I figured out how the locking mechanism worked on the unit. The split ring at the back acts like a spring to push the spindle forward in the housing, keeping it in place normally. The ring is stationary and has a thin bearing material between it and the spindle. It rests in a relieved area of the housing with a tapered landing on the very back edge of the housing. The back edge of the ring is tapered also. These tapers are shown in the first photo. The tapered part of the ring rides along the tapered part of the housing, pushing the ring forward against the spindle by the force of the ring trying to expand. Where the ring is split, it has a taper on each side, as shown in the second photo. It turns out if I spread the ring apart even slightly it locks up the spindle. And I bet the wedge shaped split is a clue. So the part that is broken off held some mechanism that when turned pushed a wedge into the tapered split of the ring, spreading it apart a little more, and locking up the spindle. I could make a piece that completes the threaded hole and reinforces it well. Then make a fitting that screws into the hole that has fine threads on the outside and has a plunger inside that has a taper on the end that fits into the tapered split in the ring and sticks slightly above the top end of the fitting. Then a knurled cap that screws onto the fitting can be used to push the plunger down and lock the spindle, as shown in the third photo.
I also figured out how to take it apart! When I looked at the diameters of the spindle at the rear, the spindle in the front and the worm gear inside. The spindle diameter at the front was smaller than the worm diameter and the spindle diameter at the rear, so I figured the spindle must come out through the rear. And I figured the split ring must be small enough an OD when fully compressed to fit through the ID of the housing at the rear. Sure enough it started pushing on a collet inserted into the front the ring started to compress and eventually started to come out of the end of the housing. I stopped when it was out just past the taper and made a ring out of a piece of pipe with an ID a few thousandths smaller than the ring diameter at that time, and set it against the ring to support the housing and to capture the ring. Then continued to push out the ring. It came out fine and when completely out, the spindle came out freely. I say freely, it is a
very close fit into the housing.
So now if I wanted I could braze in a new piece to the housing but I don't think I want the heat on it so I'll try the reinforcing ring and screws bit to attach a new part to it. Here are the pieces. The collet nut runs on a set of ball bearings. And under the paint is a nice coating of black filler, so this isn't a cheap unit. It has a quality paint job, which I've messed up now looking for pins holding the spindle in place, so now I have to redo. The fit of the spindle into the housing is
very, very fine! There's a taper at the front inside of the housing and the spindle to center it and align it. That also makes it lock up easier when the split ring pushes it forward. Since the spindle is held in position by the spring force of the split ring, it's definitely a light duty unit. The ring at the lower left corner of the last photo is what I made to capture the split ring.
Irby
