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Need tips on hydrostatic drive.


rmueske's Avatar
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Join Date: May 2007
Posts: 15

06-04-07, 04:25 PM   #1  
Need tips on hydrostatic drive.

I took on an old Noma Eaglestar 39" riding mower from my next door neighbor. He gave it to me for free. I've been a mechanic for 25 years but never had the chance to dig into a riding mower. This one needed an engine, I found one and made the swap. I put on the belts, and got it running. So far so good. Now here is where I'm kind of lost: This thing doesnt appear to have brakes (?) (!). And when I put it in gear (at idle , of couirse, since it doesnt appear to have brakes) it doesn't move. Any help/advice/operating info would be appreciated!

 
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puey61's Avatar
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06-04-07, 05:16 PM   #2  
When you say "put it in gear", do you mean either step on a pedal or move a hand lever for the transmission control? Or, do you, perhaps, have a shifter tranny where you do put it in gear? If this is a hydro, there likely is a freewheel lever that enables you to move the tractor around without the engine running and you should be sure that this lever is in the engaged postion. You believe that this does not have brakes, but I wonder if the brakes are actually seized thereby locking up the drive train and giving you the impression of a tranny issue. Are you able to freewheel the tractor without the engine running or at all? Another possible problem is if someone ever had one or both of the rear wheel off and unknowingly forgot to reinstall the axle key(s). If only one were missing, you'd have no drive. Post back with the ID numbers off the chassis so we can see exactly what you have for a tractor.

 
rmueske's Avatar
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06-04-07, 05:55 PM   #3  
Thanks for the quick reply! I checked the plate on back, Model # D3912150, code 3070. Eaglestar 12 HP Hydrostatic drive. Right now you can push the mower easily anywhere you want, it rolls with no resistance. I looked for a "freewheel lever" but did not see one, but I haven't looked underneath it, just what you can see without lifting it up. I can turn the input pulley easily when the belt is disengaged. When I said "put it in gear" I meant put the selector in either the forward position or the reverse position, with the engine idling. There is a pedal that controls the belt engagement on the hydrostatic drive, when it's down, the belt is disengaged. This seems like it's the brake pedal, but in looking at the linkage coming off of it, there doesn't appear to be any brake assembly involved. There is a pedal right next to it to lock it in the down position. I released the pedal with the engine idling and heard a slight sound like a power steering pump, but mostly the belt noise. It hadn't run for a while so there is some rust on the pulleys. I engaged the mower deck belt and the mower blades kicked right in. Where would a freewheeling lever likely be located, this sounds like the most likely cause. The guy I got it from said he got it from his brother, who said it was working ok until the old engine just quit. He took the engine apart and found that the countershaft had broken through the block webbing, taking the cam with it. (there was a 12.5 hp Briggs engine in it, which probably wasn't the original as it says 12 HP on the hood) Could the hydrostatic unit be low on fluid, and would that matter? I'm used to automotive automatics that need fluid to connect to the driveline. I take it the hydrostatic operates differently?
Let me know what you think. I really appreciate your help!
Rick

 
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06-04-07, 06:15 PM   #4  
Bear with me a day, I'm not at my shop right now and the only available lookup for this machine is on microfiche. This is an older Noma (Murray) mower which went bankrupt about 2 years ago. They (Murray) were bought out by engine manufacturer Briggs & Stratton but Briggs does not provide much support for the older (Noma) mowers. I'll do a lookup and see what you have and what to look for. Stay tuned. Generally though, there should certainly be a freewheel lever and it may well be underneath the chassis but on the tranny. Also, the brake assembly should be on the tranny exterior and should have a rotor/pad setup with linkage and spring engagement method. Stand on your head and have a closer look for this and the freewheel lever, in the mean time until I can advise you better.

 
rmueske's Avatar
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06-05-07, 06:45 PM   #5  
Thanks Puey!

You hit it on the head with your first reply. I got to thinking about what you said about the axle keys, and decided to check to see if they were there. Sure enough, the right side key was missing. They probably took it out so they could move it after they blew it up. From what I could see there is no freewheeling disengagement lever.
I installed a key, reinstalled the wheel, and ta-da! it works!
It's got a little more noise in forward than reverse, probably due to wear. It seems to operate ok and the noise decreased the more I drove it. I'm thinking it would be a good idea to change the fluid in the hydrostatic unit. I can't see where you are supposed to drain or fill it though, and don't know what type of fluid to use. I've seen other posts that recommend 20/50 synthetic oil, any advice?
Thanks so much!
Rick

 
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06-06-07, 02:24 AM   #6  
Sorry, mueske, most of the lower end hydro trannys have no service points internally, which includes oil. You may find a breather tube with a check valve that you may be able to slowly feed some oil. IF so, only add a couple ounces at a time, run the tranny and listen for improvement. Yes, typically, the synthetic 20W50 will be safe to use.

 
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