US Patent 7866420 Track tensioning system for a tracked vehicle

A tensioning system for an endless track of a crawler-type vehicle includes an actuator, such as a dual-acting hydraulic cylinder and piston, which is coupled to a roller to translate the roller into and out of engagement with the endless track to tension or slack the endless track, respectively. The tensioning system has a mechanical stop that limits retraction of the actuator, and thus limits how much slack can be created in the endless track. The actuator automatically adds tension to the endless track when an undertensioned condition is present and automatically removes tension from the endless track when an overtensioned condition is present. To add additional slack to the endless track for removing the endless track for service, repair, or replacement, the mechanical stop may be removed which allows additional retraction of the actuator and thus disengagement of the roller from the endless track.