I've taken apart the motor kindly sent to me by Dynascope yahoogroup member George A. (see msg. #7732). I got the motor without the reduction gear train. I've skipped getting to and removing the pinion gear for the moment. I'm more concerned about the steps required for the actual reversal.
I was able to disassemble the motor without using special shop equipment. The most "special" tool used was my Moto-Tool, which I firmly believe every fellow tinkerer should own. An inexpensive gear puller used by slot car hobbyists is ideal for removing the main rotor pinion gear, a necessary step in gaining access to the motor.
Pictures are clickable for larger view
Note: The discussion below assumes some of the fixed parts below the spinning rotor must be moved or flipped. I really don't know if that's true. It's entirely possible only the spring and/or it's missing part must be replaced in order to reverse the motor direction (best case). Worst case is having to deal with the hub as described.
There are two areas of concerns as to whether this motor can be readily reversed. First, I'm pretty sure something is missing from the area where the motor shaft attaches to the rotor. Second, getting the spoke type stators out was difficult to do without warping them. I can see how it was easy for Synchron to install them with a press, but going in the other direction is tough, especially with the second stator since there is little to grab. The problem is the central hub is ever so over-sized, intended to allow a snug fit for the topmost stator.
I have some pictures and detailed comments:
This picture was taken just after I removed the first of two similar spoke stators. This was easy. But then a small spring fell out from somewhere. It is seen on the lower right. (ignore the squiggly line at the upper left, it's just ink) Apparently, the spring was floating around loose. (see close-up picture#2 below) I am 100% certain the spring was not on the shaft when I first removed it. I expected to find a start direction bias spring or other arrangement but nothing was there.
This spring concerns me. From what I know about synchronous motors, it's common to use a spring as a kind of bias device to allow the motor to start in only one direction. Without the spring, at startup, the motor can go in either direction. The spring is slightly enlarged but it has a definite hook on one end and the long side looks like it should be resting somewhere. After taking the entire motor apart, it seems the spring needs a missing part that holds it in place and possibly also serves as a bearing/spacer, probably where the shaft and rotor come together.
Here's a close up of the spring:
Picture # 2The other potential problem was getting the stator parts out. They are pressed on to the stationary center hub. The upper stator came off quickly with no damage. The others required quite a bit of fiddling until I realized the hub is slightly oversize near the top where the fist stator sits. The others, further down the hub are quite loose, but jamb when an attempt is made to go up and past the top of the hub. I ended up using my moto-tool to shave down the hub enough to pop off the lower stators. If I were to take apart another motor, I'd first make a tool that would evenly shave down the hub, probably 0.001 or so. I took a few pictures that help indicate where the high spot is:
Picture # 1 above shows the first stator removed and the space it occupied on the hub is visible. Picture # 3 below shows how the second stator is nearly where the upper stator sits. It is stuck on the high spot that serves to hold the upper stator in place. Note: Trying to twist and turn the stator up past the high spot does not work, believe me I tried. The high spot needs to be mechanically reduced.
Picture # 3
Picture # 4 shows how mangled the middle stator got. This part was the most difficult to remove because there is little room underneath to pry upwards and barely enough room to shave down the hub. The good news is these parts are soft enough to be hammered/bent flat with little risk of breakage.
Picture # 4Picture # 5 shows how I popped off the lower stator after I shaved down the hub with my moto-tool. These are classic Sears craftsman screwdrivers, nothing breaks them, but this was not the ideal way to do this. If I were going to do this again, I'd consider using a small gear puller and reshaping the teeth so they'd fit close to the hub, allowing an even pull and reducing the chances of bending the stator.
Picture # 5Picture # 6 shows the cover over the coil. It is also held in place by the hub and comes off with no difficulty. The aluminum wave weaving around the vertical poles along with the outer case shell both slide up and off with no difficulty. Contrary to appearances the case shell is not attached to the pear shaped gear housing. The vertical elements are actually fingers that are part of a flat plate with a center hole at the base of the hub. That plate is actually the base of the motor. The pear housing is spot welded to it.
Picture # 6Picture # 7 and # 8 show the cover removed and the coil exposed. Note: The hub has no moving parts.
The coil appears to be a simple one direction winding of fine wire (under the tape).
Picture # 7 Picture # 8
Picture # 9Picture # 10 is of the rotor and shaft. The pencil points to where I believe the spring goes. I couldn't focus closer but there is a small nylon hub that looks like a place where a part that holds the spring might go. The spring by itself has nowhere for it's hook to go and nowhere to exert rotational resistance. I'm familiar with springs like this. I worked with these when I was at IBM.
Picture # 10
Once I work out the details mentioned above, I'll put everything in a more step-by-step order. I need to take more instructional type pictures as well.
