Patent GB-934797-A (GB)
Title: Push-button mechanism
IPC: H01H27/08
Filed: 1960-10-05
Abstract: 934,797. Locking switches. BROOKHURST IGRANIC Ltd. Oct. 5, 1960 [Oct. 23, 1959], No. 34126/60. Class 38 (5). [Also in Group XXV] A push-button mechanism comprises a lock-barrel 14 rotatably mounted in a reciprocable push-button 12 and rotatable upon insertion of a key from a first position to two other positions, and a latch member 20 mounted for rotary movement derived from the lock-barrel and for axial movement derived from the push-button and formed so that in the first position of the lock-barrel the latch member is free to be axially reciprocated by movement of the push-button and so that in either of two opposite extreme axial positions of the pushbutton and when the lock-barrel is rotated to a respective one of said other positions, said push-button is prevented from moving axially. In the construction shown, the push-button is cylindrical and is mounted for reciprocal non-rotatable movement in the bore of a tubular casing 10, a spring 18 disposed in the casing biasing the push-button to the outwardly extended position. A shaft 22 is axially disposed in the casing and non-rotatably secured to the lock-barrel and an operating member 24 is rotatably mounted on the shaft and non- rotatably guided in its casing for reciprocal movement by corresponding movement of the push-button. The latch member 20 is mounted on the shaft for rotation thereby in response to the rotation of the lock-barrel. The casing is provided with ribs 10g, 10j which guide the operating member and prevent its rotation and the ends of the ribs 10g provide portions which engage with the latch member to prevent movement of the push-button in the other positions. As shown, the latch member is provided with notches 20d and when these are aligned with the ribs 10g the push-button can be moved inwardly ; this condition applies when the lockbarrel is in the first position. When the pushbutton is in its outward position the lock-barrel can be rotated 60 degrees counter-clockwise, as shown in Fig. 3, and a flange 20b of the latchplate then engages with the upper ends of the ribs 10g to prevent depression of the pushbutton ; rotation of the latch-plate is limited by engagement with ribs 10h. When the lockbarrel and latch-plate are in the first position if the push-button is depressed and the lockbarrel is then rotated 60 degrees clockwise, the flange 20b of the latch-plate engages the lower edges of the ribs 10g and hence the push-button is locked in its depressed position. In each of the three positions the lock-barrel is locked in position when the key is withdrawn by plungers 14d which engage between pairs of ribs on the push-button. In a modification the latch-plate instead of being rigidly secured to the shaft 20 as in the above embodiment is connected to it by means of a torsion spring. The shaft has a clutch-plate rigidly secured to it which is provided with a lug which protrudes through a slot formed in the latch-plate. This construction permits the lock-barrel to be rotated 60 degrees clockwise while the push-button is in its outer position without movement of the latch-plate, such movement however stresses the torsion spring and when the push-button is depressed and the latch-plate becomes free of the ribs 10g the latch-plate then rotates through 60 degrees under the urge of the spring and locks the push-button in its depressed position. The push-button can be depressed in the first position of the lock-barrel as in the previous embodiment and the lock-barrel can be rotated counterclockwise to lock the push-button in its outer position also as in the previous embodiment. The push-button adapted to operate an electric switch and to allow the switch to be positioned in positions 90 degrees apart relative to the operating mechanism ribs 30 degrees apart are provided on the interior of the casing to locate the push-button ; thus the push-button can be placed in positions 30 degrees apart during assembly. Specification 833,435 is referred to.