Rotary Cutter Possible Gear Box Issue

RickinVA · Oct 1, 2013

Hello from the Shenandoah Valley in Virginia.

I'm a new member, and run a 1952 Ford 8N on our 8 acre horse property. My problem is with my Howse rotary mower. It cut fine last month, but when I tried it yesterday the shaft didn't fully engage the blades. If I turn the shaft by hand is turns the blades a little, but slips. and I can turn the shaft the other directions without the blades stopping. If I had to guess I would say it feels like something in the gear box is stripped or slipping. I've never worked on a rotary mower before other than to remove the blades for sharpening. There appears to be plenty of lube in gear box. Any help getting started on this would be greatly appreciated.

Thanks, Rick.

SPYDERLK · Oct 1, 2013

WELCOME ...
On the shaft going into the gearbox there is a coupling holding a shear bolt. The bolt pins the two together and limits catastrophic forces by getting cut in two at the shear point. Sounds like yours is sheared. Look for a couple empty holes on the coupling. Youl have to line them up w the hole in the shaft and tap the piece out of the shaft. Then replace with no greater than a grade 5 bolt.
larry

aczlan · Oct 1, 2013

Look on your PTO shaft where it connects to the gearbox for a bolt hole that goes through the connection, it sounds like you have a shear pin (so that if you hit something too big the pin breaks instead of the gearbox) and the pin is broken.

Aaron Z

RickinVA · Oct 1, 2013

Thanks, guys. That makes sense. I'll take a look when I get home. Appreciate the quick responses.

RickinVA · Oct 2, 2013

Was not the shear bolt. Called Howse and they were very helpful. Ended up being the stump jumper bolt was loose allowing the spline from the gear box to rotate freely in the stump jumper as it had worn down the female end in the stump jumper. May need a new stump jumper if I can't tighten the bolt enough. Sorry for the non-technical description, but I'm not very experienced. Thanks again for the advice. Hope this helps others in the future.

SPYDERLK · Oct 2, 2013

Oh darn .
..I hope the male side, the gearbox output stub going into the sj, is not too worn. Bad to allow them to run loose. Good luck.
larry

RickinVA · Oct 2, 2013

Thanks, Larry.

I think it's ok. That was my fear, too. Unfortunately most of what I know about tractors, etc. has come the hard way as in I didn't know to check that bolt and thought the sj should wobble by design. Oh well, now I know. What's next?