Model 40601B riding lawn mower-need tension pulley spring

Question edited for clarity. I have removed all the information that isn't needed.
Question moved from Cars and Trucks.

The answer is the same as it was yesterday.

All Ride on Mowers have a tensioner for the belt. Some have a spring operated idler pulley, some have bolts you slacken and physically move the drive pulley in tracks. One you have the belt correctly tensioned, you tighten the bolts.

Look at the videos

Jim, Double check to make sure you have correct belt for the deck and are installing it in the correct configuration as per manual or drawing on deck. Very few lawn tractors have deck belt adjustment, most do not, most deck belts have a spring loaded tensioner to take up the slack.
This could be some of your problem, the tensioner/idler pulley sometimes seize up and must be lubed up till they move freely, or your belt could be loose. Look in your manual or try google searching your make, model #, deck belt adjustment.
How to Change Riding Lawn Mower Deck Belt

Mower belt tensioner repair question to the Garage Gang

lawn mower deck belt routing Google Search

Your deck should have a couple "idler" pulleys on them in addition to the main mandrell pulleys that have tension on them via springs to keep tension on your deck belt. Maybe you need to really examine the condition of those "idler" pulleys and also the main pulleys to find the problem.

There are four pulleys on the deck. Two for the blades, one idler, and one tensioning. The two smaller ones are the idler and tensioning. The tensioning is the one on the right. The post coming out the top of the pulley is where the spring goes, it slides over the top and a clip goes throught the hole at the top of it to retain the spring.

I hope this helps.

without being there, I am guess it is the tensioner pulley spring, it is in the middle of the deck and hooks to that pulley and then there is a metal brace with a hole in it, the spring is heavy duty if this is the spring, you will need to pull/pry on that pulley once the spring is connected, you may want a ratchet strap, but once the belt is on an you release the tensioner pulley it will tighten up the belt. Good Luck Tim

this thread might help if I confused you:

http://www.howtomendit.com/answers.php?id=142623

There is no adjustment on the Craftsman mower belt tension. The tension is maintained by a spring. If the belt is to loose you either have the wrong belt or something is broken like a mandrel housing that holds the fixed pulleys in place.

There is no tension adjustment it has an idler pulley working off from a spring. Check to make sure that the spring did not come off or break. If neither of these have happened then the belt is stretched and you need to purchase a new one.

There is rarely any adjustment to tighten the belts on a riding mower. The belts are tensioned by an idler pulley which is controlled by a idler pulley spring. Almost all riding mower belts must be accurate to the hundredth of an inch or no less than accurate to 1/8th inch. It is very rare for a belt to be in full inch increments. This is why automotive or general purpose belts will not work on a riding mower. I know it is tempting to try to get by with a $10 belt rather than spending $35 or more for the correct belt. Trust me, you will only waste your money trying to get by with the inferior belts. Riding mower belts and extra heavy duty and generally will not stretch at all. Generally they will have 5 or more strands of a Kevlar type material so that stretching is virtually non existent. If the belt will not tighten then it is most likely not the correct belt. If the belt is in fact the proper belt and still is too loose, then you should look for pulley wear or weak tension springs. Metal pulleys do wear and tension spring do loose tension.

Remember the belt rule, V of the belt goes in V pulleys.Flat pulleys that are stationary or move get the back of the belt. You can figure it out. Its not rocket science. Remember at some point there has to be a tensioner,usually gets the back of the belt if its a flat pulley. U may have to remove the spring and then reattach the spring after the belt is routed.

Your drive belt is worn/slipping