(cont. from previous post) Got the decel/throttle linkage put back together today. Rebuilt the brake unit by putting in new shaft and bushings and brazed up the clevis pin holes to tighten them up. On the bench it seems to work like it should. You can operate the arm by hand on the trottle linkage side and the roller brake gives it a nice drag resistance. If you try to turn the shaft from the other end (governor side) the roller clutch locks it and it can't be turned, even with moderate pressure on a cresent wrench. Here's the problem....I put it back on the tractor, hooked up and adjusted the linkage, and tried out the decelerator. Setting the throttle full open and pressing the decel pedal on 2 or 3 times and the throttle slips back out of position. If I set the trottle any less than full open it won't hold at all when you press the decelerator. If I disconnect the gov linkage and try to make it slip, it won't budge by hand.....hook it back up and it won't hold. Also: The spring unit in the linkage that controls the pedal pressure on the decelerator has been very heavy and wears out your foot if you run it all day. I took it apart and the spring is quite heavy and had about 3" of preload so I found a lighter spring and installed it. That reduced the spring tension by about half which should help with pedal pressure. I don't think this has anything to do with the problem as it should reduce the pressure against the decel brake. Maybe something obvious, but haven't figured it out so far... View attachment Decel.pdf
That linkage lock can be a challenge. Make sure it isn't lubed, might even try sandblasting the inner surface where the rollers ride. Make sure the holes where the roller springs go are clean so springs are free. New springs might help. Later Bob
D6c10K - Did you replace the rollers and the springs under the rollers? This is an important part of reconditioning the throttle hold brake. Also, check the race condition, as Bob says - although I'm not sure sandblasting would be my recommendation, as this surface is required to be smooth for proper brake operation.
I replaced the springs, but not the rollers as they looked pretty good. Didn't replace the plate the springs rest in either and maybe I should have as it had a small amout of wear where the rollers rest. I stoned the roller race with a coarse polishing stone just to clean it up....wan't sure if it needed to be smooth or rough. The thing that puzzles me is you can't make it slip on the bench, even putting a wrench on the arm and pulling on it, but as soon as I hook up the linkages it won't hold at all. The only thing I can think is the weight of the linkage on the throttle end might be just enough to compress the springs and release the rollers' grip. Tomorrow I'll try removing the throttle link and see if it still slips. I may have to replace a few more parts if I can't get it working.
Got the decel working now...took it apart and reground the flat surfaces the rollers ride against. Only took .002-.003 to clean it up. Made a pair of new rollers from 1/2" dowel pins and polised the inside of the hub a little more with emery paper. Works great now. I think the problem was mostly the slight wear on the flat face. Just a little depression, but enough so the roller wouldn't move like it should and wouldn't wedge tight.
Good work. Later Bob