Lever Judder / Oscillation (Hunting)
Motion that speeds up and slows down rhythmically instead of progressing smoothly, with the boom or bucket bouncing. It typically runs at a few cycles per second and originates either from excessive gain in the control loop, air in the system, or mechanical play.
Eliminating causes systematically gives results far faster than trying random settings. Follow this order:
- Hydraulic side: fluid level, foam in the tank, bubbles in the return line. While there is air in the system, no electronic setting will fix the result.
- Mechanical side: tightness of the mounting clamp, pin play, loose connections. If there is play, the controller always corrects late and too much.
- Control side: is the gain too high, is the ramp time too short, is deadband compensation set too high.
- Signal side: noise on the joystick signal, a worn potentiometer track, a loose connector.
On the tuning side the first thing to try is reducing gain somewhat and lengthening ramp time; these two damp out most oscillations. If the judder appears only at a specific load or a specific boom angle, it indicates you are approaching the system's natural frequency; in that case the solution is to reduce speed or soften the motion in that region.
Where this term is used: Connect Plus and Minus, Run: Installation That Does Not Depend on Technical Staff