Hoist mechanism electric drive - has auxiliary motor with metal rotor sleeve enclosing open-ended chamber

摘要

The system incorporates a main asynchronous alternating-current slipring motor and an auxiliary one with a squirrel-cage rotor coupled to the main rotor, while its stator winding is supplied with variable direct current, or from the A.C. mains for lifting and lowering small loads, its number of poles being less than that of the main motor. The auxiliary motor rotor has a metal sleeve (68) with a hollow chamber (66) inside, open at the ends. The sleeve can consist of a steel tube with copper cladding, there being cooling vanes extending from the cladding inwards into the chamber. Alternatively, the steel tube (62) can enclose a cage (68, 69).