Some popular Belt Routing Diagrams
Installing a new belt on a mower deck can be confusing at times.
We've gathered here a few pictures of different deck belt routing patterns.
Transmission belt routing chart. Note that idler pulley # 21 is a "Flat Idler" and # 22 is a "Grooved Idler". When
figuring the routing pattern for your machine, keep in mind the difference between a flat pulley and a grooved
pulley. Also note that the belt should NEVER be so long that it touches itself like it seems to be doing around idler #
21 in the picture. Also be careful to route your belt INSIDE the metal guides (# 13 & # 17) when installing your belt.
Two popular MTD belt routing diagrams. Note that the idler pulley in the left hand chart would be a "Flat Idler",
meaning that the back of the belt rides against the pulley and the blade pulleys are "Grooved Pulleys"
designed to contact the inside of the belt.
Here are a few examples of John Deere belt routing diagrams. The one on the left is for a front mount mower deck.
A few more examples of different belt routings. Make sure the belt doesn't rub against anything
before you tighten everything. Again, it's worth the time to study what is a flat pulley
and what is a grooved pulley and how they interact with the belt.
Small Engine Parts Specialists