Abstract: A differential lock control system controls a hydraulically-operated differential lock via a solenoid valve. Energization of the solenoid valve is controlled by a circuit which includes a normally closed latching relay, a normally open relay and a pair of operator-controlled momentary contact switches. The control circuit further includes a pair of steering valve-operated switches coupled in parallel and to the normally closed relay. Each steering-operated switch is formed by a conductive plunger which is grounded by the steering valve housing whenever the steering valve spool is moved to the end of the valve bore to compress a resilient and electrically insulating O-ring interposed between the plunger and the valve spool.

Abstract: A tractor transmission is provided with a clutch housing containing an oil reservoir vented to the main transmission which is vented to atmosphere. A transfer pump is disposed in the clutch housing to pump an oil-air mixture from the reservoir to the main transmission housing. A portion of the pumped oil-air mixture is diverted through a line of a predetermined size to lubricate the front differential. When the oil reaches the front differential, it is diverted to the left and right final drive gear spaces separated by left and right walls from the differential gears. The oil in the final drive spaces increases in height until it passes through either the bearings supporting the differential housing or through the center of the differential pinion gears to the differential gear spaced. Holes in the left and right walls provide maximum levels of oil in the final drive spaces.