Converting my 73 4spd to hydrostatic

[Larry Chamberlain 16]

I wanna convert my 4 speed to a hydrostatic

My 4 speed has two blown axle seals due got filled with water the plug is froze fast can't break it loose now this year while I was plowing is sounds like gears on gears only reason why I wanted to convert it was when I snow blow it would be easier to control the speed so I found a 417a hydrostatic just wondering if it would fit my 73 wheel horse

[ebinmaine 68,205]

The transmission tunnel and steering tower and all of the controls and belt drive mechanism are different from a manual transmission to a hydro transmission. Your best bet really is to find another tractor and use that, or if you really want to convert your own, get a parts tractor from the correct year range.

 

CAN it be done? Yes.

Is it anywhere near practical or easy? IMHO, no.

 

 

It's far far easier to swap engines than manual to hydro transmissions.

[953 nut 55,734]

As @ebinmaine said your best bet would be to buy another  like the 417 that needs an engine and swap your good engine to it.     The engine pulley on a hydro is larger than the one on a 4 speed so you'll need to get that too.

[pfrederi 17,856]

What horse power is your 73...Hydro for snow plowing you would want at least 12hp in my opinion.  I agree easier to swap your engine to the 417a frame/rearend..

[Ed Kennell 38,598]

49 minutes ago, Larry Chamberlain said:

 when I snow blow it would be easier to control the speed

Yes ,IMO, infinite forward/reverse speed control is not only more convenient, it is a must when blowing snow with a single stage blower where you must keep the blower housing full of snow to keep the chute from clogging.

As stated above, converting a gear drive tractor to a hydro is not a practical solution.   I'm sure you could buy a working hydro tractor for less than this conversion would cost.

16 minutes ago, pfrederi said:

What horse power is your 73...Hydro for snow plowing you would want at least 12hp in my opinion.  I agree easier to swap your engine to the 417a frame/rearend..

                                                                                                                                      The hydro requires 1.6 HP just  to run the pump.

[ebinmaine 68,205]

2 minutes ago, Ed Kennell said:

Yes ,IMO, infinite forward/reverse speed control is not only more convenient, it is a must when blowing snow with a single stage blower where you must keep the blower housing full of snow to keep the chute from clogging.

As stated above, converting a gear drive tractor to a hydro is not a practical solution.   I'm sure you could buy a working hydro tractor for less than this conversion would cost.

                                                                                                                                      The hydro requires 1.6 HP just  to run the pump.

 

I've read and heard that number can be higher depending on temperature and terrain.

I couldn't tell you where but I've seen that numbers as high as two to three horsepower are needed on a regular basis.

[oliver2-44 9,847]

There’s currently a thread my member Cleat who is doing that swap. Lots of great info. 

 

Edited Wednesday at 03:56 PM by oliver2-44

[Handy Don 12,436]

33 minutes ago, ebinmaine said:

 

I've read and heard that number can be higher depending on temperature and terrain.

I couldn't tell you where but I've seen that numbers as high as two to three horsepower are needed on a regular basis.

My readings when I was curious about this wandered into some serious engineering papers. Cutting to the chase, they concluded that geared transmissions were anywhere from 92 to 95% efficient. Hydros ran from about 80 to 83% at horsepowers in the 10-20 HP input range. Higher HP was more efficient for both. I don’t recall anything about operating temperature ranges. 

 

Put into HP terms, a 10 HP tractor would have ~9.5 HP at the wheels geared and 8 HP hydro. The difference being 1.5.

A 14 HP tractor having ~13 geared and ~11.4 hydro. for a 1.6 difference

So, at 20 HP the difference between an efficient gearbox and a not-so-efficient hydro could easily be 2+ horsepower at the wheels.

 

Edited Wednesday at 03:00 PM by Handy Don

[Handy Don 12,436]

As an addendum to the above, where is the extra HP going? To heating the fluid in the hydro. Hence the fins on the pump/motor bodies and the fans.

[Maxwell-8 4,289]

1 hour ago, Handy Don said:

As an addendum to the above, where is the extra HP going? To heating the fluid in the hydro. Hence the fins on the pump/motor bodies and the fans.

And that is why putting a smaller pulley on a hydro wont make it much faster. Just making more heat.

[Handy Don 12,436]

27 minutes ago, Maxwell-8 said:

And that is why putting a smaller pulley on a hydro wont make it much faster. Just making more heat.

Certainly that’s part of it, but the other factor is that trying to push the fluid too fast causes cavitation within the pump (think of frothing the oil) which reduces the efficiency and can damage the pump.