The self-propel system on a Troy-Bilt lawnmower is relatively simple. It uses a small transmission connected to a pulley, which in turn connects to a pulley on the engine’s driveshaft. It uses a small Kevlar belt to connect the two pulleys together. The biggest issue with the self-propel system is belt slippage. Belt slippage shown in the form of the mower lurching forward with the propulsion system engaged. There are a few things you can do to help troubleshoot self-propel system on your Tory-Bilt mower.
Things You'll Need
- Wrench set
- Replacement drive belt
Remove the screws that secure the black transmission cover onto the mower deck. With the screws removed, press in on the sides of the cover and then pull the cover off the mower deck. This exposes the transmission, transmission pulley and drive belt.
Inspect the side of the belt that rides around the pulley for cracking. Severe cracking indicates dry rot. Although you can still adjust a dry rotted belt, it will quickly fall out of adjustment and will likely break if you continue to add additional tension to the belt. If this is the case, skip to step four. Otherwise, proceed to the next step.
Locate the tensioning screw, which mounts between the transmission pulley and the transmission. Turn the screw clockwise one to two turns. Grip the pulley to hold it still and then manually try to pull the belt around the pulley. If it will not pull around the pulley, reinstall the transmission cover and use your mower. If it still lurches, remove the transmission cover again and go to the next step.
Loosen the tensioning screw until you can slip the belt off the transmission pulley. Place the mower on its side so the air cleaner faces upward and then pull the belt through the hole in the mower deck. Pull the belt off the driveshaft pulley mounted between the deck and the mower blade. Place a new belt onto the pulley and then pull the belt though the hole in the mower deck. Place the belt over the transmission pulley and then tighten the tensioner screw until you cannot manually pull the belt around the pulley. Reinstall the transmission cover and test the mower. If the mower still lurches, consult a service center for Troy-Bilt as the transmission is faulty.