Recent developments in the design of gearless machines for elevators

The authors describe the benefits that have been obtained from a review of traditional gearless elevator machines. Known as gearless machines because of the absence of intermediate gearing, they comprise a motor-traditional DC-driving an integrally mounted rope sheave and are characterised by operating at low speeds-rarely more than 300 rpm-and high torques. They require very large diameter shafts in order to support the elevator system and consequently are generally of massive proportions relative to their output power. Larger sizes need to be mounted on a substantial bedplate, and their weight and size often creates handling problems during installation in the confined space and access to many hotels and office buildings in which they are most commonly used. The review of such a machine has resulted in a modular form being evolved. In this arrangement, the rope sheave is supported within a separate cradle, to which the driving motor is flange mounted