Maintenance safety lock for ski lift - has switch locked by key and relays opened by impulse from magneto operated by repair personnel

摘要

The safety lock is fitted to a ski lift to permit maintenance without danger to personnel. It comprises a double switch (30a, 30b), locked in the maintenance position by a removable key. On arrival at the repair area the maintenance fitter uses a magneto or provide an impulse between two points (2, 5). This closes a contact (33a), and operates a relay (31), and an associated contact (31a), this latter contact breaks the supply to the ski lift drive motor, preventing its operation. To reset the key-operated switch is unlocked and another relay (32) remakes the motor supply.