A knuckleboom loader for processing trees includes a delimber, an actuator, and a hydraulic arrangement. The delimber includes a knife. The actuator is coupled to the knife and is operable to move the knife. The hydraulic arrangement includes a fluid, a tank, a pump, and a valving arrangement. The tank is configured to store the fluid. The pump is in fluid communication with the tank and is configured to supply fluid from the tank to the actuator. The valving arrangement is located between the pump and the actuator. The valving arrangement is operable to regulate a flow of fluid from the pump to the actuator, and from the actuator to the tank for opening and closing the knife relative to a trunk of a tree.
