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1973 18 Auto (D-180) with a Sundstrand 90-1137 hydro transmission. I have no brakes. The is no external drum, disc, or any sign that there ever was one. Only thing I see is a small lever on the right side, in front of the spin on filter. Moves fore and aft without effect. I've seen later models with a drum and band style brake, but this one doesn't have this. Is there a wet brake internal on this model? Has anyone opened one of these up before? Are reproduction parts even available?

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Parking pall lever, should be moving the parking lever, engage, disengage. The hydro stops it going forwards with the neutral pedal, then I use the forward motion lever by hand when traveling in reverse. I know there are different set ups for D's, including the turning brakes.

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Many hydro transmissions do not use a mechanical braking system.

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If your motion control linkage is properly adjusted the transmission will stop you when the "brake" peddle is applied. Look at the Sundstrand manual on here to see the procedure.

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As mentioned the 18 auto (and some other D's) doesnt have "brakes" at least in the conventional sense. When you press the "brake" pedal all you are doing is moving the hyd lever from fwd/rev to the neutral position. Ive had my 180 for some 30 years and I honestly cant ever remember applying the "brake" pedal, I simply move the fwd/rev lever to the neutral position -- and it will certainly stop you - quickly!

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The lever you mnetion that moved

13 hours ago, a.dumont said:

1973 18 Auto (D-180) with a Sundstrand 90-1137 hydro transmission. I have no brakes. The is no external drum, disc, or any sign that there ever was one. Only thing I see is a small lever on the right side, in front of the spin on filter. Moves fore and aft without effect. I've seen later models with a drum and band style brake, but this one doesn't have this. Is there a wet brake internal on this model? Has anyone opened one of these up before? Are reproduction parts even available?

That lever engages the parking brake If you push the lever up it should engage the internal brake pawl.  In many cases previous users have tried to stop the tractor using the parking brake.  It grinds down the pawl dumping damaging metal shavings into the hydro system and also making the parking brake ineffective.  With brake engages can you roll the tractor???

Edited by pfrederi
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Yes , check the operation and adjustment of that parking brake as it is very important - if it doesn't release it will damage the pawl and possibly destroy the hydro pump/motor system . Also , download the manual for your year and go through all the adjustments for the direction control - the D's have a pretty complicated setup but when it's set correctly they perform quite well . Make sure all the pivot points and rollers that can wear are in good condition , clean and lubricated internally so they work as they should . Mine was so sticky and causing problems from previous owners using chain lube or something similar I had to disassemble the entire thing and rebuild it - works like new now . Make sure to get the correct drawings/instructions for your specific model and year - there are several variations of the D series motion controls that WH used over the lifespan of the D's .

 

The system just acts as a hydraulic brake/stop . When the direction control in the pump is moved to neutral it closes off the oil flow to the hydraulic motor - the internal sealing of the pistons in that motor will stop the weight of the tractor the same as using a friction brake . If it wants to continue to roll - that is a bad sign that the motor and possibly the pump are badly worn or the pump's valves are leaking internally - both requiring a rebuild . There is a place that has some of the Sundstrand parts available ($$$$) so a rebuild is possible with some skills and time . There is a full manual available here for a free download that covers every detail on how to do this - just have to pay attention closely , keep everything super clean and use the manual as well as threads on this forum - it can be done . Look for posts from @daveoman1966 as he has posted some excellent info and pics on the internals of these units if you need to repair it and has some parts as well .

 

Just a note - due to the weight of that tractor - never stop it suddenly if you can avoid it and never ram it full forward/reverse  - you will damage either the differential or the pump system and could also shock load the hydraulics enough to strip the pump coupling between the engine and that hydro pump - that is a part that is no longer available and a proven weak point in this model's design .

 

Sarge

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There was a dampener assembly put on by WH for a couple years to reduce the shock loading from going from forward to reverse to quickly.  If you use your machine heavily may be something to get.

Edited by pfrederi
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Thanks for all the help guys. It took me a while to sort through and find the right manual. I flushed the hydraulic fluid and replaced the the spin on filter (did not see any debris). The parking brake lever does not work. In fact, the lever moves full swing until hitting the oil filter. I suspect the previous owner threw it in park while moving. The tractor can be pushed on level ground without turning the relief valve first... oh boy. Anyway, I may fabricate and add a small disc brake to get by for now. Not ready for a rebuild yet.

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If they did that much damage to the park brake pawl - good chance those pieces are floating around in the bottom of the housing - not a bad idea to get them out of there and it's not too bad a job once you get past getting the hubs off , cleaning the axles up and splitting the case .

 

Sarge

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