A METHOD AND MEANS OF ASSEMBLING LOCK CYLINDERS BACKGROUND TO THE INVENTION

This invention relates to a method of assembling lock cylinders and a means for carrying out the method. The invention is more particularly directed to the assembly of so-called European ("Euro") pin lock cylinders or any other front loaded pin type tumbler lock.

A Euro lock can be described as a cylinder with two plugs sharing the same axis of rotation that operates a cam(s) situated between them. A Euro half lock cylinder is a cylinder of similar construction to the double cylinder with only one plug.

Typically Euro lock cylinders, as manufactured by a lock manufacturer, are sold to a customer in the form as manufactured. However, there is an increasing requirement for lock cylinder suppliers or locksmiths to re-key a cylinder in order to comply with a customer's requested key number. This re-keying process involves dismantling the lock cylinder, i.e. removing the plug from the housing changing the pins in the plug and then reassembling the cylinder. This is a time consuming exercise and one that places increasing time demands on lock suppliers/locksmiths due to the increasing number of requests for specific key numbers.

The term plug is used in the art interchangeably with terms such as barrel and core. For ease of description the term plug will be used herein.

With other types of key cylinders it is known for manufacturers to supply sub-assembled cylinders where the housing pins are pre-loaded and held in place with a removable keeper plug. This enables a lock supplier/locksmith to re-key the lock plug and then insert this into one end of the lock cylinder housing and in doing so push the removable keeper plug out the other end of the lock cylinder. However, this is not possible with a Euro cylinder

because the removable keeper can only be removed from the cylinder housing via the same opening into which the lock plug is inserted. Consequently, use of a known removable keeper plug is not an option with the Euro cylinder.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method of installing a lock plug in a sub- assembled Euro lock cylinder.

A further object of the invention is to provide a means of installing a lock plug in a sub- assembled Euro lock cylinder.

Broadly in one aspect the present invention consists of a method of installing a lock plug in a sub-assembled Euro lock cylinder housing, said sub-assembled lock cylinder housing having a removable pin keeper plug to retain the pins in the lock cylinder housing, the method including the steps of inserting into the sub-assembled lock cylinder housing a retaining clip a pin retaining part of which slidingly engages with the keeper plug to assume a pin retaining position, withdrawing the keeper plug from the lock cylinder housing while retaining the retaining clip in place, inserting a lock plug through the same end of the lock cylinder housing from which the keeper plug has been removed, and removing upon completion of insertion of the plug, the retaining clip.

According to a second broad aspect of the invention there is provided a removable pin keeper plug for installation in a sub-assembled Euro pin lock cylinder housing, the keeper plug being of a cylindrical shape and dimensioned to be engageable in the bore of the lock cylinder housing to retain pins in the cylinder housing, the keeper plug including a longitudinal groove into which, in use, a pin retaining part of a retaining clip can engage to retain the pins in the lock cylinder housing upon the keeper plug being removed from the bore of the lock cylinder housing.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following more detailed description of the present invention reference will be made to the accompanying drawings in which:-

Figure 1 is a perspective illustration of a Euro five pin sub-assembled lock cylinder housing and a retaining clip,

Figure 2 is a perspective view of the removable pin keeper plug,

Figure 3 is a side elevation view of the pin keeper plug,

Figure 4 is an end elevation view of the pin keeper plug looking toward the flanged end thereof, and

Figure 5 is an end elevation view from the opposite direction.

DETAILED DESCRIPTION OF A PREFERRED EMBOIDMENT OF THE INVENTION

In the following more detailed description of the invention according to the present invention, the removable pin keeper plug 10 will be illustrated and described in a form suitable for five and six pin Euro pin lock cylinders. This is by way of example.

Referring to Figure 1 there is shown a Euro five pin cylinder E which, in accordance with conventional construction, has midway in the length thereof a cam M. Also in accordance with conventional Euro cylinder construction the Euro cylinder E incorporates a housing formed by a cylindrical body B in which extends a bore and into which a lock plug (not shown) is inserted. Pins (not shown) reside in pin chambers in the body section S.

According to the present invention the Euro cylinder E is supplied by the manufacturer in a sub-assembled state this being achieved by the insertion into the body B of the removable pin keeper plug 1 0. This keeper plug 10 remains in place in the sub-assembled lock until such time as it is removed for the insertion of the lock plug. The keeper plug 10 can, therefore, be considered to be in the nature of a sacrificial plug as it is disposed of once removed from the Euro cylinder E.

Referring to Figures 2-5, the keeper plug 10 is formed by a cylindrical body 1 1 which is hollow. Preferably it has therein a bore 1 2. This bore 12 can either extend completely through the body 1 1 or be a blind bore i.e. closed at one end.

At one end of the body 1 1 is a flange 1 3. This flange 1 3 abuts, as shown in Figure 1 , the end of the body B of the Euro cylinder housing when the keeper plug 10 is fully installed therein. It will be appreciated by those skilled in the art that for a double Euro block cylinder a keeper plug 10 will be inserted in each end of the body B.

The length of the body 1 1 of the keeper plug 10 will be such as to span the length of the bore in the body B so as to engage with and retain in place the pins. Therefore, in respect of a five or six pin Euro cylinder the length of the body 1 1 measured from the inside face of the flange 1 3 to the distal end of the body 1 1 will be in the order of 34mm.

Formed through flange 1 3 and preferably the full length of the body 1 1 of the keeper plug is a longitudinally groove 14. As can be seen from Figures 2-5 the groove 14 is of angular cross-section. This is the preferred form of the groove 14.

In Figure 1 there is shown a retaining clip 1 5. The clip 1 5 includes a tab 1 6 from which projects at right angles three prongs being a central prong 1 7 and a pair of outside prongs 18. The central prong 1 7 is of a cross-sectional shape and dimensions such that it can

slidingly engage in the groove 14. In a preferred form the prongs 1 7 and 1 8 are of an angular cross-sectional shape as illustrated in Figure 1 .

As is also evidence from Figure 1 the tab 16 is transverse to the length of the prongs and the central retaining prong 1 7 lies in a plane which is spaced from a plane in which both prongs 1 8 are located. The side prongs 1 8 are spaced from and parallel to the retaining prong 1 7.

A lock supplier/locksmith having received a request for a particular key will re-key the lock plug. Once this operation has been completed the re-keyed plug will be inserted in a sub- assembled Euro cylinder housing. This is achieved by installing the retaining clip 16 in the Euro cylinder housing by inserting the central prong 1 7 into the groove 14. This will result in the outside prongs 1 8 locating against the outer surface of the Euro cylinder housing at about the interface of the body B and the projecting body section S. The disposition of the prongs 1 7 and 1 8 and the location of the prongs 1 8 in the aforesaid position ensures that the clip 16 remains firmly in place.

During the insertion of the prong 1 7, it will engage with and press the pins which prior to the insertion of the prong will have engaged against the floor 14' of the groove 14. The length of the prong 1 7 is, therefore, sufficient to span over all of the pins in the sub- assembled cylinder and, therefore, retain the pins.

With the retaining clip 1 5 in place the pin keeper 10 can be removed. This thus leaves the retaining clip 1 5 in place thereby retaining the pins in the lock housing. The lock plug is then inserted into the body B and when fully installed the retaining clip 1 5 is removed.

Accordingly, as a result of the inter-relationship, it is possible between the removable keeper 10 and the retaining clip 1 5 that a lock plug can be inserted into the lock cylinder housing through the same opening from which the removable keeper plug has been removed. As a result, it is possible to have a sub-assembled Euro pin cylinder thereby

enabling a lock supplier/locksmith to receive as separate unit the sub-assembled assembly and the lock plug, which removes the current need to firstly disassemble the Euro cylinder before re-keying the barrel.

It is then a simple procedure to insert the retaining clip 1 5, remove the keeper plug 10, install the correctly keyed lock plug and remove the retaining clip 1 5. This is a far less time consuming operation than the conventional method currently practised with Euro cylinders thereby resulting in a more efficient pre-pinning operation of the lock plug to be carried out.