Patent GB-1018502-A (GB)
Title: Improvements relating to roller latches
Inventor: MCCULLOCH DONALD GEORGE
IPC: H01H3/30
Filed: 1962-10-10
Abstract: 1,018,502. Latch fastenings. A. REYROLLE & CO. Ltd. Oct. 10, 1962, No. 38459/62. Heading E2A. [Also in Division H2] A roller latch comprises a stack consisting of one or more pairs of roller members, for example spheres or cylinders, which in the latching position are releasably held in rolling contact with one another between a pair of oppositely facing abutment surfaces 15, 17 respectively associated with two members 10, 12 so that an externally applied force between the members is opposed by a reaction transmitted between one abutment surface and the other through the points or lines of rolling contact of the roller members upon one another and in which when in the latching condition the tangential planes through the points or lines of contact of the two roller members or when there are more than one pair, of the two end roller members of the stack with their associated abutment surfaces are inclined to one another at a small acute angle in which condition the roller members are engaged by restraining means 25 which holds them in their stacked positions in latching engagement between the two abutment surfaces and latch releasing means 35 operable to cause or allow one of the abutment surfaces 17 to move relatively to the other surface 15 in such a way that the said tangential planes become convergent in the said initial direction of divergence and divergent in the opposite direction, the roller members being then free to roll away from the restraining means in the said opposite direction under the action of the applied external force and thereby to release the latch. Fig. 1 shows an embodiment using two cylindrical roller members 13, 14 and the tangential planes are indicated at 30a and 30b. The abutment surface 17 is the upper surface of a block 18 having a knife edge 19 which rests pivotally in a trough 20 formed in a bearing 21 which is secured to the member 12. The restraining means 25 is a frame which is biased to the right as shown by means of springs 27 and which holds the two roller members against a surface 31 between the abutment surfaces 15 and 17. The releasing means is a pivoted lever 35 which is mounted on a sleeve 11 attached to the member 12 and which has a detent block which in the latching position of the roller members engages a yoke plate 33 carried by a pair of arms 32 which support the abutment block 18. This engagement of the detent block 34 with the yoke plate 33 thus prevents pivoting of the abutment block and the roller members are held in their latching position. To release the latch an electromagnetic trip coil 44 is energised and this causes an arm 42 to engage the end of the lever 35 and this disengages the detent block from the yoke plate 33 and allows the block 18 to rotate. The planes 30a and 30b then become convergent in the opposite direction and the two roller members are urged by the force between the members to roll to the left away from the surface 31 moving the frame 25 to the left against the force of its springs 27. When the upper roller member 13 is clear of the abutment surface 15 the member 10 can move downwardly in the sleeve 11. The lever 35 and arms 32 are spring biased and when the member 10 is restored to its normal position the various parts return to their latching positions automatically. The latch is suitable for use with an electric switch.