# ZTR Mower Hydrostatic Transaxle for Small Buggy



## Tinodesis (May 4, 2008)

Hello,

I have been reading all the electric mower threads like this one;http://www.diyelectriccar.com/forums/showthread.php?t=54833&highlight=turn+mower.

Most of the discussion is focused on powering the blades, not moving the tractor. I want to use this transaxle, https://www.surpluscenter.com/item.asp?item=13-1473&catname=powerTrans to power a ZTR buggy. A buggy I can fit my wheelchair on.

I think I could build a prototype fairly easy by mounting the transaxle on an old 6x6 chassis I have.

Here is a video of a DIY snow plow using the same transaxle. He addeed supports to the output shafts, but that's all and he says it has plenty of power.

http://youtu.be/gaT1r1PC9WQ

Suggestions for voltage and components would be appreciated. What do you think?


----------



## gor (Nov 25, 2009)

Tinodesis said:


> Hello,
> 
> I have been reading all the electric mower threads like this one;http://www.diyelectriccar.com/forums/showthread.php?t=54833&highlight=turn+mower.
> 
> ...


tractor - tool, power tool; focus on blades - power requirements for the job itself (major requirement);
regular push-mower has over 5 hp (4kw) - per blade, at 3600 rpm direct drive (~19000ftpm 20' blade tip speed)

150 -250 watt motor propels scooter to 10-15 mph; minibikes - 500-750w (1 hp) to over 20 mph; small motors propel wheelchair at 5 mph;
5 hp dune-buggy - runs pretty fast... 

so, for 5-10 mph tractor, power take-off for propulsion - not a problem; concern only - the less power - the slower acceleration and lower speed uphill or under load; more chances to stall the engine on sadden load increase;

any type of transmission will do, matter only - cost and headaches

in your case - 2el.motors+2 controllers + 2 one or two-stage speed reduction gears(sprockets) vs. 1 motor + ztr trany(80lbs,$699)
consider prices, efficiencies and weights

i would go with 2 el.motors, though hydro transmission - not bad, but it should fit like a glove - after it chosen, there is no flexibility to change speed, torque -you can play and change mechanical setup - not hydraulic

your tranny - variable speed, constant torque tranny; torque max- 250 f-lbs; continuous - 140;

150 rpm x 250 ft-lbs / 5252 = 7.14 hp - max output (peak, intermittent); 4hp - continuous.


at efficiencies 90-70% it would take 10 hp (7.5 kw) peak, 6hp (5kw) -continuous output power supply (ice or el.motor) for delivering 7hp peak and 4 hp continuous) 

so, chose motor capable of at least 15kw peak (right and left transaxles 2x7.5), 10kw continuous output; volts and amps according to motor specs


smaller motor will do, but would feel underpowered - so be steady, don't push it uphill "full sticks" - when rpm start to go down (under load) - slow down, or relief valve would drop pressure and make you slow down (a lot) : )))


----------



## gor (Nov 25, 2009)

here some calculations - power/torque requirements under diff. grade (slope degree) and acceleration
vehicle weight 500kg (1100lbs) 24''wheels; assuming power 5 kw(6.7hp) - ideal CVT
exact torque at wheels, accel. and speed would depend of particular motor data


----------



## Tinodesis (May 4, 2008)

Thank you, gor! You've given me more help than I expected.

After looking at the numbers, the transaxle will be the limiting factor even with a motor and batteries that are up to the job.

I'm going to think this over some more with the info you provided.

Thanks again.


----------

