The drive release valve diverts the oil flow between the left and right side hydraulic drive motors, and this has an effect on the pulling force. When the valve is open the hydraulic oil flows in series from motor to motor. The wheels roll freely and the loader leaves less tire marks on soft and sensitive surfaces. When the valve is closed, the hydraulic oil flows in parallel between the hydraulic motors on each side, similar to a differential lock in operation. This improves traction and towing capacity of the loader.