What does ramp time change in hydraulic motion?
A ramp is a transition curve placed between the joystick output and the valve input: when the command changes abruptly, the valve follows it gradually over the set time rather than all at once. It is the simplest and most effective acceleration control method for preventing the hydraulic shock and load swing that occur when the operator pushes the lever hard.
The ramp is set in both directions. Ramp up smooths acceleration, ramp down smooths deceleration and stopping. On a boom or a lifting arm, a long ramp down is often more critical than ramp up because it prevents the load lurching forward at the moment of stopping.
Typical problems the ramp solves:
- Pressure spike in the cylinder and hose jerk when the lever is pushed suddenly.
- A suspended load starting to swing at the stop.
- The pump bogging down and losing speed under a sudden flow rate demand.
The cost is cycle time. Too long a ramp makes the machine feel sluggish; the operator notices the command being applied late and starts overusing the lever, which in turn produces overshoot. The practical approach is to choose the shortest ramp at which the load swing visibly disappears.
The ramp also has a hydraulic limit: pump flow rate, hose volume and oil compressibility already provide natural smoothing. On very small cylinders the ramp is barely noticeable, while on long booms its effect is pronounced.
Full coverage of this topic: The Importance of Hydraulic Control: Why Should It Be Commanded by an Electronic Signal?