I have a Case M160 belly mower under my Case 1120 compact tractor. I bought the whole rig second (or 12th) hand and have spent much of the last 2 years maintaining it. There always seems to be something wrong but it does seem to be gradually improving.
The latest problem is the drive pulley on the mower falls off. I have an "Operators Manual/Parts Catalog" for the mower. I think I am doing everything correctly but everytime I put it back together it just falls off again. I can't see what is supposed to keep the pulley on.
The shaft from the gearbox has a spline with a semi-circular key that fits in it. This fits into a spline in a "bushing" (part# 1993037C1). The bushing is tapered on the outside so that the pulley press fits around the bushing, then there are 3 set-screws that thread in between the pulley and the bushing. The manual indicates that the set screws are to be torqued to 14 ft-lbs.
The manual says:
Install drive pulley (2) with split tape bushing (1) on gearbox vertical shaft. Make sure key (4) and keyways are aligned.
Position centerline of drive pulley (2) 15/16" (plus or minus 1/32") above mounting surface of gearbox stand (3) as shown. This is a very critical dimension and must be held. Alternately tighten split taper bushing set screws to 14 ft-lbs. Check mounting distance to make sure it is correct.
I've tightened those set screws as tight as I can but the pulley/bushing combo just falls off as soon as I put power to the mower. It isn't obvious to me what is supposed to hold the bushing on. Just squeezing the shaft? The set screws don't seem to be trying to tighten the bushing at all...they don't look like they are tapered and in any case they bottom out before they put much pressure on the bushing to tighten. Maybe they are trying to move the pulley itself up the taper and thereby squeeze the bushing? In any case it isn't working because the whole thing is falling off again.
I would try buying a new bushing if I could find one but my searches indicated that the part number was replaced, and that neither the original part, nor the replacement part is available any longer. But the bushing (although not pristine) looks like it is in reasonable shape.
Anybody have any thoughts on this?