1811 Hydrostat questions

[ideal_trucks]

I just bought a 1 owner 1811 with 1700 hours on it. Excellent shape for the hours, all maintenance records, etc. Runs great and mows great.
The hydrostat has a couple issues though. First, one check valve is leaking out the little hole in the top. I know that means I need a new one and plan on doing that soon.
The hydro will slow down up a hill and speed up down a hill. Maintains speed fine on the level part of the yard. The only hydro's I've ever driven are the foot operated, so I'm not sure exactly if this is right or not. I've read on here that the trunnion can be worn and cause this also. I've looked at it and the metal doesn't really seem worn that I can see. The big spring is loose, as you can see in the pics.
So, could the spring cause this? The Leaking check valve?
Also if someone could explain to me exactly how the trunnion works that would be great. I've read a lot on the internet trying to figure it out but really just don't get it yet. I'm very technically minded. Probably just don't understand enough in general about hydrostats.

[inspectorudy]

Congrats on a getting a great tractor. On the issue of the up and down traits your tractor exhibits mine does the same thing. First of all you are supposed to operate these things at full throttle and the governor will add or subtract a little from that max rpm. But as with any hydro tranny you will gain or lose speed going up or down a hill. I sometimes add a little power going up and pull a little off going down. In an ideal world the speed would be the same up or down but it is not a necessary requirement. I cannot help you with your other questions but I am sure someone here will.

[J-Mech]

Originally Posted by ideal_trucks

I just bought a 1 owner 1811 with 1700 hours on it. Excellent shape for the hours, all maintenance records, etc. Runs great and mows great.
The hydrostat has a couple issues though. First, one check valve is leaking out the little hole in the top. I know that means I need a new one and plan on doing that soon.
The hydro will slow down up a hill and speed up down a hill. Maintains speed fine on the level part of the yard. The only hydro's I've ever driven are the foot operated, so I'm not sure exactly if this is right or not. I've read on here that the trunnion can be worn and cause this also. I've looked at it and the metal doesn't really seem worn that I can see. The big spring is loose, as you can see in the pics.
So, could the spring cause this? The Leaking check valve?
Also if someone could explain to me exactly how the trunnion works that would be great. I've read a lot on the internet trying to figure it out but really just don't get it yet. I'm very technically minded. Probably just don't understand enough in general about hydrostats.

Yes you are correct about the leaking valve. Replace it. As far as speed regulation, this is normal. Read this, it should help you understand the hydro.

[_DX3_]

The leaking valve isn't caused by the trunion spring issue. It is just old. I would add a couple of washers to the trunion to tighten it up a bit, or, simply order new springs and ends and it should be fine. These cub's do require moderate hand operation for the hydro if your yard is not all level.

[ideal_trucks]

THanks for the info guys.
How hard is it to change the trunion springs? Can I just remove the fenders, compress and they come out? What difference will I notice by replacing. A smoother speed increase and decrease?

[J-Mech]

Originally Posted by ideal_trucks

THanks for the info guys.
How hard is it to change the trunion springs? Can I just remove the fenders, compress and they come out? What difference will I notice by replacing. A smoother speed increase and decrease?

Being that they metal is not wore out around them, you probably wouldn't notice much change. No, you have to take some of the linkage apart, you can't just "compress" them and get them out.

[inspectorudy]

I know it's hard for most of us to leave well enough alone but if your new tractor is doing its job then why not just use it and keep it up on oil and tranny fluids and don't expect it to be a new tractor. I went crazy with mine trying to get it near perfect but now I treat it like a dependable old friend. It has some quirks and some under engineered parts but in its day it was pretty modern. I have owned some more modern tractors and enjoyed them but the old 1811 is still my favorite. Make it dependable but don't try to make it perfect.

[ideal_trucks]

If I do decide to replace the springs maybe this winter when mowing is over and I have nothing better to do, do I need any new clips or anything like that, or does everything come apart easily? Will I have to take the hydro unit out of the tractor, or just pop off some linkages?

[J-Mech]

It can be done in the tractor. It's kinda a PITA, but you can do it... No, unless something else is wore out, or you break it during disassembly, you shouldn't need anything else.