Should stump jumper be loose?

[genusCastor]

I just noticed the stump jumper on the brush hog is loose. I can move it up and down a little on the spindle. The Castle nut was still secured with a cotter pin, so this may have been the way I got the brush hog originally (got it used). I removed the nut to check if the spindle bolt shows signs of wear from the thing being loose, it does not.
[edit to add]: Actually, until I drop the jumper down I won't see where any wear would be. Going to take it off the spindle later today.



TIA

- djb

 

[Gunny]

I don't know for sure, but on both of my rotary cutters, the stump jumper is secured pretty tightly. One is only about two years old, the other is many, many years old. I would think that if I was able to move around or up and down, it'd rub the threads off the shaft

 

[Gary Fowler]

The stump jumper should not move at all. If it moves, it means the castle nut is loose. Perhaps someone removed it long ago and didn't properly reseat it onto the tapered spindle. I would first try to tighten the castle nut to see if it will snug the stump jumper down, if not, then nothing left to do by try to remove it and inspect for damage.

I had to repair my B-I-L's 4 footer once when the stump jumper appeared loose but was actually a broken weld on the spindle hub. The stump jumper is bolted to the spindle hub where a T section of thick flat bar is welded to the actual spindle hub. His was completely broken loose from the hub and only held on by the stump jumper.

So if your castle nut is tight, you need to remove the nut, remove the stump jumper and inspect for damage. Keep us posted on what you find.

PS> I find it easier to work on a bush hog when it is lifted up on it side and held by the FEL (assuming you have an FEL) otherwise an overhead crane works also or even a large tree limb with a chain hoist. It may take some beating an prying to get the hub off. Best action is to pry it evenly from each side.

 

[genusCastor]

The stump jumper should not move at all. If it moves, it means the castle nut is loose...

So if your castle nut is tight, you need to remove the nut, remove the stump jumper and inspect for damage. Keep us posted on what you find.

PS> I find it easier to work on a bush hog when it is lifted up on it side and held by the FEL (assuming you have an FEL) otherwise an overhead crane works also or even a large tree limb with a chain hoist. It may take some beating an prying to get the hub off. Best action is to pry it evenly from each side.

I got the stump jumper off, and the spindle looks fine, no damage. I reassembled and tightened the castle nut down, and it will, in fact, secure the stump jumper. But the nut goes up above the cotter pin hole, so what I think happened is that the castle nut backed down to the cotter pin. Why they would put a cotter pin in below the castle nut...? Maybe they just didn't tightnen it down all the way to begin with.

I'll need to add a shim to get the castle tight tightened at a location where the cotter pin actually secures the nut. There are a couple shims on it already, I have a piece of 5/16" plate, might try cutting a washer out of that. Get to play with...er...ah...I mean use the plasma cutter.

I have the bush hog up on blocks, can get to the blade assembly easy. Might try the tilt method next time tho...

- djb

 

[Jerry/MT]

I just noticed the stump jumper on the brush hog is loose. I can move it up and down a little on the spindle. The Castle nut was still secured with a cotter pin, so this may have been the way I got the brush hog originally (got it used). I removed the nut to check if the spindle bolt shows signs of wear from the thing being loose, it does not.
[edit to add]: Actually, until I drop the jumper down I won't see where any wear would be. Going to take it off the spindle later today.

View attachment 515605

TIA

- djb

The stump jumper should be tight on the gear box output shaft.

 

[pmsmechanic]

Maybe I'm to late but I would coat the whole spline area with never seize before you tighten everything up. It will be a lot easier to get apart the next time.

 

[sandman2234]

If you have a trailer that you haul the tractor on, it makes it a little easier to load the tractor and let the bush hog hang off the end of the trailer, with the front end sitting on the edge of the trailer. Make sure the tractor is securely blocked in place, brakes on, and maybe a chain, just in case. Really depends on the height of your trailer.
David from jax

 

[brown40]

I have an old apple tree I'll lean the cutter against and bind to when I'm working "under the deck", because its too dangerous to actually spend time under a deck. Torquing nuts and bolts on blade, gearbox, and especially the castle nut puts me at the end of a sturdy lever--I can't move the world, but give me a good lever and I can move... a lot. Enough to slide a ton of cutter off blocks, a stand, or anything its not locked in or bound to.
The only freely moving parts should be the blades--definitely do not want sideways leverage exerted against the spindle--will eventually grenade the output bearing if it doesn't put the shaft out of line.

 

[bigtiller]

I have an old apple tree I'll lean the cutter against and bind to when I'm working "under the deck", because its too dangerous to actually spend time under a deck. Torquing nuts and bolts on blade, gearbox, and especially the castle nut puts me at the end of a sturdy lever--I can't move the world, but give me a good lever and I can move... a lot. Enough to slide a ton of cutter off blocks, a stand, or anything its not locked in or bound to.
The only freely moving parts should be the blades--definitely do not want sideways leverage exerted against the spindle--will eventually grenade the output bearing if it doesn't put the shaft out of line.

Sure you can, all you need is a fulcrum, staff and a place to stand.

 

[OzTinkerer]

Hi Guys,
Wotza stump jumper??
Ian

 

[genusCastor]

Maybe I'm to late but I would coat the whole spline area with never seize before you tighten everything up. It will be a lot easier to get apart the next time.

Yessir, done did. I put neversieze on errythang!

- djb

 

[stuckmotor]

Hi Guys,
Wotza stump jumper??
Ian

Ian,
If you look at the rust pitted, saucer shaped object in post #1 of this thread, you'll see a stump jumper. As the name implys, they hopefully allow a rotary cutter to ride over stumps rather than break something that you don't want broken.

 

[OzTinkerer]

Hi Stuck (or should I call you Mr Motor?),
Thanks for that. Sounds good in theory, but I'd think the blades passing in front of the 'saucer' would hit the 'stump' hard and often before the stump jumper gets there to ride over it... Still it's got to be better than a solid bar slamming into the 'stump'. I've not seen one of these on our local 'brush hogs' (we just call 'em 'slashers'). Something to keep in mind.
Ian

 

[stuckmotor]

Ian,
I honestly don't know how much good the stump jumpers do. My main slasher doesn't have one. I have a very light duity slasher which I bought to cut the grass that has a stump jumper but I'd be afraid to take it around stumps.
Stuck

 

[genusCastor]

...the rust pitted, saucer shaped object in post #1 of this thread...

:laughing:

That rust pitted saucer is a mechanism to allow the blades to be mounted so they can swing back and absorb the force if they hit something stationary, like a stump. Unlike a centrally mounted blade that has no way of absorbing the force. The name, stump jumper, may be misleading. It doesn't jump over anything.

Having said that, I wasn't sure if these things were mounted loose to allow even more movement of the blades in the event something is hit.

- djb

 

[jimmysisson]

The bevel on the edge of the disc helps it ride up over a stump. Jumping is a whole 'nother concept.
Jim

 

[Btown]

I got the stump jumper off, and the spindle looks fine, no damage. I reassembled and tightened the castle nut down, and it will, in fact, secure the stump jumper. But the nut goes up above the cotter pin hole, so what I think happened is that the castle nut backed down to the cotter pin. Why they would put a cotter pin in below the castle nut...? Maybe they just didn't tightnen it down all the way to begin with.

I'll need to add a shim to get the castle tight tightened at a location where the cotter pin actually secures the nut. There are a couple shims on it already, I have a piece of 5/16" plate, might try cutting a washer out of that. Get to play with...er...ah...I mean use the plasma cutter.

I have the bush hog up on blocks, can get to the blade assembly easy. Might try the tilt method next time tho...

- djb

My guess is it had a washer, at some point the washer was not put on, either at the factory or previous owner.

 

[RandyT]

Like somebody said the jumper designed to ride up over objects. the swinging blades will bounce back if they hit something, but the solid bar they are attached to won't and a direct impact with a hard object can bend the gearbox shaft, or in some cases can create enough force to rip the bolts from the cutter, or destroy the gearbox itself.