Speed variation of deck spindles?!

[Steveo123]

Hi everyone;

I have been working on my 44 inch mower deck, which is under my 1974 IH Cub 108. I have successfully adjusted the mule drive pulleys so that the drive belt actually stays on and doesn't start smoking!

However, I've noticed something strange; as I'm mowing, the spindle on the left side of the deck (i.e. the one whose upper tip is visible while mowing) noticeably slows down, indicating that all three blades significantly slow down. As you might expect, this results in uneven mowing, which in turn means I have to run many more "laps" on the lawn to get all the missed spots.

The tractor's engine (the Kohler 10hp) runs fine, and doesn't seem to be the issue; the spindle noticeable slows down, but the engine speed remains constant. Thinking this was a slipping deck belt, I tightened the tension pulley's spring on the deck by attaching it to the second hole on the deck, resulting in a tighter spring. This doesn't seem to have any effect.

The spindles all seem fine (i.e. they aren't binding up or otherwise indicating any issue(s)).

Has anyone experienced this before? Could it be the drive pulley is not tight enough (i.e. adjusting the j hook to tighten it up? Any thoughts or troubleshooting ideas would be greatly appreciated!

[Red Dave]

Could the PTO clutch be slipping?

Is it in thick, tall or heavy grass, or easy to cut grass?

Are the blades sharp?

Just spitballing here.

[West Valley G]

Just to help with the spit balling the first thing I thought of was. Is the
idler pulley on the deck actually tensioning as it should. Is the spring still
intact. I have had to replace those, have seen them broken.
At least the belt stays on eh,

Ken

[CubDieselFan]

I had a pulley separate on my 102 years ago. Similar symptoms you described. It would spin until it got under a load.

[Steveo123]

Thanks, all, for the input! I apologize for the late reply; I posted, and then had all sorts of things come up. Frankly, forgot that I posted!

I'm going to troubleshoot these things and will repost if/when I figure it out.

Again, thanks!