Improvements relating to thermally-operated overload relays

摘要

515,602. Thermal switches. DONOVAN, G. O. June 21, 1938, No. 18361. [Class 38 (v)] In a thermally-operated overload circuitbreaker a spindle b carries a screw b' the head of which is gripped by solder in a recess a' so as to prevent rotation of the spindle until the solder has been melted by a heating coil, not shown, carrying the overload current. When the spindle is so freed an arm d, carrying a pawl d' which engages a ratchet wheel b', moves under the action of a spring e to open the contacts. When the spindle b is again held fast by solder, the ratchet mechanism allows resetting. Specification 513,059 is referred to.