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 In addition many brakes have electrical contacts which are used in various control functions.
These should be checked to assure proper contact operation, insulation on wire and contacts, and
condition of connections. Many control systems, by design, stop the elevator electrically when it
reaches the floor, then allows the brake to set. This is done to prevent a bump on stopping which
is caused when the brake sets. Brake operation should be checked, where applicable, to see that
this feature is working properly.
2.5.9 Motor-Generator Set
Just as it was previously indicated that it was . very important to check the hoist machine
motor, it is equally important to check the motor generator set. The motor generator set supplies
the varying direct current power to the hoist machine motor and is, therefore, directly responsible
for the elevator performance. Close checks of the bearings, commutator, brushes, windings,
wiring, housekeeping, and mounts should be made.
2.5.10 Operating Speed
The elevator speed should be checked with a tachometer to verify that the elevator is operating
at rated speed. An elevator is designed and manufactured to operate at rated speed. An elevator
operating below rated speed is not providing full service and should be adjusted. Occasionally,
an elevator is found operating over the rated speed. This can result in nuisance shut downs
caused by governor trappings and possible safety applications.
2.5.11 Control Equipment
The A17.2 Manual outlines a complete inspection of the control equipment. A good
preventive maintenance program on the control equipment will greatly reduce shut downs. Many
controllers have pieces of rotating equipment which are in various applications. These should
not be overlooked. They should be given the same type of inspection as the larger rotating
equipment.
2.5.12 Machine Room
The overall machine room should never be overlooked. The A17.2 Manual lists each area to
be checked. It reduces the possibility of accidents and has a direct impact on fire safety. In
addition, the following items should be given special consideration.
a. Proper ventilation is required to keep equipment operating. With the newer type of control
equipment, proper ventilation is even more critical.
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