Hydrostat question

[Roger66]

I think that's it, The little Deere must have a relief valve to keep it idiot proof combined with more engine power than hydro power makes it feel more powerful than it actually is. My Big tractor just has a little 25 HP engine and no relief valve so it feels less powerful than it actually is as you can easily stall the engine under heavy load. The weight this little JD tractor has pulled and for the last 20 years is amazing! that trans-axle is bullet proof. Particularly the tong weight it's endured. I've never even changed the hydro fluid! I'm not sure if I've ever even checked it, putting that on my to do list now. It's on lighter duty now that I have the bigger tractor. Now it's primarily used for gutting grass like it's designed to do. I didn't even buy a cutter deck for the red tractor.

 

[DieselBound]

I think that this JD mower is not representative of today's lawn tractors. There's a long thread around here about folks complaining about failed HSTs. Seems that towing excessive loads is a big killer. If there was proper relief happening I'd think that that would tend to make things more obvious, likely save a lot more transmissions in these things. NOTE: the discussion noted that manufacturers mentioned to not tow excessive weight, but there's little to indicate how much that is (what the actual towing capacity is): problem is is that operator weigh needs to be factored in (and, well, it's really a riding "mower," not really a towing machine, though they put a "receiver" on these things!), and what sort of inclines one might tow up/on; but, this all could be tested and noted/quantified as the more practical CGVW (which is the means by which all on-road hauling is assessed). Blame today's manufacturing processes of "integration," of using outside bits that one has little control over (consider the long-running squabble Ford and Navistar had over the 6.0L).

 

[ruffdog]

Maybe mowing machines are more apt to have a hydro pressure relief than a tractor to give the mowing deck HP priority over pulling. This would keep the blades running a more consistent speed.

 

[Spanner]

Forget PTO, I'm just talking about purely towing load. There is definitely some type of governor on this lawn tractor. I pull a super heavy firewood trailer up a steep driveway. When I run on level ground full pedal it zips along pretty quick, but climbing the hill of course it slows way down, I'm still at full hydro pedal. You hear the engine loading down, but it stays at full revs give or take. If I do the same with the Mahindra the engine revs start dropping and will stall if you don't back off the pedal. The Deere has just one speed range and the Mahindra has 3 ranges and behaves the same in all three ranges just more dramatic in high range of course. Even in Low the Mahindra can't pull that same heavy trailer up that same hill at full pedal without stalling or nearly stalling. The little 19 HP gas Deere can. This is not to say the Deere is better at all, it's just easier to drive. The Deere automatically slows down downshifting if you will as the load increases. On the Mahindra I simply need to reduce pedal slow down a bit and then it can easily out tow the little Deere. You just need to drive it different as People on this forum pointed out to me. Not really a problem at all, but that feature on the little Deere is nice and I was wondering if this could have been one of the advantages of buying a Green or Orange tractor? Me and the Mahindra are getting along fine now that I've learned how to drive it.

What you are describing here on the JD is the "Governor" on the engine maintaining engine speed under load.

 

[Roger66]

It's disappointing that JD HST's quality has gone down! This one has thrived on nothing but neglect and abuse. I've frequently towed excessive loads with mine! To the point that I had to add a big lead front bumper to just to try and get some steering. My firewood trailer is beyond excessive for this little thing and it just keeps going.
That's the thing that makes it so hard to make an intelligent buying choice, just because they were good 20 years ago doesn't mean a thing about today's quality! Then take a tractor like my Mahindra 1526. It's made by Mitsubishi in Japan, but the 1533 is made in India if I'm not mistaken and there are other models made in Korea. Some may be good others might be bad, but you can't say the brand is good or bad as a whole. Mahindra is probably an extreme example, but in this world economy these days The tractor may be made in country X, but the engine came from country Y and it all fell apart because of a bad snap ring from country Z.