Pneumatic Systems Flashcards

How does a pneumatic cylinder cushion work?

Answer: It traps exhaust air near the end of stroke and meters it through an adjustable orifice to decelerate the piston gradually

End-of-stroke cushioning uses a cushion spear or piston nose that enters a cushion seal near the end cap, trapping the remaining exhaust air. This trapped air is forced through an adjustable needle valve, creating a controlled deceleration of the piston before it reaches the end cap.

What is the purpose of a pneumatic timer valve?

Answer: To create a time delay in a pneumatic circuit by slowly charging or exhausting a small reservoir through a needle valve

A pneumatic timer valve creates a timed delay by using a needle valve to slowly fill or empty a small air reservoir. When the reservoir reaches sufficient pressure, it shifts a valve or sends a pilot signal, introducing a time delay in the circuit sequence.

What is a vacuum generator (venturi) and how does it work in pneumatic systems?

Answer: It uses compressed air flowing through a venturi nozzle to create suction (vacuum) for gripping and holding applications

A pneumatic vacuum generator uses the Venturi effect — compressed air flowing through a constriction creates a low-pressure zone that generates vacuum. This vacuum is used for suction cups, material handling, and pick-and-place applications.

What is the effect of oversizing pneumatic lines and fittings?

Answer: Lower pressure drop but potentially higher installation cost with no additional benefit beyond the optimal size

Oversized lines reduce pressure drop, which is beneficial up to a point, but beyond the optimal size, the additional cost of larger fittings and tubing provides no meaningful improvement in performance. The extra volume can also slow response time.

Why should thread sealant tape (PTFE tape) be applied carefully to pneumatic fittings?

Answer: Because loose tape fragments can break off and enter the system, blocking orifices and damaging valve seats

PTFE tape must be applied neatly, starting 1-2 threads back from the end, wrapped in the correct direction, and trimmed cleanly. Loose strands can shear off during assembly and enter the air system, blocking small orifices in valves and instruments.

What is the function of a soft-start (slow-start) valve on a pneumatic system?

Answer: To gradually increase air pressure to the system during startup, preventing sudden uncontrolled actuator movement

A soft-start valve slowly ramps up the air pressure to the downstream system during startup, preventing cylinders and actuators from making sudden, uncontrolled movements when the system is first pressurized — an important safety feature.