Transaxle or Wheel motors?

[MikeKle]

I have an old Gravely Promaster 30h outfront,72" deck,30hp yanmar diesel which i am restoring, the engine is already completely rebuilt, the hydro. transmission/pump needs to be rebuilt due to hydraulic pressure loss.Fianally the original transaxle had a cracked case and needs other major work, very hard to find used and new they run $2000!! So I thought about using individual wheel motors set-up instead.It will be similar to a ZTR or WB's set-up.I actually found a cheap source for hydraulic motors($200.new)I realize I will have to fabricate mounts for the motors and modify the tractor a bit.Does this sound practical? This should be a plus because I will be able to increase the width between the drive wheels.Also I thought about making the blades hydraulic driven instead of PTO/belts.This mower will be a beast when I am done with her!Thanks for any help.

[Restrorob]

I realize I will have to fabricate mounts for the motors and modify the tractor a bit.


Being a past Gravely dealer I'd think you have quite a bit of modifying to do to pull this off.

Two wheel motors ran off one pump would mean positive traction on both drive wheels thus rendering the rear steering wheels useless (the wheels would be drug along while turned).

If two pumps were used to feed two wheel motors as a true ZTR and control linkage all fabricated up, The original dash steering controls would need to be removed so Joysticks ? could be installed. Then all original steering components removed from the steering axle assembly and caster forks fabbed up to fit the required size wheel.

IMO, It's a idea but one too labor intense just to mow grass, I'd buy a operational unit and be done with it.....

[GravelyNut]

Being a past Gravely dealer I'd think you have quite a bit of modifying to do to pull this off.

Two wheel motors ran off one pump would mean positive traction on both drive wheels thus rendering the rear steering wheels useless (the wheels would be drug along while turned).

If two pumps were used to feed two wheel motors as a true ZTR and control linkage all fabricated up, The original dash steering controls would need to be removed so Joysticks ? could be installed. Then all original steering components removed from the steering axle assembly and caster forks fabbed up to fit the required size wheel.

IMO, It's a idea but one too labor intense just to mow grass, I'd buy a operational unit and be done with it.....


There have been ZTRs built with one pump and two motors before. But you would need a valve to control the flow to the motors controled by the steering wheel on a 30-H. Independant brakes might also help. It would take some engineering though to get everything setup correctly, but it could be done.

As for buying a used one, likely to be cheaper too.

But remember, Gravely never built a 35 HP 4-wheel G series tractor either. But I know where there is one. ;)

[Restrorob]

you would need a valve to control the flow to the motors controled by the steering wheel on a 30-H.

Although that may work something still needs to be done with the steering axle (casters)......


And I found your "G" quite a nice up-grade.....http://www.xtremesystems.org/forums/images/smilies/thumbsup.gif

[GravelyNut]

Although that may work something still needs to be done with the steering axle (casters)......


And I found your "G" quite a nice up-grade.....http://www.xtremesystems.org/forums/images/smilies/thumbsup.gif
If you had 2 flow control valves hooked up to the steering linkage, steering wheels could be left as is. As one valve opens more, the second would close. That would give you the differential action needed. As the 30-H doesn't need to spin on a dime, just cutting the flow in half to the one side should be more than enough.

Gravely Pro Master 20-G ZTRs use an open differential in the 800/8000/G series 4-wheel tractor's trannys. But if you turn it sharp, you'll still spin a doughnut. Wouldn't be the first time a Gravely left its mark in the grass.
:)
And thanks for the thumbs up.:waving:

[Restrorob]

OK,

Would this stock Gravely pump valved to operate only the steering and deck lift have enough ballz to drive two wheel motors added to the system ?


Still sounds like too many what if's to warrant all the labor time involved.....

[MikeKle]

I have actually decided to start from scratch and build a small tractor,using the Yanmar engine and some of the hydraulic parts,I plan to use the wheel motor /pump set-up,and looks like I will have to buy 2pumps and 2 wheel motors! I could use a small tractor more than a outfront mower that is slow compared to todays mowers!I plan to make a regular 3pt hitch so I can use regular tractor implements,That Yanmar has plenty of life left and this should be a good long term project depending on cost I might even add 4WD!The way I have come to understand is:for every one wheel motor ,you must have one pump? Is that correct? and another pump for the implement circuit? I wonder if there is a way to use a BIG pump that would power multiple motors and PTO's.Or I should I just look for a tractor that has a blown motor and stick my Yanmar in it! Thanks for the input.

[GravelyNut]

OK,

Would this stock Gravely pump valved to operate only the steering and deck lift have enough ballz to drive two wheel motors added to the system ?


Still sounds like too many what if's to warrant all the labor time involved.....
Likely not.


I like pushing the what ifs to the breaking points sometimes. And after seeing some things that Gravelys had attached to them over the years, so did Gravely. Take a Terramite backhoe on a 6.6 HP L as an example.
:usflag: