I have a Troy Bilt horse that has 2 belts, one for the 2 blades on the deck and a drive belt that runs the hydrostatic transmission.

The transmission belt broke, and I can't figure out how to get to the rear portion of it that changes. I have linked to 2 pictures:

The one with the fain in it is an overhead view below the battery and on top of the transmission on the back of the mower.

The second is the breakout of this section of the parts list.

I need to take the nut on top of the fan off to get the belt around the pully (you can see the bracket that the pully sits "in" in the breakout. I have 2 problems:

  1. How do I get a wrench around the nut above the fan? There's no room.

  2. How do I keep that from turning? I can turn the fan by hand if the brake is on or not, and if the transmission is engaged or not. There is a pull-out lever that disengages the transmission, but that pully always freely turns so when I get a wrench around it I cannot stop the shaft and everything from turning.

How do I do this? Pictures are here:

http://imgur.com/a/N2zA7 and inline

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  • Perhaps you could attempt to install the pulley fan side first.
    – Dan D.
    Apr 30 '16 at 0:07
  • Look at part #57 on that diagram, it's a 3 sided bracket that the pulley sits in, and there is no chance of that belt going around while the pulley is in that thing.
    – mikeb
    Apr 30 '16 at 0:09

It's fairly typical for lawnmowers to have guards like part #57 which make it difficult but not impossible to get the belt on. They're more concerned with making it difficult for the belt to come off. Though, this also helps keep it in place while you fiddle with the other end. You may need to strongarm it a bit, but try to bend them back to the original positions.

If you really want to get the fan off, you need a crow-foot wrench and will probably need to hold the pulley with a strap wrench and work against that. Don't be surprised if it's a reverse thread. The pulley will be splined to the shaft.

I've recently seen a suggestion to hold the pulley by twisting the belt with a flat nail bar. Then put a short 2x4 between the nail bar and frame.

  • That's right, I used a big slotted screw driver to wedge the belt in.
    – mikeb
    May 1 '16 at 13:03

OK, here's how I did it: I put the back on using Harper's method, a slotted screwdriver without taking any of that apart.

For the front, there are 2 pulleys on a shaft coming out of the engine. The top (smaller) pulley is the drive belt and the lower (larger) pulley is the one that drives the deck/blade belt.

This needs to be removed by holding the shaft with a pipe wrench and taking the bolt off the bottom of the bottom pulley.

The belt is a tight fit, and it's worth noting that if you put the brake on one of the small pulleys (#75 in the diagram) pivots and give you enough slack to fit the whole thing properly. So, my steps were:

  1. Remove the old belt (it was broken) and the deck/front belt guide from the mower
  2. Put the new belt around the fan on the back, use a slotted screwdriver to wedge the belt onto the back pulley
  3. Take the front pulley assembly off (it's not on the diagram posted)
  4. Put the belt around the front pulley and re-attach the assembly
  5. Put the "parking" brake on and route the belt properly
  6. Re-assemble everything.

On a Horse XP there is only one drive pulley. The fan will come off using a couple shots using an impact with a 3/4 short socket. If you cant get the fan to clear the shaft; it does. To get it out of the way just enough take a big ass screw driver and bend the tabs down, then put the belt on and bend them back.


i couldn't do what was suggested. you have to remove the fenders and battery box top to get to the fan. i bent the belt guard bracket tabs out took off the old belt replaced it w new belt and bent the guard tabs back.

  • check both idler pulleys that are close to the fan..... if they need replacing ,now is the time to do this
    – user125879
    Nov 18 '20 at 11:41

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