A LEVER SPINDLE

This invention concerns lever spindles for door latches of the kind where a latch bolt follower within the latch has a central aperture to receive a mid-region of a spindle which passes through a door and through the latch bolt follower, the ends of which spindle are received within respective apertures within a pair of door handle levers.

Conventional lever spindles are of solid construction usually of mild steel and are some 8mm square in section and approximately 100mm to 110mm in length. As there are very many manufacturers of door latches, door handles and lever spindles, there is a tendency for such spindles to be made with a certain tolerance such that it may be easily introduced into the latch bolt follower and into the respective handle levers. This tolerance can result in an excessive clearance between the parts, requiring strong return springs in the latch and in the door handles to ensure positive operation.

It is an object of the present invention to provide a lever spindle which is to some extent oversize but which is flexibly compressible to fit tightly within a latch bolt follower thus avoiding the problems experienced by excessive clearances.

According to the present invention there is provided a lever spindle for a door latch of a kind where a latch bolt follower has a central aperture to receive a mid-region of a spindle the ends of which are received within respective apertures in a pair of door handle levers; characterised in that the spindle comprises a pair of cambered elongate plates arranged in mutually superimposed relationship thus to define a space therebetween in a mid-region of the plates but fixed in face to face abutment in end regions thereof, thus to be compressible in said mid-region.

The plates may be fixed in said end regions by rivets.

The plates may be fixed in said end regions by welding.

The plates may be of carbon steel.

The plates may be of spring steel.

The space between the plates at a mid-point thereof may be at or in the region of 1mm.

The ends of the plates may be chamfered to facilitate introduction into a latch bolt follower.

Each plate may be chamfered along its length such that when the plates are superimposed a v-shaped groove is provided along opposed sides of the spindle.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:-

Fig. 1 is a side view of a lever spindle made in accordance with the invention;

Fig. 2 is a section taken on line a-a of Fig. 1 ; and Fig. 3 is an end view of the spindle.

Referring now to the drawings the lever spindle indicated generally at 10 comprises a pair of cambered elongate plates 11 , 12 of carbon steel or spring steel arranged in mutually superimposed relationship with its end regions 13 in face to face abutment and fixed together by rivets 14. The cambered form of the plates 11 , 12 thus results in a tapered space 15 being retained within the plates such that in the finished spindle the central or mid-region thereof is resiliently compressible to close the space.

In the example illustrated the plates may be typically some 100mm to110mm in length and 8mm wide. The spindle is of square section at its ends and of some 8mm across. The rivets 14 pass through the two plates each at some 5mm from the ends thereof.

The ends of the plates 11 , 12 are chamfered as shown at 16 to facilitate introduction into a latch bolt follower. Each plate 11, 12 is chamfered along its length such that when the plates are superimposed a v-shaped groove 17 is provided along two opposed sides of the spindle.

At the mid-point of the spindle the space 15 is approximately 1 mm in depth so that the overall height of the spindle at that point is in the region of 9mm.

In use, when the spindle is introduced into a latch bolt follower of a door latch, the plates are constrained by the size of the aperture in the follower and are thus compressed to take up any clearance therein which in turn results in a tight fit of the spindle within the follower.

The end regions of the spindle protrude from the door to be received within respective apertures in a pair of door handle levers. By providing a tight fit within the latch bolt follower, most of the tolerances usually found in such assemblies are taken up leaving only a small clearance between each end of the spindle and its respective handle lever.

Some handle levers have grub screws to assist in providing a tight fit with the spindle and in this case the v-shaped groove 17 provides a seating for such a screw so that, again, a tight fit between the spindle and the door handle lever may be achieved.

In the event that the spindle is of excessive length, particularly when applied to a door which is of less thickness than normal, it is possible for one or both ends of the spindle to be cut once it is introduced into the latch bolt follower. Preferably, one end would remain connected by the rivet 14 and the other end would be cut to length. Thus, the spindle would remain intact if removed subsequently.

It is not intended to limit the invention to the above example only. For example, the rivets 14 may be replaced by spot welding of the plates or by screws.