| 摘要 |
755,124. Switches held set and freed mechanically. MIDLAND ELECTRIC MANUFACTURING CO., Ltd. Feb. 24, 1955 [Feb. 26, 1954], No. 5690/54. Class 38(5) A switch suitable for controlling a threephase circuit and whose cover cannot be removed unless the switch is in the "off" position, comprises a body part 5 of ceramic or other insulating material which has a bore 6 in which is mounted a cam 10 having three equi-spaced lobes 11 which actuates three contact assemblies mounted in the body. An operating spindle 24 has at its inner end a key piece 26 which engages a slot in a block 13 which is attached to the cam by a screw 15 thereby transmitting motion from the spindle to the cam. The contact assemblies comprises spring- loaded resilient blades 18 carrying contacts 19 which co-operate with fixed contacts 20. Fuses 23 connect the fixed ends of the contact blades to terminals 22. Mounted inside the switch cover is a dead-centre snap action mechanism 28 which is actuated by a projection 27 on the spindle. To remove the cover from the switch the key piece 26 must pass through slots 33 in the body 5, and these are arranged to coincide with the "off" position. A back plate 34 has a window 35 through which legend on the cam may be read, thereby facilitating the assembly of the switch. |
