New FDR1660 belt tension WAY too tight.

[Pawnee]

I've run this mower for almost an hour and probably shouldn't have. The spindles got pretty warm from the stinkin' hot belt.
I don't know if the tension spring with the chain is the way the factory set it up but this is how I got it.
The spring extends about an inch with 170Lbs hanging on it.

Original setup

New lighter longer spring

Old spring for comparison

That should give the spindle bearings a fighting chance.

 

[Dave_eng]

Please read my comments as trying to be helpful.

If I understand what you have done, you have decided to re-engineer a design from a reputable manufacturer.

Your mower may not have been set up correctly when you bought it..... s..t happens. However, did you adjust the belt tension according to page 27 of the Operator's manual before making the spring change?. see below:

Humans have a hard time assessing a mechanical component's state of stress. I was taught that if, when I touched a metallic part, it felt too hot to touch it was around 130 degrees F. In the years that followed that simple assessment tool stood me in good stead.

What has changed in these 75 years is that the design operating temperature of machinery has gone way up largely with the improvements in lubricants. Now your car or truck engine is normally running well over 200 F.

Designers like these high operating temperatures particularly for machinery which will be used and/or stored in unheated spaces. The high temps drive off the harmful water that will inevitably get into the lubricants from condensation or leaks.

My suggestion is for you to reinstate the mower with the factory parts adjusted according to the manual procedures.

With it adjusted in this way, use an cheap IR temp gun and measure the temperature of the belts, spindles and tension pulley bearing and and record them in your Owner's manual as "Normal" Over the many years you will have this mower, you you have a reference to go back to when parts start to deteriorate.

I find this historical temp record very useful with air conditioning systems. If your new vehicle was discharging 42 F air when it was 80 F outside when it was brand new and now will n o longer come close to that low temperature performance you have a quick way to make that assessment.

Dave

 

[Pawnee]

Yes, I checked the tension per the method in the manual and it was WAY too tight.
The spring that came with was tensioned such that it was extended about 1/16" at most.
The new spring is extended about 1/2" and the tension is just under 10Lbs for roughly 1/4" deflection.
Belts need only be tight enough to prevent slippage. More than that and they put undue stress on spindle bearings.
We've had a Ford 916B for about 35 years now which came that way and the main center spindle lasted less than 15 hours. After I re-engineered the tensioner so it could be adjusted reasonably, the mower has been mostly fine. The outer spindles always had low tension on them and they are still original.
I have an IR thermometer so can check temperature next time I run the mower. I suspect the spindles will still get warm.
Thanks for your comments.