AC 712H Lawn Mower Belt keeps breaking

[JB 0]

I have an early AC 712H with 48" lawn mower deck. The
belt for the center PTO that drives the blades keeps
breaking. It seems to be a very awkward arrangement,
with a half twist and using both the V and the flat
sides. Does anyone have advice for making the belt last longer than 2 to 3 hours of use?
(Please email to my son-in-law at sdevi3@cyberus.ca)

[Al 6]

Hi,
If you are having belt trouble, I would check for wear in the pivot arm that has the two idler pulleys on. If the shaft it pivots on has a lot of wear the frame side plate will also. Remove the pivot shaft, and you see apiece of steel with a hole in it that the shaft pivots in. Cut it off and make a new piece, and using a piece of shafting line it up with the hole in the side plate, down and back because the wear is forward and up. Weld it on and get a new pivot arm and it will be like new. We have fixed a number of these. The other thing to be careful of is never run the mower with the deck raised up this goes for 7100s also, as a matter of fact you may see shorter belt life with the mower set at maximum height. Also check the idler pulleys for wear in the bearings. Good luck, AL

[Al 6]

Jeff,
I agree and I just assumed they had OEM belts. We go through this often. As you are aware there is a lot of science in belt applications. There are Simplicity belts that are within an inch of one another and and the price may be 1/2. The cheaper belt can't be substituted for the other application either. This has to do with the cords, cord layers, cord material. the wrap etc. Whether the belt is designed to run backwards around idlers or with twists etc. Ninty % of our belt problems are eliminated with OEM belts. We don't even put aftermarket belts on used uquipment if we have OEM available. I'm not saying there are not other belts that can perform as well, but we see a lot that don't. Also automotive belts and pulleys have a different V angle. Thanks for pointiing this out Al

[Al 6]

And to state the obvious - regular automotive fan belts will also last about what you are getting. If that is what you are using - that is the problem - they are not reinforced inside to take the load that the blades get. You would need to switch to the proper OEM belt IF that is the case.

[tej 1]

First, thanks to Al and Jeff Nemes for their responses. Now I need to determine the part number, length, and cross-section shape for the OEM belt. Unfortunately the manual that Simplicity sent me (the Owner's Manual) does not give these details. Where can I find this information? Again, I have an early AC 712H with a 48" rotary mower deck.
Many thanks (in advance). Ralph Eames, North Gower, Ontario.