CET Elevator Installation & Components 3 — Questions and Answers
Question 1: What is the primary purpose of elevator buffers located in the pit?
- Support the guide rail base clips
- Absorb and dissipate kinetic energy if the car or counterweight overruns the terminal landing (Correct answer)
- Prevent hydraulic fluid leakage
- Anchor the compensation chain
Correct answer: Absorb and dissipate kinetic energy if the car or counterweight overruns the terminal landing
Buffers (spring or oil type) are designed to decelerate and stop the car or counterweight in the event of overtravel beyond the terminal landing.
Question 2: What is the function of the car sling (frame) in an elevator installation?
- Encloses the passenger cab interior
- Carries the suspension ropes and transmits loads to the car platform and safety device (Correct answer)
- Houses the door operator motor
- Connects the governor rope to the car
Correct answer: Carries the suspension ropes and transmits loads to the car platform and safety device
The car sling is the structural steel frame that suspends the car platform, mounts the guide shoes, and incorporates the safety device plank.
Question 3: In a 2:1 roping arrangement, how does the rope speed compare to car speed?
- Rope moves at twice the car speed (Correct answer)
- Rope moves at half the car speed
- Rope moves at the same speed as the car
- Rope speed varies with load
Correct answer: Rope moves at twice the car speed
In a 2:1 roping system, the sheave on the car or counterweight acts as a movable pulley, so the rope must travel twice the distance the car travels.
Question 4: What type of safety device is activated by the governor and clamps the guide rails to stop a descending car?
- Electromagnetic brake
- Progressive or instantaneous safety (Correct answer)
- Pit buffer
- Pawl device
Correct answer: Progressive or instantaneous safety
Governor-operated safeties (instantaneous or progressive type) grip the guide rails and bring the car to a controlled stop when overspeed is detected.
Question 5: What is the purpose of compensation ropes or chains in a high-rise traction elevator?
- Limit hoistway door travel
- Compensate for the changing rope weight imbalance as the car moves through its travel (Correct answer)
- Act as a secondary suspension system
- Balance hydraulic pressure fluctuations
Correct answer: Compensate for the changing rope weight imbalance as the car moves through its travel
As the car rises, the hoist ropes on the car side become shorter and heavier on the counterweight side; compensation ropes hang below both to equalize this imbalance.
Question 6: Which ASME code governs the installation and inspection of elevators in the United States?
- ASME B30.2
- ASME A17.1 Safety Code for Elevators and Escalators (Correct answer)
- ASME B31.1
- ASME A13.1
Correct answer: ASME A17.1 Safety Code for Elevators and Escalators
ASME A17.1 is the primary U.S. safety code covering the design, construction, installation, operation, inspection, testing, maintenance, and repair of elevators.
Question 7: What is the role of the deflector sheave in a traction elevator machine room?
- Measures hoist rope tension
- Changes the direction of hoist ropes to achieve proper wrap angle on the drive sheave (Correct answer)
- Regulates motor speed
- Supports the governor rope
Correct answer: Changes the direction of hoist ropes to achieve proper wrap angle on the drive sheave
The deflector sheave redirects the hoist ropes from the drive sheave to the counterweight, ensuring proper rope fleet angle and traction sheave contact arc.
CET Elevator Installation & Components 3
What is the primary purpose of elevator buffers located in the pit?