Describe gearless traction elevators.
What will be an ideal response?
The traction sheave and brake are mounted directly on the motor shaft. The speed of rotation of the traction sheave (which contains the wire rope) is the same as the speed of the motor. The speed can be varied by using a DC electric motor built to run at the speed required. Car rise speeds can range from 500 to 1200 ft. /min. (152 to 366 m/min.). Gearless elevators can also be operated using a motor generator drive. The range of lifting capacity is typically from 2,000 to 7,000 lb. (900 to 3,150 kg). The hoisting mechanism is normally housed in a penthouse on the roof.
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Spark ignition is important for roof top or package units located outdoors because of ____________________ problems.
Fill in the blank(s) with the appropriate word(s).
P = 600,000(0.10)(P/F,10%,2) + 1,350,000(0.10)(P/F,10%,5) = 60,000(0.8264) + 135,000(0.6209) = $133,406
What will be an ideal response?
The ____ is a form showing a number of bar diagrams with letters substituted for dimensions.
A. reinforcing bar schedule B. rebar schedule C. coded bar schedule D. orthogonal schedule
What is the difference between a contactor and a motor starter?
A) Motor starters are only used to start the motor, contactors are used to keep it running. B) A motor starter has built in overload protection. C) They are two names for the same thing. D) Contactors will not operate a motor.