This invention relates to key operated locks of the type wherein there is a central rotatable barrel into which a bitted key is inserted in order to position locking pins, which normally hold the barrel non-rotatable in a housing, so the barrel can be rotated relative to the housing by applying a rotational torque to the key inserted in the barrel.

In locks of the above type "picking" techniques used for an unauthorised operation of the locks involves the simultaneous use of two instruments. The first instrument is of fine form and is inserted into the key slot in the barrel to manipulate the pins into positions which will enable the barrel to be turned. The second instrument is inserted into the entry end of the key slot in the barrel, but so as not to interfere with the manipulative operation of the first instrument, and a rotational torque is applied through the second instrument to the barrel. When the pins are located in a "barrel freeing" .position by the first instrument the torque applied by the second instrument will cause the barrel to rotate and a latch means coupled to the inner end of the barrel is caused to be moved to a release position.

The success of the above picking technique depends- nn me.

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application of torque to the barrel at its outer (exposed) end and the transmission of that torque through the barrel to the latch means. This invention makes the above technique ineffective by providing a multi-section barrel with each section held no -rotatable. Each section is able to rotate relative to its adjacent section or sections when its locking pins are released and means is provided to prevent axial movement of the barrel when so released. The result is that even if all barrel locking pins are released torque applied to the outer end of the outermost section will not result in the application of turning torque to the other barrel section or sections.

Broadly, the invention can be said to comprise a key operable barrel lock comprising a housing with a cylindrical opening therein, a barrel rotatably housed in said cylindrical opening but restrained against axial removal from said cylindrical opening, said barrel comprising a plurality of individually rotatable barrel parts each restrained against rotation by axially movable pin means entered into holes in said housing and into holes in said barrel parts, a key receiving key slot extending londitudinally through the barrel parts when said pins means are located in the holes in said barrel parts, said key slot being in communication with the holes in the respective

barrel parts to enable bitting on a key body inserted into said key slot to move the pin means out of engagement with said barrel parts.

Several preferred forms of the invention will now be described with reference to the accompanying drawings in which:-

Fig.l is a perspective view of a barrel separated from its housing showing a first means to hold the barrel parts so that they can rotate one relative ^' to the other but -cannot move apart longitudinally,

Fig.2 is a fragmentary sectioned view of a connection between two barrel parts whic^permits relative rotational movement therebetween whilst preventing longitudinal separation of the parts, the interconnecting spring clip means is not shown,

Fig.3 is a view similar to Fig.2, but at 90 degress to the direction of the view of Fig.2, with the interconnecting spring clip means in place,

Fig.4 is a sectional end view on the section line 4-4 of Fig.2 with the interconnecting spring clip means in place, and

Fig.5 is a view similar to Fig.3 showing a cover mounted on an end of a barrel Dart.

As illustrated there is a housing 1 in which there is a hole

2 to rotatably support a barrel 3. The housing includes a

' ridge la in which there is housed short cylindrical pins which lie radial to the axis of the hole 2. The pins are captive and are biassed resiliently towards the hole 2 and are of different lengths. The housing pins are prevented from escaping into the housing hole 2 by engagement of their outer ends with the outer sub-surface ends of like pins housed in holes in the barrel 3, or with the bottoms of holes in the barrel 3, when the barrel is in the locked non-rotatable condition. When the barrel is released for rotation the outer ends of the housing pins will bear on the periphery of the barrel. I&e lengths of the barrel pins are different and the lengths of the housing and barrel pins are such that when the housing and barrel pins are aligned the pins of the housing will project to varying degrees into the holes in the barrel occupied by the barrel pins, thereby preventing the rotation of the barrel.

The barrel pins are prevented from dropping into the key slot 4 in the barrel by ends to the holes housing the barrel pins. The ends are however partly removed to allow "bitting" profiles on the operative edge(s) of a key body inserted in the key slot 4 in the barrel to bear on the

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barrel pins. The bitting profile is such as to cause the abutting ends of the housing and barrels pins to lie at the periphery of the barrel 3. As a result none of the housing pins are entered into the barrel pin holes to prevent rotation of the barrel and torque applied to the key in the slot 4 results in the barrel being rotated.

As illustrated the barrel is in two parts 3a and 3b. The part 3a may have a shoulder 5 to abut the outer end of the housing 1 and there is a peripheral groove 6 in the barrel part 3a into which a free end of a grub screw 7 in the ridge la is inserted. In this way- the barrel part can be rotated but is restrained from axial disengagement from the hole 2. It will be seen that the shoulder 5 is not an essential for the retention of the barrel part 3a in the housing 1. The barrel part 3b is likewise rotatably mounted in the housing hole 2.

It will be readily understood that where a picking operation is undertaken as hereinbefore described the application of torque to the slot 4 in the barrel part 3a will not, even when all the barrel locking pins are juggled to the appropriate heights, result in rotation of the barrel part 3b. As the latch means controlled by the key/barrel arrangement just described is coupled to the barrel part 3b

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the picking operation will not result in the release of the latch means.

In the second form of the invention shown in Figs. 2, 3 and 4 the two barrel sections 3a and 3b are not restrained against longitudinal movement by screws 7 and 8 but are interconnected so as to allow the parts to be relatively rotatable but not moved one relative to the other longitudinally. More specifically, as shown in Figs. 2, 3 and 4, the barrel part 3a is counterbored at 9 to receive a spigot end 10 of the barrel part 3b. There is an annular groove 11 around the spigot end ,10 aligned with a pair of grooves 12 and 13 in the barrel part 3a with the grooves 12 and 13 intersecting the bore 9 of the barrel part 3a.

A "hairpin" type spring clip 14 is used to secure the parts 3a and 3b together. The clip legs 15 and 16 have portions which, when the clip 14 is mounted on the part 3a, extend into the groove 11 of the spigot 10 at diametrically opposed locations. The parts 3a and 3b are thus secured together ^* in the required manner against relative longitudinal movement.

The foregoing has been limited to two barrel parts 3a and 3b but naturally more than two parts can be used where

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considerations of size and complexity of construction permit.

As a special precaution against determined lock breakers, those who are prepared to attack locks with more sophisticated tools than simple lock "picking" tools, a front cover is provided for the lock. It will be noted that by drilling a hole or holes into the barrel part 3a and on into the part 3b a pin can be inserted to tie the two parts together thereby overcoming the advantage of the rotatable connection between those parts. To prevent this a front cover member indicatd 17 in Fig. 5 is mounted in front of the barrel part 3a. The cover 17 has a spigot 18 which fits into a counterbore 19 in the end of the part 3a opposite to that into which the spigot 10 of barrel part 3b enters. The parts 17 and 3a are. held together with a spring clip such as that identified 14 in Fig. 4.

The cover 17 is made of hardened steel or like material to prevent or at least discourage an attack directed to drilling holes into the several parts to negate the ability of adjacent barrel parts to rotate relatively, in the manner described above. The cover 17 can rotate freely and does not include any pins for key operation. This has the added advantage that a direct attack to "drill out" the whole

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barrel, which is a common form of lock breaking technique by determined burglars, will be ineffective as the cover will simply rotate as the drill rotates thereby preventing access to the parts 3a and 3b of the lock proper.

It will be understood that the arrangement shown in Figs. 2 to 4 can be oppositely configured with the spigot on the barrel part 3a and the socket on the barrel part 3b.

The invention can be broadly said to reside in the splitting of the barrel of a key operated lock, into interconnected parts capable of relative rotational movement.

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