I have an update on the culvert loader function that I'd like to share.
Even after changing the position of the microswitch...a MAJOR improvement in the culvert drop alignment...the trolley seemed to have some hesitations as it transversed the beam, principally on the return to the pick-up (home, in my terminology) position.
I thought it had to do with motor drive itself. But, I discovered yesterday that the motor drive unit has little to do with this hesitating motion. I found that out by removing the motor drive altogether....the four screws on the upper bracket removed, the drive can be extricated from the trolley on the beam.
So with the trolley, containing the two claws that retrieve the culvert, free to be moved manually on the beam, I could definitely feel the localized resistance at the same spots as under power. And what I discovered was that it had to do with the bottom external surface of the beam, not any of the internal surfaces of the beam. The claw trolley has a couple of small spool-like wheels with a coil spring on each that bears against this bottom beam surface.
The springs on the spools have tangs which necessarily bear against the beam to provide some resistance to the claw trolley motion as the motor drive reverses direction (return to home, dropping the culvert into the car). It seems essential that the motor drive move on this return before the claw trolley moves, a relative motion which actually results in the claws releasing the culvert to drop.
So it seemed that the spring tangs on the two spool wheels were simply sliding on the bottom beam surface, but not smoothly in certain spots. So I decided to do two things: Clean and polish the bottom external beam surface to get rid of any roughness, and then lubricate this surface. Here's what I did...
I first simply cleaned the bottom beam surface with a bit of isopropyl alcohol. Then I polished the surface using a set of six polishing cloths I have with abrasive values ranging from 3200 to 12,000....just a few strokes with each cloth in sequence. (I typically use them to remove light surface scratches). Just running my finger along that bottom surface after doing that I could tell I had made a SIGNIFICANT difference in the surface feel, and I did NOT feel the same resistance/hesitation to the trolley as I manually slid it along the beam.
But for good measure I did one more thing: I lubricated the surface. Not with oily grease, but with plain ol' graphite. I put some graphite powder on a cloth and rubbed it over the surface. Then the trolley seemed to move even more smoothly along the beam.
So, I replaced the motor drive unit and cycled the action. A-B-S-O-L-U-T-E-L-Y no hesitation as before. Smooth operation in both directions. Correct, repeatable culvert drop.
Time will tell, of course, but I certainly feel the effort was worthwhile. Perhaps a periodic application of some graphite might be in order....just as is recommended for other accessories, such as those having the solenoid drive motor with the rubber washer having angled nubbins. We'll see.
Thought I'd share my own results, though. Simple to do.