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post #1 of 9 Old 08-12-2019, 10:03 AM Thread Starter
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Belt wear on 40" two blade commercial mower

Have a 40" square type commercial mower that I replaced the bearings in the drive head and painted it up to keep it from rusting. Drive is tight and has minimal drag and the two spindles, while not new, have low drag and spin freely. Added two new blades so it has cross blades like a 30".

Problem is it eats belts. Have new tension pulleys and new springs. Tension arms are not slack. Freshly greased spindles. Used 38" belts the first time and after they burned up used 37" belts which do fit but are tough to install (but keep tension longer). Using on a C8 in low axle gear high range in transmission and while it does load the motor when first engaging the drive, it mows and cuts well and the 7.6 hp handles it fine (pretty amusing since most 42" riders are at least 12-16 hp).

Any suggestions? Like the deck, and use it instead of the Craftsmen 42" 19.5 hp rider as it seems to give a better cut.
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post #2 of 9 Old 08-12-2019, 10:10 AM
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Quote:
Originally Posted by nhgravely View Post
Have a 40" square type commercial mower that I replaced the bearings in the drive head and painted it up to keep it from rusting. Drive is tight and has minimal drag and the two spindles, while not new, have low drag and spin freely. Added two new blades so it has cross blades like a 30".

Problem is it eats belts. Have new tension pulleys and new springs. Tension arms are not slack. Freshly greased spindles. Used 38" belts the first time and after they burned up used 37" belts which do fit but are tough to install (but keep tension longer). Using on a C8 in low axle gear high range in transmission and while it does load the motor when first engaging the drive, it mows and cuts well and the 7.6 hp handles it fine (pretty amusing since most 42" riders are at least 12-16 hp).

Any suggestions? Like the deck, and use it instead of the Craftsmen 42" 19.5 hp rider as it seems to give a better cut.
Have you used a long straight edge to make sure all your pulleys are level? Also on the same plane? Does the mower rotate easily with the blet installed? Sometimes a bearing can feel fine but tighten with any die load, (belt tension).

I too am amazed at the torque of these machines. Hope you get it sorted out.
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post #3 of 9 Old 08-12-2019, 06:04 PM
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Re: Belt wear on 40" two blade commercial mower

I would carefully inspect the v-groove area of all pulleys. It's very easy for them to get a little rust in there, and that makes them rough and hard on the belts. Even new mowers have this problem when some owners hose there decks down after mowing, and the pulleys sit till the next mowing and get rust on them.
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post #4 of 9 Old 08-12-2019, 07:15 PM
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Re: Belt wear on 40" two blade commercial mower

Put a straight edge across the pulleys. Just a thought.

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post #5 of 9 Old 08-12-2019, 07:50 PM
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Re: Belt wear on 40" two blade commercial mower

Using kevlar belts ?...Automotive belts wont hold up,anything using an idler pulley clutch needs a kevlar belt to last,and auto belts are different width and taper by enough to make them wear out and fail pretty rapidly.
Also a 37" belt doesn't have that much surface area,usually mower deck belts are twice as long--longer belt = more surface to take up load and heat..


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post #6 of 9 Old 08-13-2019, 09:30 AM Thread Starter
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Re: Belt wear on 40" two blade commercial mower

All belts have been Kevlar.
Pulleys on the spindles are very polished and have no rust. They do run warm! And I am running the mower w/o the top covers. Gear case pulley shows a little corrosion but it appears that the slippage is happening on the spindle pulley. Left side (from operator view) more than the right. Using one of the blades you can rotate the entire system with little effort with the PTO disengaged. No grease leaking from gear drive onto the belts.

Design of the mower only allows the use of 37-38" belts, one per spindle. Each belt only sees load from one blade set. Does not use a long routed in a circle belt like a sit down mower.

My only guess is that the spindles are dragging just enough to load the belts too much. But I can't understand why it mows so well, even in longer grass on the lawn.
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post #7 of 9 Old 08-14-2019, 01:54 PM
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Re: Belt wear on 40" two blade commercial mower

Quote:
Originally Posted by nhgravely View Post
Have a 40" square type commercial mower that I replaced the bearings in the drive head and painted it up to keep it from rusting. Drive is tight and has minimal drag and the two spindles, while not new, have low drag and spin freely. Added two new blades so it has cross blades like a 30".

Problem is it eats belts. Have new tension pulleys and new springs. Tension arms are not slack. Freshly greased spindles. Used 38" belts the first time and after they burned up used 37" belts which do fit but are tough to install (but keep tension longer). Using on a C8 in low axle gear high range in transmission and while it does load the motor when first engaging the drive, it mows and cuts well and the 7.6 hp handles it fine (pretty amusing since most 42" riders are at least 12-16 hp).

Any suggestions? Like the deck, and use it instead of the Craftsmen 42" 19.5 hp rider as it seems to give a better cut.
I think I would try it with a single blade on each side like it was designed, and see if that makes a difference. You would think that would take some load off the belts.
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post #8 of 9 Old 08-14-2019, 02:36 PM
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Re: Belt wear on 40" two blade commercial mower

How low do you cut you'r grass... How thick and high is it... How fast do you go?


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post #9 of 9 Old Today, 05:27 AM
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Re: Belt wear on 40" two blade commercial mower

I just recently serviced one of these units. Agree to run the single blades as designed but also check the idler pivots for wear. This was my issue when breaking belts. So idler pulley was not running level. Replaced idler pivot and also switched to clogged NAPA belts and all has been fine.

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