Self propelled lawn mowers use a drive belt much like a riding lawn mower. This drive belt transfers energy from the lawn mower engine to turn the wheels of the lawn mower. This propels the lawn mower forward, which can save your muscles, especially for long uphill treks. Eventually, after many uses, you may need to replace a self propelled mower drive belt. One reason it may need to be replaced is that it became worn and frayed. A belt in this condition will eventually break and your self propelled lawn mower will no longer move on its own.
Disconnect the spark plug cable from the lawn mower. This is a safety precaution that should always be followed whenever you work on your lawn mower.
Remove the cover that is over the wheel drive belt. Depending on your model, it may either be screwed or bolted on.
Push the wheel pulley toward the engine of the lawn mower. The belt should become slack on the pulley and you can then remove it.
Tilt the mower to remove the other end of the belt from the blade pulley underneath the mower.
Install the new belt. First loop it around the blade pulley, and then push the wheel pulley toward the engine and loop the belt around it.
Check the tension on the belt. It should flex about 1/4 inch when pushing on it halfway between the two pulleys. Tighten or loosen the tension adjustment on the wheel pulley to adjust as needed.
Replace the cover and reconnect the spark plug cable.