OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk Hydro Transmission Overhaul?

Hi
Anybody have any experience overhauling / repairing Hydro-Gear transmissions? Got a Toro zero turn with one hydro not driving forward or reverse....

Dieselboy,

If you have the model of the hydro gearbox we could load the repair manual for it into the parts list and repair manuals area. .

Thanks for that, here's the link....
http://www.hydro-gear.com/main/service/service-repair-manuals
I as hoping someone had experience pulling one apart.....

I think Bruce will need to know the actual model number of your transmission.

The sticker shows
ZK-KCBB-3K5A-2WLX

0147D40287

Well, ZK-KCBB-3K5A-2WLX is a valid transmission code, which leads to an Illustrated Parts List, and the IPL seems to be identifying it as a ZT series transmission:
http://www.jackssmallengines.com/Jacks-Parts-Lookup/Manufacturer/hydro-gear/3571/3223

You can download the ZT service manual (free) here:
http://www.hydro-gear.com/Main/docs/service-repair-manuals/zt-2800-3100-3200-3400.pdf

I suggest you look closely at that manual and see if it covers your transmission.

Aside from that, you said it isn't driving, forward or reverse. Do you mean that wheel will not rotate? The reason I ask is this extract from the ZT manual:

"The ZT-2800, ZT-3100, ZT-3200 and ZT-3400 have an internal cog style parking brake. It is essential to fully disengage the brake prior to operation."

Usually, warnings like that in a service manual suggest that this may be a common source of trouble. If you have a cog style parking brake, and it is not fully disengaged, that wheel isn't going to rotate much.

Thanks for the input.
Already downloaded the relevant Parts Manual ans Service Manual from the link I supplied above. The cog style park brake has been totally removed / disconnected to eliminate it being a factor. My enquiry is if anyone has experience stripping / dismantling/ repairing internals as there is very little on the web......

The process for overhauling the transmission is largely generic. Once you are sure there has not been an error (such as pushing the transit lever for that transmission, or the parking brake engaged, or a low fluid level) you have two basic possibilities: a broken gear in the transmission's drive train after the hydraulic motor, or gross leakage past the pistons of the hydraulic pump, hydraulic motor, or both. A leakage problem is either caused by sustained overheating or fluid contamination, but does not develop suddenly: drive is lost progressively. A broken gear is an all-or-nothing situation: one moment you have normal performance, the next moment you have nothing. Often the transition from all to nothing has coincided with some genius trying to do wheel-stands, or use the machine as a bulldozer.

Thank you!
That's exactly the sort of info I was after!
The mower was towed onto the sidewalk for council pickup last weekend by a neighbour who was quoted $3300 and 12 weeks.....!

If you can get a look at the hydraulic fluid, you'll know whether it has been overheated. Of course it is possible that it was both overheated and mechanically abused, resulting in more than one failure. If the parts are available, a broken gear should not be too difficult or expensive to fix. A worn-out/cooked pump and motor, though, needs a new overhaul kit which supplies replacement pistons/cylinders for both the pump and the hydraulic motor, and this is relatively expensive. It is also fairly difficult to fit.

If the fluid is clean in both transmissions, it would seem likely it is a broken part in the drive train of the one that doesn't work, and with the workshop manual to hand, that should be a fairly easy fix. Alternatively of course it could be that there is just an external control that is in the wrong position, perhaps due to the linkage having fallen off, or as I said before, the transit lever could have been pushed accidentally on the inoperative transmission.