Hydro disengage vs not

[elixir20 1]

My 1979 C-161 Twin Auto has a hydro disengage lever, while my 1995 416-H does not. In is there a reason why in some models the pumps are always engaged and others have the manual engagement?

Thanks for the info...

[Sparky-(Admin) 23,762]

I cant tell you why some have it and others dont, but as your probably already aware your tractors have different hydro's. A Sundstrand in the old tractor and an Eaton in the newer machine. Sundstrands all had a way to disengage while the Eatons don't. I'm sure we all wish there was a way to get the Eatons to free wheel as its gotta suck when an Eaton equipped machine craps out miles from the garage or shed .

Mike.........

[elixir20 1]

Thanks Mike. I'm hoping to not have to worry bout that pushing thing! Now that winter has arrived it seems to make more sense to have a disengagement for the hydro to let the engine warm up before adding the drag of a cold hydro.

[AMC RULES 37,232]

Humm, the Eaton in my '88 520-H has one? :scratchead:

[Sparky-(Admin) 23,762]

Humm, the Eaton in my '88 520-H has one?

I might be wrong Craig but your lever is not a hydro pump disengagement lever or a bypass like the Sundstrands have. I thought that your lever took tension off the belt and was supposed to set a parking pawl (parking Brake).

Mike..........

[can whlvr 994]

i know my 1990 312hydro with 11 series doesnt have it and it should,i left her outside a few nights,its been really cold,she barely turned over,a belt disconnect would be nice,like my sundstrand has

[TT-(Moderator) 1,162]

The (drive belt) disengagement lever was used with all Sundstrands from 1965 to 1980. Up until the addition of the external brake drum in 1978, it also applied the parking brake (pawl) inside the Uni-Drive transaxle case.

Sundstrands also had a bypass (tow) valve, which allowed the fluid to bypass within the pump. In order to push or tow these models, the belt disengagement lever had to be in the "operate" position and the bypass valve had to be opened.

I'm still trying to sort out why all of the "earlier" Eaton-equipped machines (up until 1989?) continued to use the belt disengagement system and why some of the Kohler-powered tractors continued to use it until the end of production while the Onan-powered machines didn't.

The Eaton 7 series does not appear capable of bypassing internally and cannot be pushed or towed. The 11 series has an internal bypass and although they can be pushed or towed, it must be done slowly.

I will say that my 1990 416-H has absolutely no problem turning over when cold and it will usually move immediately. The hydraulic lift does take a while to respond, and when it's ready there is an audible "groan" from the hydro unit and the engine rpm pulls down slightly.

I've had the belt tensioner lever on my GT-1848 locked down since I got it because I can't stand the constant rattling. Even with the el-cheapo B&S starter, it has no problem turning the Eaton pump when cold.

[Hydro 131]

I wonder if it has to do with the drag on the starters. Every kohler powered hydro I have seen has the disengage lever. I can tell it's makes starting a lot easier because I soon as I engage my hydro it really pulls down the rpm. Neither of my two Onans had it '90-520 and 92-416.

[TT-(Moderator) 1,162]

The Onans do have a wound-field / solenoid-shift starter much like used on automobiles/trucks. Kohlers have a permanent magnet starter with the "spin me fast enough and I'll engage" helical drive. There's no doubt in my mind that the Onan starter does produce more torque.

That's been my tentative answer for a while, but I don't have the facts to back it up.

[Hydro 131]

That would make perfect sense then because it's identified as a cold weather device and that would sure affect the rpm of the Kohler trying to get it started. I think it's a great feature regardless just for the ability to disengage the hydro when pushing the tractor around the garage.

[elixir20 1]

TT-My 1995 416-H has no trouble starting in this weather. The manual tractor put the fear of big $$$$ in me by stating severe damage will occur if the hydro is operated when very cold. I have just let it run at a moderate rpm for 5 or so minutes to get things flowing. My lift also makes a groan when operating.

[can whlvr 994]

so if the kohlers had disconnect why not the 1990312-h,because its a small engine to turn over(TOO SMALL)

[Hydro 131]

I don't know about yours...I had a 1990 312 Hydro I bought used and owned it for 5 years. It definately had the disengage system. It was a 1990 because I verified that by Model number. It was great little tractor but I never ran it in the winter. My next tractor was a 92 416H and I was surprised it did not have it. I have since come to learn they didn't seem to be on the Onans...in the later years because AMCRULES has one on his 1988 Onan. That was if I'm not mistaken the first year for the Onan so maybe Wheel Horse had not decided what to do or didn't know for a year or so if it was necessary on the Onan. I'm certainly glad to have this feature.

If you look on the Toro website I think you will find your 312 should have had one.

[Hydro 131]

I just checked the Toro Wesite. They were not on the 312H in 1990. They show them in 91 and 92. I thought my tractor was a 90...now not sure but it definately had one.

[mnWHfan 47]

I think that another reason for the disengage lever was to use the tractor with stationary, pto driven attachments like the 540 farm pto, the wood chipper, and the generator. You could disengage the transmission and engage the parking brake. This would make all of the engine power available to the attachment instead of wasting it on the transmission that's not being used. Just a thought.

[can whlvr 994]

its a mystery,not the first with wheelhorse,i have the model # and mine is for sure a 1990 and no place where the disengage would be,and shes original too,it does move instantly though,maybe my starter is getting weak