One aspect that I had previously inquired about with John Zentmyer is how the pins function within the automatic locker assembly and why they break. The topic came up briefly yesterday and reminded me that I hadn't followed up on it. John and I have had several emails in the past weeks, it surprises me every time he sends me an email unprompted to continue our discussion. Here is his response from today to my question about the pins:
EMAIL 4
Can you explain how the pins function, get loaded, and can break?
RESPONSE 4
The pins were originally called stop pins, and may still be. They prevent (stop) the over-running driver (I don't like the name "cam gear") from rotating past the amount of clearance needed for it to unlock--that is, slightly away from the pinion shaft, so it can be pushed out of the teeth of the coupler (axle gear). In ordinary operation, the stop pins have very little force imposed on them. However, they can break under two conditions: (1) If a small piece of metal, such as a chip off one of the teeth of the drive gears, gets caught between the drivers during uncoupling, the driver associated with the faster wheel can't completely disconnect itself from the coupler, so the turning force is transmitted to the pins and they break, and (2) when climbing up a steep hill with a lot of torque on the axle shaft, if the shaft breaks, its inner end that was under a lot of torque, but isn't any more, snaps the coupler really hard when it lets go. With things whipping around in there the pins will sometimes break.
