CET Hydraulic Elevator Systems 3

Question 1

What is the function of a hydraulic elevator's anti-creep feature?

Accepted Answer

Automatically corrects slow unintended car movement due to internal valve leakage

Answer

The anti-creep circuit detects slow unintended movement and runs the pump briefly to restore the car to floor level.

Question 2

Which component in a hydraulic power unit prevents the pump from operating against a closed system when the car reaches the top landing?

Accepted Answer

The up-limit switch that de-energizes the pump motor

Answer

The up-limit switch de-energizes the pump motor when the car reaches the top terminal, preventing the relief valve from having to handle continuous full-pressure bypass.

Question 3

Hydraulic oil viscosity MOST directly affects elevator performance by:

Accepted Answer

Altering flow rates through valves, which impacts leveling and ride quality

Answer

Viscosity determines how easily fluid flows through valves and orifices, directly affecting leveling accuracy, speed, and ride quality.

Question 4

When performing a pressure test on a hydraulic elevator, the system pressure is typically held at what level above working pressure?

Accepted Answer

50% above working pressure for 24 hours

Answer

ASME A17.1 requires a pressure test at 150% of working pressure, held for a specified period to verify cylinder and piping integrity.

Question 5

What is the purpose of a silencer or muffler installed on a hydraulic elevator pump unit?

Accepted Answer

To dampen pressure pulsations and reduce noise from the pump

Answer

Hydraulic pump silencers are installed in the pressure line to absorb pulsations that cause noise and vibration in the piping and car.

(CET) Certified Elevator Technician Practice Test

(CET) Certified Elevator Technician Practice Test

CET Hydraulic Elevator Systems 3