The basic principle.
A hydraulic cylinder contains a moving piston or plunger within a pressure-containing body. In lift engineering, “ram” commonly describes the moving plunger or the lifting actuator more generally. Construction and terminology vary.
Pressure acting on effective area produces force. Flow changes the volume inside the actuator and therefore its position. Seals control fluid leakage while guides and bearings support alignment; the lifting arrangement must manage side loads appropriately.
Volume sets ideal travel.
Adding 0.001 m³ of fluid to an actuator with effective area 0.01 m² gives 0.1 m of movement, ignoring compression and leakage.
Follow the relationship.
- Fluid entersInternal volume increases.
- Actuator extendsPressure acts against the load.
- Fluid returnsThe load can lower in a controlled circuit.
Connect it to the lift.
A direct-acting lift uses ram movement directly at the car arrangement. An indirect hydraulic lift uses ropes and pulleys, so ram travel and car travel differ. Telescopic cylinders add further geometry: stage areas and sequencing affect movement.
A closer look
With constant effective area, ideal speed is v = Q/A. This relation needs consistent units and describes the actuator, not automatically the lift car.
Check your understanding
Is ram travel always equal to lift-car travel?
Reveal the explanation
No. Roped arrangements and other mechanisms can change the relationship.