making a PTO gearbox....

Well upon much searching I haven't been able to locate a PTO gearbox (the one that bolts on to the rear of the jeep) at a sane price, so that got me to thinkin'.... What if I made my own?

Correct me if I'm horribly wrong, but I was thinking that....

These gearboxes are literally just a input spline and an output spline, each with a gear mounted on them. So that shouldn't be too hard to make. I've already checked that tractor supply carries gears, splines, and bearings (to have the splines rest on). Now all I'm thinking I would need are some measurements of an original box....

But I would like to know a few things:
- Does the gear box reduce or change the speed at all of the output shaft? Or is it just there as a sort of "convertor" between the pto driveshaft and the yoke that hooks up to the farm implement?

If the input shaft spins at the same speed as the output shaft this should not be a problem at all--just a matter of measuring up an existing box and welding it together.

Speaking of which, anyone have any dimensions of a PTO gearbox?

(Go ahead and let me know if I'm about to embark on a horribly stupid endeavor...)

Thanks,
Evan

 

One more thought....

If I can actually get this to work, I definetly wouldn't mind making a bunch of them everyone on here. I'll just charge for cost of materials, shipping, and say maybe a $10 beer fee. haha. But definetly keep it reasonable so all us jeepers can enjoy a pto on the back of our cj's.

- Evan

 

If you figgure it out, let me know a price

 

I'll bet it gears the output higher than the input. Think about running the bush hog in first gear.

 

The one that I have is geared 1:1, a bush hog is designed to run at 540rpm so even in 1st gear with the bush hog running at 540rpm the engine will be running around 1500-1600rpm.
The one PTO I have consists of an aluminum housing with an input shaft, 2 sprockets, a length of chain and an ouput shaft.

 

Ah forgot about that one, I was describing the one on the transfercase.

 

I've got a spare I'll probably sell once I get it off if you're interested. Needs a complete rebuild. Seals bearings etc. Shoot me a PM if you're interested.

 

Yep! That's the one!

- Evan

 

Do you think that one off the rear is the same 1:1 ratio?

- Evan

 

More than likely as like I said most farm implements are designed to run at 540rpm, it might be geared to speed the engine up but I doubt it.

 

Yeah that makes sense. Thanks!
You wouldn't have any close-up photos or dimensions of one would you?

Thanks again,
Evan

 

Great! Thanks a lot!
- Evan

 

Yeah that definitely helps! Thanks!

Alright... so I've started to gather my parts for one of these...

I've been able to find and input and output shaft along with the 22 teeth gears--all from Tractor Supply in their PTO section. I think NAPA has the bearings and cups I will need to rest the shafts on. I'm also kind of toying with the idea of integrating a slip-clutch into this box (or maybe attached to the rear somehow) to compensate for a bush hog hitting a rock and sending a shock all the way up the driveline and possibly knocking you out of gear... Let me know what y'all think--if it's even do-able.. It doesn't seem too bad, Tractor Supply sells these clutches.

That just leaves that drive flange on the input shaft. I can't find one of those anywhere? Does anyone know if someone sells these things?

Thanks,
Evan

 

I'm thinking of welding together a sort of "box" with a removable, bolt on cover and fill and drain plugs out of 3/16" steel plate. It'll be strong as all hell, only it will look a tad bit different from the original cast case that spicer used.

- Evan

 

Doesn't the power for the part you are talking about making come from a PTO that has a rear output, that is attached to the back of the T Case? Then a driveshaft runs to that gearbox at the rear?

 

The slipper clutch is necessary on a bushhog. It will save your life. The drive train shock is not what you worry about its the bushhog driving you where you don't want to go.

 

Yep, exactly.