My Lawnmower Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
I've spent the better part of an afternoon researching what I believe may be an issue with the Electric PTO clutch but have been unable to find any answers. I've read several good post in this forum so I have decided to try my luck here.

I have a Poulan 25hp 48in mover which starts and runs very well. Overall I'm pleased with the job it is doing for me. Recently it has started giving me problems when mowing. Even in short grass or high cuts, the mover begins to loose power as if I was mowing through tall grass. The longer I mow the worse it gets until I have to slow to speed bested by a push mower.

The mower deck seems fine; I first thought that maybe a bearing was perhaps heating up and beginning to seize, but when not engaged, the blades can be rotated easily.

My next thought is that the something similar is occurring in the PTO clutch. Perhaps their is something heating up causing the brake portion of the clutch to begin engaging causing extra burden on the engine.

One thing I should mention is that at the end of last season, by son was mowing and didn't see long cable laying in yard used for a dog 'zip line'. He ran over the cable which wrapped up in the blades and caused the blades to stop and very quickly stalled the engine. Not sure if this could have damaged the PTO clutch.

I'm hoping I don't have to replace the clutch- and am open to any suggestions or advise anyone may have.

Thanks in advance-

Hal
 

·
Administrator
Joined
·
6,224 Posts
Welcome to the forum Hal!

Couple thoughts..

(1) How's your belt tension?

(2) Wondering if a key may have sheared on one or more of the pulleys from the zip line being wound up on the blades allowing one of the drive pulleys to turn on it's shaft?

Any sounds or smells as the blades seem to slow down? Your engine rpm stays up, correct?
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #3 ·
thanks for replying.

- The Belt tension seems fine and there doesn't appear to be any abnormal wear in the belts that might indicate any slippage.

- I haven't really checked specifically for any sheared keys. With the blades engaged, there is not any missed sections in the grass so I have assumed that all blades were working. I will check again.

- There really isn't smells or sounds as the things slow down- the Engine stays at or near full RPM, but you can tell that it is really working very hard.


Thanks again for your reply and suggestions-

Hal
 

·
Administrator
Joined
·
6,224 Posts
....I haven't really checked specifically for any sheared keys. With the blades engaged, there is not any missed sections in the grass so I have assumed that all blades were working. I will check again.
If one of them is slipping there ought to be some fine metal shavings or metallic dust close by to give it away. Same with a slipping clutch. Another possible test would be to see if any of the bearings seem to be running hotter then the others after you shut it down.

I can't help but suspect it is related to the zipline incident. The blade spindle bearings and the clutch would have taken the brunt of that. I wound up some twin on mine years ago and it heated up and took out the lower grease seal on a blade spindle bearing. Eventually due to lack of grease and dirt getting in the bearing loosened up. Oddly enough it really did not make much noise but it allowed the blade to wobble enough that the grass looked like it was being chewed instead of cut on one side of the deck. It was bad enough at that point I could take hold of the blade and wiggle it enough side to side to hear a clink. :eek:

One other thing a quick stop like that could cause would be a partly sheared flywheel key on the engine. But normally that would show itself with the engine running poorly or not running at all since it throws off the spark timing.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #5 ·
Well I'm back. I got side-tracked on other projects and am back on this. I pulled the deck of the mower and checked each of the spindles. They all spin good and little to no play. Greased 'em up anyways. The belts check out good- no flat spots, cracking or significant signs of wear.

The mower starts and runs great. When I engage the PTO, you can tell that there is a drag on the engine and it shutters a bit then smooths out. As I begin mowing, I can gradually feel the engine being dragged down. The blades still cut great the mower itself loses power.

I think I've about decided that it is the PTO- Are you aware our to check it or if there are adjustments?
 

·
Administrator
Joined
·
6,224 Posts
...Are you aware our to check it or if there are adjustments?
Probably has an air gap adjustment. But you would need to figure out who made the clutch and try to find a service manual for either it or the tractor in general to really know what specs to set it to.

You could try running your Poulan tractor model number through Sears Parts or some other online site to get a part number for the clutch and that might also tell the manufacture of it. From there might be able to get some information from the clutch manufactures website.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #7 ·
Just following up on a mower woes. After I did a quick check of the Blades/spindles and assumed they were good- No Excessive heat variance between them, no metal shavings, no grinding sounds excessive play- I concluded that it must be the PTO clutch. Found one for a somewhat reasonable price and installed it, but unfortunately it did not solve the problem.- Probably not a complete waste of money as one bearing was slipping a bit but could have probably lasted another couple of years.

I have now removed each of the blade spindles to check the bearings. Nothing obvious but what I'm not sure is how freely the bearings should spin. Without the belts on, I could give the blades a spin they would go around several times (5-7) , however without the blades they seem a little tight.- they would not spin freely. Not sure if this is normal. They are seem all about the same. At this point I'm not sure what to do next- perhaps just replace the lower and upper bearing, but hate just replacing parts in trial and error.

Thanks for giving attention to my ramblings :)
Hal-
 

·
Administrator
Joined
·
6,224 Posts
Unfortunately I'm running out of ideas too aside from grasping at straws. :dunno:

With that much drag one would think something should be getting real hot somewhere. Wonder if it still could go back to an engine problem that is causing loss of power under load? Lean fuel mixture or weak spark maybe?

Do you notice any hesitation when quickly moving the throttle from idle to full rpm after the engine is good and hot?
 
1 - 8 of 8 Posts
Top