Patent GB-112667-A (GB)
Title: Improvements in Electric Switches.
Inventor: HOEHN KARL
IPC: H01H73/42
Filed: 1917-01-19
Abstract: 112,667. Hohn, K. Jar.. 19, 1917. Automatic circuit-breakers &c.-In an automatic circuit-breaker for electrical apparatus, a snap releasing-member 6 rotatably arranged upon the handle or switch shaft is connected to a member 2 upon the handle shaft by a spring 3 which is tensioned as the switch is closed, the parts being retained in the closed position by a locking-device 16 - - - 19 which, upon overload &c, is forced out of action by the swinging round of the releasing-member under the influence of the tensioned spring. As the switch is closed by turning the handle, the releasing-member follows the part 2 until it is prevented from further movement by a catch 12, and a pawl 8 then carries on a member 15 upon the switch shaft 14. As shown in Figs. 2 and 3, the apparatus has a starting-switch 31 and this is closed when the roller 17 of the locking-device engages with the hollow 22 of the part 2. By a jerk of the handle at this position, the roller is forced out of the hollow 22 and drops into a notch 29 in the part 2 and behind a shoulder 30 on the member 15, so that the switch and part 2 are locked together and retained in the normal running position of the switch. In the event of overload &c, a trip coil 32, 41, or other control device actuates mechanism 34 - - 38 for with. drawing the catch from the path of the releasing- member which, under the influence of the spring 3, swings round and forces the roller 17 out from engagement with the parts 2, 15, so that these parts are released to be returned to normal position by spring 3 and the weight of the handle or another spring, and by a spring 23, respectively. As the releasing-member swings round and the parts 2, 15 move back in; the opposite direction, a cam surface 40 upon the releasing-member passes under the pawl 8, and raises it out from engagement with the shoulder 13 of the switch member 15; in this way, the parts 2, 15 are disconnected from one another so that the switch is opened even if the handle is locked or retained in the ' on ' position. The part 2 may be formed in one with the handle shaft which may be recessed to accommodate the end of the switch shaft, and if a starting-switch is not provided, the hollow 22 upon the part 2 may be dispensed with. Moreover, if a free handie is not desired, the handle may be mounted directly on the switch shaft and the part 15 be dispensed with, a toothed member being mounted on the shaft and connected to the part 2 by a spring for providing a shoulder in line with the notch 29 for the roller 17 to bear against, and also for permitting of the switch being opened by turning the handle, in addition to the automatic release by the member o. Switch mechanism interlocking with lids.-For providing interlocking means between the switchbox door and the switch mechanism, catches 42, 43, Fig. 2, are fitted inside the box and door in such a manner that, when the door is open, the catch 42 engages with the notch 29 and prevents closing of the switch, whereas, when the door has been shut and the switch moved partly or wholly towards the closed position, a rim 27 upon the part 2 prevents the disengagement of the catch 43 and consequently the opening of the door.