It should also be noted that the force exerted on the stirrup 2 by the spring 8 is unaffected by the position of the collar 6 in the casing. Movement of the said collar 6 in the casing is limited by the ends of the slots 21 in the base of the casing 1 and in the cover plate 10 in which the projections 7 are located.: The invention is not restricted to the above-described embodiment but variations and modifications may be made without departing from the scope of the invention. For example, it is possible to dispense with a coil spring on the screw 16. The lever 13 is preferably made of spring steel but, again, this is not essential/ 5 I CLAIM : 1. A roller bolt latch having a casing and a roller bolt arranged to project from the casing, wherein means are provided to adjust the extension of the roller bolt from the casing, said adjustment means comprising a member arranged to act on a spindle, which is arranged to act on the roller bolt, and an adjustment screw which is accessible from outside the casing and which is arranged to act on said member, the arrangement being such that turning the screw in one direction is effective to increase the projection of the roller bolt from the casing and turning the screw in the opposite direction is effective to decrease the projection of the roller bolt from the casing. 2. A roller bolt latch as claimed in claim 1, wherein the adjustment screw is arranged so that it can be turned when a forend of the latch is in position on the casing. 3. A roller bolt latch as claimed in claim 2, wherein the head of the adjustment screw is located in a recess in the forend. 4. A roller bolt latch as claimed in any one of the preceding claims, wherein the member which is arranged to act on the spindle takes the form of a lever which is pivotally mounted at one end in the casing and which is engageable at its other end by the adjustment screw. 5. A roller bolt latch as claimed in claim 4, wherein the lever is arranged to act on the spindle between the ends of said lever. 6 6. A roller bolt latch as claimed in claim 4 or claim 5, wherein the said one end of the lever is mounted on a pin projecting from a wall of the casing. 7. A roller bolt latch as claimed in any one of claims 4 to 6, wherein the other end of the lever is bent round a collar having a screw-threaded bore which is engaged with the adjustment screw. 8. A roller bolt latch as claimed in claim 7, wherein a spring is mounted on the adjustment screw and is engageable with the collar. 9. A roller bolt latch as claimed in any of claims 4 to 8, wherein an intermediate part of the lever is provided with a bore through which the spindle extends. 10. A roller bolt latch as claimed in claim 9, wherein the lever curves round a collar mounted on the spindle. 11. A roller bolt latch as claimed in claim 10, wherein the lever is held in place on the spindle by a circlip. 12. A roller bolt latch as claimed in claim 10 or claim 11, wherein the collar is provided with projections which extend into respective slots provided in a wall of the casing and in a cover plate which is detachably fitted to the casing. 13. A roller bolt latch as claimed in any one of claims 10 to 12, wherein a spring is mounted on the spindle and is engageable with the collar on said spindle. 7 14. A roller bolt latch as claimed in any one of claims 8 to 13, wherein the lever is made of spring steel. 15. A roller bolt latch substantially as described herein with reference to the drawings. A roller bolt latch has a casing (1) and a roller bolt (3) arranged to project from the casing (1). Adjustment means are provided to adjust the extension of the roller bolt (3) from the casing (1), the adjustment means comprising a lever (13) which is arranged to act on a spindle (5) connected to a stirrup (2) in which the roller bolt (3) is rotatably mounted and an adjustment screw (16) which is accessible from outside the casing (1). The arrangement is such that turning the screw (16) in one direction is effective to cause the lever (13) to act on the spindle (5) to increase the projection of the roller bolt (3) from the casing (1) and turning the screw (16) in the opposite direction is effective to cause the lever (13) to act on the spindle (5) to decrease the projection of the roller bolt (3) from the casing.

Documents:

00231-kol-2004 abstract.pdf

00231-kol-2004 claims.pdf

00231-kol-2004 correspondence.pdf

00231-kol-2004 description(complete).pdf

00231-kol-2004 drawings.pdf

00231-kol-2004 form-1.pdf

00231-kol-2004 form-18.pdf

00231-kol-2004 form-2.pdf

00231-kol-2004 form-3.pdf

00231-kol-2004 letters patent.pdf

00231-kol-2004 p.a.pdf

00231-kol-2004 reply f.e.r.pdf

231-kol-2004-granted-abstract.pdf

231-kol-2004-granted-claims.pdf

231-kol-2004-granted-correspondence.pdf

231-kol-2004-granted-description (complete).pdf

231-kol-2004-granted-drawings.pdf

231-kol-2004-granted-examination report.pdf

231-kol-2004-granted-form 1.pdf

231-kol-2004-granted-form 2.pdf

231-kol-2004-granted-form 3.pdf

231-kol-2004-granted-letter patent.pdf

231-kol-2004-granted-pa.pdf

231-kol-2004-granted-reply to examination report.pdf

231-kol-2004-granted-specification.pdf