Hydraulic and Pneumatic Systems Flashcards

A hydraulic cylinder has a 4-inch bore and the system pressure is 1,000 psi. What is the approximate extension force?

Answer: 12,566 lbf

Force = pressure × area = 1,000 psi × (π × 2² = 12.57 in²) ≈ 12,566 lbf.

Why does a double-acting cylinder retract with less force than it extends at the same pressure?

Answer: The rod reduces the effective piston area on the rod side

The rod occupies part of the piston face, so the annular area on the rod side is smaller and gives less force.

In a meter-out flow control circuit, where is the flow control valve placed?

Answer: In the line leaving the actuator, restricting exhaust flow

Meter-out restricts fluid leaving the actuator, which gives good control of overrunning loads.

A gear pump makes a loud rattling, gravel-like noise and the reservoir oil looks normal. What is the most likely cause?

Answer: Cavitation from a restricted or clogged suction line

A restricted inlet starves the pump, forming vapor bubbles that collapse and cause a gravel-like noise.

What is the main purpose of a pilot-operated check valve in a cylinder circuit?

Answer: To hold a load in position until pilot pressure opens it for reverse flow

A pilot-operated check blocks reverse flow to lock the load until pilot pressure unseats it.

In a compressed air system, where should a branch line be taken off the main header?

Answer: From the top of the header

Taking branch lines off the top keeps condensate in the header from running into the drops.

What is the function of the lubricator in a pneumatic FRL unit?

Answer: Add a fine oil mist to the air for downstream components

The lubricator puts atomized oil into the air stream to lubricate valves and cylinders downstream.