(i) Electric elevators:
Are provided with a governor on the hoisting motor and guide clamps incorporated in the bottom beam of the car sling. On slow speed elevators, a steel roller between the guide rail and the ends of the bottom beam is used instead of guide clamps. The governor will cut off the power to the motor and apply a brake to the drum.
If the car continuous to speed, another brake which operates directly on the cables, is brought into action. Continued over speed actuates the braking device attached to the bottom beam of the car sling.
(ii) Hydraulic elevators:
ADVERTISEMENTS:
Are held by locked column of oil when the car is at rest. Load brakes are not necessary because a positive check valve is incorporated in the hydraulic system. The standard elevator by laws for electric elevators is not generally required for hydraulic elevators but, of course, can be incorporated if local codes so-designate.