A look inside the Iron Jock 60 centersection reveals another intelligent design characteristic: the oiling system. Notice the two large openings above and below the larger perforation for the pinion gear. These are designed to provide restriction-free passage of gear oil during operation. The way this setup works is trick. Lube oil is pumped by the teeth of the ring gear as the differential rotates. The oil flows up to the front of the pinion housing through the upper passage and into a small reservoir between the two pinion support bearings. Inside the reservoir, the oil pools and is forced through each of the pinion support bearings by gravity. With this arrangement, half of each pinion support bearing is basically submerged in oil at all times. This, in turn, ensures that the bearings stay cool and last a long time.