Wednesday, April 16, 2014

MTD 12B-443F500 V-Belt Replacement

What the operator's manual for the subject machine tells you about v-belt[1] replacement is nonsense -- it can't be done that way.

Here's a view of the v-belt on the transmission's pulley.

The manual tells you to loosen off that big screw toward the lower left of the photo to release the tension on the belt. That doesn't work. The screw is not a belt-tensioning screw. (Even if it were, there isn't enough travel in the belt tensioner to ever permit the belt to be slipped off over the pulley's upper flange.)

Note the two screws[2] in the pulley's upper flange. There's a reason for those -- the screws make it possible to remove the pulley's upper flange so that the v-belt can be removed and replaced.

To get the flange off, you need a No. 2 Pozidriv[3] screwdriver and an 8mm open end wrench. (The wrench is for two ny-lock hex nuts underneath.) Here's a view of the pulley with the upper flange removed. (The rest of the pulley is pinned to the transmission's input shaft; it never needs to be disturbed.)

Now the belt can come off for replacement.

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I suppose the lesson here is, "Don't be surprised when you encounter utter hogwash in a technical manual." A lot of technical instruction seems to have been written by people who've never been inside the same building with whatever they've written about.

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[1] The belt is MTD P/N 754-0637A. I'm not absolutely certain, but it looks to me like a common 3L310 v-belt. (3/8" across the wide top of the belt; 31" overall length.)

[2] The screws are M5x16mm pan head.

[3] See this post for some information on Posidriv.
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