How do hydraulic cylinders compare to hydraulic motors in terms of motion and oil consumption?

• A. Cylinders produce linear motion and consume oil only while moving; motors produce rotary motion and consume oil continuously.
• B. Cylinders produce rotary motion and consume oil continuously; motors produce linear motion and consume oil only while moving.
• C. Cylinders and motors both consume oil continuously while operating.
• D. Cylinders consume oil only when idle; motors consume oil only during startup.

Answer: (A)

The way hydraulic energy is used depends on the motion produced. A hydraulic cylinder is a linear actuator: pressurized oil pushes the piston to move in a straight line, and once the piston reaches its limit and the flow is blocked, the oil flow stops apart from small leaks. So oil is consumed mainly during movement, not while the cylinder is idle.

A hydraulic motor, on the other hand, turns hydraulic energy into rotation. To keep the shaft turning, the motor requires a continuous flow of oil to supply torque against friction and maintain motion. Therefore oil flow continues for as long as the motor is operating, with a small amount of leakage still present when stopped.