Flail Mower Let's talk flail mowers

[dadohead]

Retired tractor engineer here... I've designed countless belt drives. Maybe I can help.

A twin A-belt drive seems marginal for this application. It is slipping, getting hot, and delaminating. Scary stuff... slipping makes heat and heat can make fire on a mower. A belt drive needs 3 things (minimum) to successfully carry high loads:

• Good belt wrap around the driver/driven sheaves
• Proper tension
• Enough belt to engage the sheave side walls/cord width

First, don't use 4L belts on your mower. These are fractional hp belts designed for low cost, general use applications. Use an 'A' section belt (same dimension but much more capable). Your belts are stretching and losing tension probably because the cord is polyester construction. Spec an A belt with an aramid cord; this is another name for Kevlar. They won't stretch. Most general use belts are 'wrap molded' construction.

Wrapped molded belts have some advantages (smooth engagement) but mainly they are cheaper to make. The core belt is smaller so they can cut more belts off of a band. Raw edge belts also have advantages: the cord (that carries the load) is wider and the raw edges really bite into the sheave.

So, find an A belt with aramid cord preferably with raw edge construction. Doesn't matter where it's made. If your sheaves are wide/deep enough for bigger belts (5/8" wide at the widest min)... spec B belts! Hope this helps!

 

[LouNY]

I am surprised that they spec'ed a "A" series belt to me that seems like kind of a light duty belt for that application.
The SP series can be a bit stronger.

 

[scootr]

My Bestco mower has 3 belts.

 

[dieselscout80]

I’m surprised they have belts burning up / breaking.

On my flail mower I have had on belt break since 2010 (2 different Ford 917 & Alamo SHD96).

 

[arto98607]

Sounds like this model mowers do not have belt idler, like for example the old ford 917L Special does?

It does add to cost of building a mower, but it sure helps to maintain belt tension.

Too bad Ford got out of the tractor business, but I think most of us can figure out the reasons why...

 

[dadohead]

Sounds like this model mowers do not have belt idler, like for example the old ford 917L Special does?

It does add to cost of building a mower, but it sure helps to maintain belt tension.

Too bad Ford got out of the tractor business, but I think most of us can figure out the reasons why...

View attachment 1592694

Yes! An idler increases the belt wrap both driver and driven sheaves see. In addition, a 'sprung' idler maintains the minimum tension required for hookup regardless of load so is easier on bearings than a fixed/adjustable idler.

The drive above (with large diameter sheaves, sprung idler, etc) is textbook for long life.

 

[dieselscout80]

Sounds like this model mowers do not have belt idler, like for example the old ford 917L Special does?

It does add to cost of building a mower, but it sure helps to maintain belt tension.

Too bad Ford got out of the tractor business, but I think most of us can figure out the reasons why...

View attachment 1592694

I wish my Ford 917’s idler pulley was spring controlled like yours is!

 

[threeoranges]

I have the same mower and yes the belts took 3 mowing sessions to burn and break.

What happened after that? Did it eventually get normal?

I tried increasing the tension of the belts, but the gearbox had a loud striking noise and I reduced the tension just enough to remove the striking noise. The belts still felt too loose. I couldn't increase the tension anymore without creating the striking noise.

 

[threeoranges]

Maybe a shorter belt would help??

I planned to try A37, but @dadohead and @LouNY have important comments.

 

[DavesTractor]

Is it clear to anyone what the striking noise is?