|
The operative mechanism is a toothed collar - about 4" dia - that slides on splines on the axle, in near the transmission. When the collar is pushed toward the transmission the teeth engage in matching teeth on the differential, in effect locking the two axles together. As Parts man says, the pedal operates the linkage. It's clamped to a shaft which has a kind of wedge inside the casting (held on with 4 cap screws). The wedge pushes on a 3/4" rod running in toward the transmission (moves the rod in a half inch or so to engage), that in turn is coupled to the sliding collar with a bracket like the ones operating the transmission speed selection gears. We've had three problems (the third one twice). First, the pedal shaft sticks (with rust) and the clamp on the pedal lets the pedal move without turning the shaft. This is visible from outside. Second, the inside 3/4" rod sticks. Again, rust. The pedal and wedge move, but the rod doesn't. The wedge tries to move the shaft, but the pedal has rotated on the shaft because of the clamp arrangement. It's kind of a safety valve - if it was pinned, the wedge would break. To check, remove the casting and see if you can move the rod toward the transmission with a pry bar. It should move fairly easily - at least a quarter inch, maybe the full half inch if the teeth are lined up. If that works, replace the casting and adjust the pedal so it fetches up solid before the pedal hits the steel foot plate. If the rod won't move, we've had to remove the axle housing to free it up. At this point, ask yourself if you need the lock enough to warrant this exercise! Then try it out. Move slowly forward, turning left or right, holding the pedal down to engage it. It should engage and lock. If the pedal drops to the plate, stop there and re-adjust so you have a quarter inch of clearance. If it doesn't lock, or you feel a bump - bump- bump on the pedal, you have the third problem: the teeth on the collar have been destroyed because somebody tried to engage the diff lock with the wheels spinning, and cut them off. The broken teeth drop to the bottom of the axle housing, and haven't ground anything else up on our machines. If you have this problem, see the question above. Those collars are pricey. A&I distributors have them, cheaper than MF. Good luck - let us know how you make out.
| 
