GB2215811A - Spindle for door handle - Google Patents

Abstract

A door handle spindle is provided along its length with a weakened portion in the form of a peripheral groove (21). The spindle can be of one piece and can have two such grooves (21) of semi-circular cross-section and axially spaced apart, or it can be a split spindle formed of two interconnected parts which can relatively rotate through a pin and groove connection, but which cannot move relatively axially. In this case the weakened portion (21) would be either in the spindle part (18) which has a spigot (18a) engaging in the other spindle part (17) or would be in the spindle part in which a spigot of the other part is received. When used to mount door handles at a lock fitted to a door, the spindle has the or each of its weakened portions disposed outside of the lock. The weakened portion is so arranged that the spindle shears at said portion at a torque value which is less than that which could cause damage to the lock with which the spindle is used. <IMAGE>

Description

SPINDLE This invention relates to a spindle, primarily for use with a door handle assembly to effect a connection between handles disposed respectively at either side of a door and internal components of a lock or latch operating mechanism secured to the door.

Conventionally a spindle of such a door handle assembly has a square cross-section and passes through a correspondingly shaped opening in an internal operating cam of the lock, so as to be keyed to the cam, with the result that rotation of the spindle by one of the handles causes rotation of the cam to operate components of the lock, such as a latch bolt or a dead bolt. The spindle can of course, be keyed to more than one cam, for example where different bolts are actuated depending on the direction of angular movement of the handle.

If a door is 'locked', for example if upper and lower dead bolts are in their extended positions, and cannot be released by angular movement of a handle of the door unless a key-operated deadlock is first retracted, any attempt to gain unauthorised entry by forcing the handle clockwise or anticlockwise will fail. However the torque applied to the handle will be transmitted through the spindle to the operating cam and can cause damage to the cam and/or the component or components it actuates. Such damage is more acute with locks where the components thereof are of relatively lightweight material, such as aluminium.

Not only does such damage result in the expense of replacing some or all of the lock mechanism, it can also be a relatively time consuming process.

An object of the invention is to provide a spindle which can alleviate the above mentioned problem.

According to the invention there is provided a spindle having along its length a weakened portion between two integrally connected spindle parts.

The provision of the weakened portion is to allow the portion of the spindle outside of the lock, and subject to torque via its associated handle, to shear off from the portion of the spindle in the lock at a torque value below that at which the lock is damaged. Since the lock components are undamaged and thus do not need replacing, it is merely necessary to remove the broken spindle and replace it with a new one, to which the handle is then attached.

Preferably the weakened portion is formed by machining a peripheral groove in the spindle to leave a generally cylindrical portion between opposite full size spindle portions integrally connected by said cylindrical portion. The groove could, however, be produced by other suitable means. The depth of the groove is calculated so that the spindle shears apart at the groove before any damage occurs to the lock with which the spindle is intended to be used.

Conveniently the spindle is in one piece.

Alternatively it may be a split spindle formed of two interconnected, but independently rotatable parts.

The invention also relates to a lock assembly including a spindle of the above mentioned form, a portion of the spindle being received in a lock and a further portion being disposed outside of the lock at one side thereof, with said weakened portion being outside of the lock at said one side and between said portions.

Conveniently a further portion of the spindle is disposed outside of the lock at its other side and a further weakened portion is outside of the lock at said other side and between said further spindle portion and the spindle portion in the lock, so that, in use, the application of torque greater than a predetermined value to the spindle via a handle at either side of the door to which the lock is secured, will result in shearing of the spindle at said weakened portion or at said further weakened portion, without damage to the lock.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of a spindle constructed in accordance with the invention; Figure 2 is an enlarged, fragmentary view of a weakened part of the spindle of Figure 1; Figure 3 is a side view of another form of spindle of the invention; Figure 4 is a side view of a still further form of spindle of the invention; Figure 5 is a schematic, fragmentary exploded view of a lock incorporating a spindle of the type shown in Figure 3, and Figure 6 is a view similar to that of Figure 5, but illustrating a spindle of the type shown in Figure 4.

Figure 1 shows a one-piece, square-section spindle 10, having adjacent its ends, respective notches 11 in one of its surfaces. In use, the ends of the spindle are intended to be received in the spigots of respective door handles, with respective grub screws or the like being passed through the handles and screwed down tightly into the notches to retain the handles on the spindle.

At approximately one third and two thirds along the length of the spindle are formed respective grooves 12. Each groove is normal to the length of the spindle and, as shown to an enlarged scale in Figure 2, is of semi-circular cross-section. The groove leaves a generally, cylindrical part 13, which constitutes a weakened portion of the spindle.

In use, it is intended that the spindle is engaged with a lock secured to a door, with the square-section part 14 of the spindle between the grooves 12 being received in the lock and keyed to an internal operating cam, which has a corresponding square-section hole therethrough. The grooves 12 are disposed outside of the lock at respective opposite sides thereof. The cam is arranged to operate one or more bolts of the lock, upon angular movement of either of the handles secured to the respective ends of the spindle at opposite sides of the door.

The depth of each groove has been calculated and arranged so that the part 13 will break at a predetermined torque value. Thus should the handle at, for example, the outside of the door be moved fully angularly upwards or downwards and pressure then applied to try to force the lock, the part of the spindle connected to the handle will shear away from the remainder of the spindle at the groove nearest the handle, as soon as the pressure applied produces a torque value greater than that for which the groove is designed. Moreover this torque value is arranged to be significantly lower than that which could cause damage to the lock components, especially the operating cam, by applying pressure to the handle with the door 'locked'.

Typically the spindle is 8mm. square with a length of 105mm and the groove radius is 0.8mm. For a typical kind of mortice lock it has been found that lock damage occurs at 56Nm with upward force applied to the handle, and at 47Nm with downward force applied. With the groove radius as mentioned above, shearing takes place at 34Nm for both directions of handle movement, thus clearly preventing damage to the lock.

Figures 3 and 4 show two further spindles of the invention, each being of the kind described and shown in our U.K. Patent No. 2,167,528, namely a split spindle formed by two parts which are secured together against longitudinal displacement, but which are relatively rotatable.

The spindle 15 shown in Figure 3 is of generally the same form as the spindle 10 being of square cross-section with notches 16 at its ends. One part 17 has an axial bore within which is received a cylindrical portion 18a of the other part 18 of the spindle. The cylindrical portion is of smaller cross-sectional area than the remainder of part 18 and has a pair of peripheral grooves formed at axially spaced locations thereon. The part 17 has two opposed pairs of through holes leading from the exterior into its bore, and a pair of pins 19 can be fitted in one of the two pairs of holes to engage within an aligned one of the peripheral grooves on the cylinfrical portion substantially to prevent axial movement between the parts 17 and 18, whilst permitting free relative rotation between them. A circlip 20 retains the pins in place.Figures 5 and 6 show the split spindles of Figures 3 and 4, but do not show the other through holes for alternative positioning of the circlip. If provided, these would be positioned as appropriate for altering the lock operating parts of the spindle.

A shear groove 21, of the same form and size as the grooves 12, is formed in the part 18 between the junction of the two spindle parts and the inner end of the notch 16 in part 18. The position of the groove 21 is such that it will lie outside of the lock with which the spindle is intended to be used.

Such a lock is shown in Figure 5, which Figure also shows the spindle 15, but without its notches. The lock has an operating cam 22 with a square section hole 23 so that the spindle and cam can be keyed together when the spindle is inserted in the direction of the arrow.

The insertion is continued until- the circlip 19 abuts the side of the lock, in which position the groove 21 will be disposed outside of the lock at the other side thereof, which in use would be the outside of the door to which the lock is secured. Handles would be attached to the opposite ends of the spindle respectively. The circlip 19 is retained on the spindle by notches at the corners thereof axially aligned with the pin holes.

Typically with the arrangement shown, the part 17 of the split spindle would, on rotation by its associated handle, operate a springbolt 24 of the lock as well as upper and lower operating rods 25 (only one shown), by means of an appropriate part of the cam 22. A separate part of the cam 22 on the part 18 of the spindle, between the groove 21 and portion 18a, would, via spindle part 18 and associated handle, operate the rods 25 only, with an extra turn of the key for the lock retracting the springbolt.

Thus should an attempt be made to force the lock by applying excessive force in either direction to the handle on spindle part 18 at the outside of the door, the spindle would shear at the groove 21 at the torque value given above for the spindle 10, or alternatively at any predetermined value less than that at which the lock would be damaged.

To replace the spindle is relatively easy, merely requiring removal of the handle at the inside of the door and removal of part 17 and attached portion of part 18 from the lock, with the handles being thereafter secured to the ends of a new spindle inserted through the hole 23.

Figure 5 shows the arrangement for a right hand hung door, whilst Figure 6 shows an alternative arrangement with a left hand hung door.

The spindle 26 of Figure 6 is the same form as the spindle 15, being formed of two parts 27 and 28 which are arranged for relative rotation and secured against relative axial movement by pins 29 and circlip 30.

However the shear groove 31 is formed in the longer part 28 and the circlip is positioned on the part 28 between its groove 31 and its junction with the part 27.

As described with Figure 5, the spindle 26 is inserted into a lock until the circlip 30 engages one side thereof, with the two parts of the cam 22 being keyed with respective ones of the spindle parts 27 and 28.

The remainder of the parts 27, 28 project from the door at respective inner and outer sides thereof, the groove 31 lying outside the lock at the outer side of the door.

As with the Figure 5 arrangement, the spindle part with the shear groove operates the end rods 25 only, with an extra turn of the key retracting the springbolt, whilst the other spindle part operates the end rods and the springbolt 24. Similarly the application of excessive force, upwardly or downwardly, on the handle secured to spindle part 28 will cause it to shear at its weakened portion, namely the groove 31, before any damage is done to the lock.

Naturally with whatever the type of spindle, the weakened portion can be of any suitable form and is not necessarily a groove. Its torque value at shearing will determine its suitability for use in a particular lock.

Claims (14)

1. A spindle having along its length a weakened portion between two integrally connected spindle parts.

2. A spindle as claimed in claim 1, formed in one piece.

3. A spindle as claimed in claim 1, formed of two interconnected but independently rotatable parts.

4. A spindle as claimed in claim 3, wherein said parts are co-axially aligned, one of the parts having an axial bore which receives a spigot of the other of the parts, said one of the parts carrying at least one pin extending into said bore through at least one radial hole in said one part, to engage an aligned recess or groove in said other of the parts, to interconnect said spindle parts so as to permit relative rotation but substantially no relative longitudinal displacement therebetween.

5. A spindle as claimed in claim 4, wherein said weakened portion is provided in said other of the parts.

6. A spindle as claimed in claim 4, wherein said weakened portion is provided in said one of the parts between said at least one pin and the end of said one part remote from said other part.

7. A spindle as claimed in any one of claims 4 to 6, wherein the or each pin is held in place by a retainer which acts as an abutment on said one spindle part.

8. A spindle as claimed in any one of the preceding claims, wherein said weakened portion is a peripheral groove.

9. A spindle as claimed in claim 8, wherein the groove is normal to the lengthsof the spindle and of concave semi-circular cross-section.

10. A spindle as claimed in claim 8 when appended to claim 2, wherein two axially spaced grooves are provided along the length of the spindle.

11. A lock assembly including a spindle as claimed in any of the preceding claims, wherein a portion of the spindle is received in a lock and a further portion is disposed outside of the lock at one side thereof, with said weakened portion being outside of the lock at said one side and between said spindle portions, so that, in use, application of torque greater than a predetermined value to the spindle via a handle at said one side of a door to which the lock is secured, will result in shearing of the spindle at said weakened portion, without damage to the lock.

12. A lock assembly as claimed in claim 11, wherein a still further portion of the spindle is disposed outside of the lock at its other side and a further weakened portion is outside of the lock at said other side and between said further spindle portion and the spindle portion in the lock, so that, in use, the application of torque greater than a predetermined value to the spindle via a handle at either side of the door to which the lock is secured, will result in shearing of the spindle at said weakened portion or at said further weakened portion, without damage to the lock.

13. A spindle substantially as hereinbefore described, with reference to and as shown in Figure 1 or Figure 3 or Figure 4 of the accompanying drawings.

14. A lock assembly substantially as hereinbefore described, with reference to, and as shown in Figure 5 or Figure 6 of the accompanying drawings.