Fault Phenomenon: Schaeff rough terrain forklift when driving on muddy ground, pressing the differential lock button, the differential lock does not engage, wheels spin.

Troubleshooting Process:
– Checked differential lock cylinder: cylinder not actuating.
– Checked air lines: air line leaking.
– Checked switch: switch failed.
– Checked gear sleeve: gear sleeve worn.

Root Cause: The differential lock cylinder seal failed, resulting in insufficient thrust.

Required Parts: Differential lock cylinder repair kit.