Replacing jackshaft that's too long?

[Richard]

Arghhhhhhhhhhhhhhhhhhhh

We spun the jackshaft on the Rhino TW-120, 10' rotary cutter. The 1/2 shaft that goes from the main gearbox to the side gearbox.

Ordered new one from factory and went out to put it on today...

The piece measures (round numbers for conversation) 13" long edge to edge. The INSIDE measurement from tip of main gear spline to outer gear spline is 12".

Houston, we have a problem

I'm dumfounded. The OTHER side is also 13", so how do they get these things on there?

I don't know if I will be able to explain it and I don't (yet) have pictures but the shaft has an opening on the spline end obviously. It also has an opening on the other end that connects to those rubber disk doughnut "shock absorbers"

I put the rubber disk end "over" the splined shaft on that side (the shaft will not go INTO the open end but it will allow me to use up much of the 1" length. Upshot... when I do that, I still have about 1/8th inch TOO much length and I can't get the spline end to line up with the shaft.

If I do not put the rubber disk end "over" that spline and simply try to put the spline on the shaft, it's wayyyyyyyyyyyyyyyyyyyyyyyyyy too long and it's also at a bad angle. These are meant to go on pretty straight and that will NOT allow it to be straight so I must do the other way wehre the opposite side is trying to slide over the other shaft.

Sooooooooo, anyone ever have this happen to them and know of a trick?

I DID tap gently yet sharp on both spline shaft almost praying that there'd be a touch of slop in them to push them inward just a fraction of an inch. Of course that didn't happen.

I'm completely dumbfounded...

As best I can tell, the only way to garner the extra fraction of an inch would be to either loosen the entire side gearbox or open said gearbox and somehow loosen a gear inside and then reinstall it after the shaft is on the spline.

I refuse to belive they intended for it to be this difficult.

yeesh...

 

[Farmerford]

If you lift the mower up with the tph (or just hold it up on the tongue if pull type) and put a few hundred pounds weight on the outer edge of the deck (say a couple of guys stand on it) will the deck warp down enough to give you the 1/8" you need?

I assume the jack shaft is the sliding type. Can you cut a bit off the inner and outer sleeves so it will be shorter when collapsed? Might be easier just to loosen a gearbox.

 

[Richard]

Might be easier just to loosen a gearbox.

After thinking on it overnight, I'm thinking you're right. This machine hit something HARD before we got it and that's what buggered up most of the driveline. I'm not sure but I THINK my brother in law said he also replaced several (all??) of the bolts holding the gearbox on that happens to also be the one that got whacked.

It dawned on me last night that when he tightened it down there might be some slop in the bolts that allowed it to skew right instead of left.

I think I've decided I'm going to loosen said bolts, attach a chain around the gearbox with the chain anchored to my backhoe loader bucket (industrial sized) and use a ratchet tie down to try to squeeze the fraction I need.

As for trying to bend the deck, I did try it with the deck on the ground and then with the deck lifted into the air (no luck)

Playing with mechancal things is sure a different game when the parts weigh a couple hundred pounds (the gearbox also has the stump jumper pan and blades attached to its bottom side)

 

[LoneCowboy]

I'm sure you have to loosen/ remove one of the side gearboxes.
If i was designing it, that's what I would do, no possible way for it to slip out.

 

[Richard]

I'm sure you have to loosen/ remove one of the side gearboxes.
If i was designing it, that's what I would do, no possible way for it to slip out.

Interesting logic on no way to slip out!

I guess I'd never made it as an engineer lol

I called Rhino's tech dept today and after he got zeroed in on the specific model we have (they've updated the 1/2 shafts since then) he finally agreed that the best/only way to do it was indeed, to loosen the gearbox & tilt it.

I guess I know what I'll be doing tonight.

What really bites about the design on doing the gearbox thing is the difficulty in getting to the bolts to loosen/tighten them. I only have deep well 6 pt sockets and by the time I put them on the head, there's no room left for my impact or even my socket wrench.

I'm going to buy some regular height 6 pointers today so I'll have something that will work.

His idea was to put some 4x4's or 6x6's UNDER the blade pan, loosen the bolts, LOWER the deck and use that method to raise the gearbox. He said he'd NOT remove the bolts, just loosen them up to get some leeway.

I was thinking on using my method above with chain/ratchet/bucket. Any thoughts on which method??