Rotary Cutter Howse question -- splines shot and MF 231 won't lift it

[Rford]

Two issues with my friend's equipment and let me say I'm very inexperienced so feel free to talk very slowly to me:

7 foot Howse brush hog....the gear box shaft splines to the jump stumper, and the stump jumper splines are toast...both are basically worn slick. No idea how that is even possible. Splines should not get torn up especially with a slip clutch system. Other than the obvious replacement of parts, are there any tricks to get this thing working again? I thought perhaps drilling a hole through both and using a soft bolt to connect them might work. But probably just snapped bolts is what I'd end up with.

Second...Is is possible that the MF 231 hydraulics aren't powerful enough to lift the mower...I've read and reread the manual to make sure I'm putting the levers in the proper position, and I've experimented with it, but cannot get the thing to lift it off the ground more than a few couple inches. With the mower off, it seems to lift it higher. Could the mower be too heavy? That said, once, when I was first fooling with it, it did raise it higher up into what I would think was the transport position. Never been able to get it to do that again. I've checked the fluid level. It does come up some, but awfully slowly. This tractor has a front end loader. It seems to work just fine. I don't hear any strange noises.

 

[sweettractors]

I can help with the geaarbox output shaft and the stumpjumper. The 7 ft is pretty heavy and may be about all the tractor wants to lift. You are getting close to the limit? Have you tried to shorten the toplink to get more lift? Ken Sweet

 

[Rford]

Also, does anyone know if the gearbox for a 6 footer and a 7 footer are interchangeable?

Mr. Sweet. I appreciate the reply. I assume you have the parts that would be needed if I was going to go that route, but with my history with this mower so far, and the number of used mowers in this area, I wouldn't spend the money it would take to buy a new shaft and stump jumper.

I'm still wondering if drilling a hole through them and bolting them together would work...seems like that is all a shear bolt is anyway. Can't see the harm in trying.

 

[Rford]

Well, I'm surfing the net and found at least one possible option myself but its not exactly what I'm wanting to do but someone else might find it useful. It appears that you can buy a gear box for around $100 that comes with a collar that can be welded onto the stump jumper to mesh with the output shaft.

 

[Hooked_on_HP]

Since the stump jumper and the shaft are shot, I would tighten the nut and have someone weld the stump jumper to the shaft. They would probably have to use stainless rod since the stumpjumper is cast. Unless your 7' is different than my 5' I dont see how you could drill through the stumpjumper and shaft to put a bolt through it, there just isn't enough room to get a drill in there.
Bill

 

[sweettractors]

Also, does anyone know if the gearbox for a 6 footer and a 7 footer are interchangeable?

Mr. Sweet. I appreciate the reply. I assume you have the parts that would be needed if I was going to go that route, but with my history with this mower so far, and the number of used mowers in this area, I wouldn't spend the money it would take to buy a new shaft and stump jumper.

I'm still wondering if drilling a hole through them and bolting them together would work...seems like that is all a shear bolt is anyway. Can't see the harm in trying.

Call and ask for me Monday, I have a idea that could help your situation. Ken Sweet

 

[Rford]

Thanks Mr. Sweet

I thought about welding, but I'd have to have a portable welder come to the site and once welded, if the gear box goes bad then I'd have to cut it apart with a torch.

On the drilling/bolt idea, I'd take off the gear box and stump jumper and have a professional machine shop do the drilling. It would be too difficult to do on site and I'd want to make sure it was done properly. My concern with that approach is if I'd break the "shear bolt" I'd have to be climbing under the unit to fix it and that's a pain.

I'll give Mr. Sweet a call and see what he has in mind. (Hope doesn't involve a new cutter

 

[Willl]

I'm going to bet a shop will require the shaft to be removed from the gear box and complete dis-assembly of the cross bar. On top of that your going to have their 'fee'.

If you could buy replacement parts, that'd be the best route IMO.

Next best would be a new box and cross bar.

 

[Rford]

OK, here's what I did, thanks to some free and helpful advice from a very sweet individual.

I tipped the mower upright so I could work on it. Odd deal on this Howse rotary cutter. The splines on the gear box were pretty worn but there were no splines on the stump jumper and didn't look like there ever had been any. The shaft did not appear tapered and I can' t figure out how it ever fit tight together to begin with to allow it to spin. I guess the splines fit tight enough but eventually it spun and got too much play.

I took a couple 1/4 inch cobalt bits (ACE Hardware and Sears bits worked, HD did not) and with the stump jumper on the gear box shaft but with the retaining nut and washer removed, I drilled three holes trying to hit both the gear shaft and the SJ, but I ended up mostly in the SJ and in the "groove" of splined shaft. But I had enough bite on a couple of them to feel good about it. Then I put 1/4 inch by 3/4 steel dowel pins in those holes I'd drilled which dowels now act like "keys". It ends up being a lot like a typical crank pulley and crankshaft keyed set up. The dowels end up giving it the friction and contact to prevent slipping. Will it last? I'll check back when it falls apart.

I tried it today and it seemed to work fine. I'm much more careful now to avoid obstacles but that's a good thing.

Also, and I'll see how this works out, it seemed to me that the "stump jumper" aspect of this mower might cause me some trouble because if the SJ moved up on the gear box shaft as designed when it hit an object the dowel pins could drop out on the rise and it would spin free again. To address that issue I cut a piece of plastic pipe and used it as a spacer. The SJ can't jump now, or not much, a problem perhaps, but all this shade tree stuff makes me much more careful mowing and I'm avoiding any trees over and inch or so. And, fortunately, most of the mowing I'll be doing is on trails I've been over already twice this year.

So, this might work for someone. Cost $15 for 3 bits and $2 for the dowels.

 

[Soundguy]

stump jumpers don't 'jump' they merely allow the mower to ride up over the obstacle instead of stalling on it. IE.. the jumper does not move on the shaft.. though sounds like yours was loose and that caused a problem..

soundguy