Bigger HST machines.

[oldnslo]

LD1,
I suspect that part of the limitation on higher HP HST transmissions is the potential for losing ground speed in ranges and or requiring more gear ranges to obtain ground speed. Hydraulic motors have limit on what speed they can run so smaller displacements provide greater operating range. I am not sure what displacement motor your current tractor has but as an example a 28 cc motor can operate up to 6,000 RPM while a 56 cc can only operate up to 5,000 RPM. The design engineers also have to consider gear tip speed to ensure the gears keep lubricated, bearing loads speeds, charge pump flow, etc.

No question the there are HST units capable of powering 100 HP tractors but there is a whole bunch of other factors behind the scenes that also have to be considered.

 

[blackvette]

In my opinion, its the long term viability…..all HST machines will eventually fail, and geared tractors will in all likelihood still have a good transmission, when they are rusted out and blown up……hst machines are rarely used when it is absolutely a necessity that that tractor function, in all conditions…..
With big wheel loaders, the trade off is worth it, but thats for a purpose built loader, not a utility tractor .

 

[auxhyd]

Cost, plain and simple. It is already done on wheel loaders some of the newer models have fancy hybrid geared hydraulic drives but they're more expensive machines and they benefit greatly from the quick forward / reverse and the hydraulic braking since they often do it all day long.

Tractors on the other hand are less specialized, intended to work well (but not necessarily great...) for a wide variety of uses, especially in the smaller sizes.

 

[4570Man]

Are you mowing with the loader on or off? Also what about a suspension seat upgrade if you don’t have one already?

 

[LD1]

Are you mowing with the loader on or off? Also what about a suspension seat upgrade if you don’t have one already?

Loader is always off when mowing. No I havent upgraded the seat yet. But if it's too rough for me to keep but in seat it's too rough/hard on tractor. Don't wanna snap an axle or bust a spindle.

I would like to upgrade the seat....I already put a nice grammar on my ZTR. Just waiting on my contact that works on forklifts to hook me up again.

 

[allenr]

Not sure I agree that there is no demand.

20+ years ago the only HST were B-sized and 2000 series Deere sized machines.

Then they upped it to include L and 3000 sized machines.

Then it went to Mx/4000 sized machines.

Just wondering when the next step is. HST is proven technology now....it certainly can't be a physical limitation. Heck....10000 pound 100hp skid loaders are HST.


The "need" for HST is for infinite speed and darn dear instant direction change without levers or buttons. No gears to shift to find the right speed. Not even sure why that is in the realm of discussion as to "why". There is nothing that can hold a candle to HST for what I do. There is no other option where I can go 8mph in thin areas...and slow down to 1-2 mph if I need to without changing gears or flipping levers. Just simply lift off the go pedal. It's as natural as driving a car with an accelerator pedal.

I too would like a larger HST. We have an IH 74 Hydro on our 1970's Chisholm Ryder grape harvester. The transmission still works beautifully and would not consider anything else for this application. However, despite having an engine rebuild some years ago the engine still burns oil, leaks oil and is smoky.
Something about 70-80hp with 540E would be ideal.
I suspect in time CVT might come down to this level and have less power loss but I'm not sure I want the complexity, electronics and probable cab when an old school HST can be so reliable.

 

[pmsmechanic]

I too would like a larger HST. We have an IH 74 Hydro on our 1970's Chisholm Ryder grape harvester. The transmission still works beautifully and would not consider anything else for this application. However, despite having an engine rebuild some years ago the engine still burns oil, leaks oil and is smoky.
Something about 70-80hp with 540E would be ideal.
I suspect in time CVT might come down to this level and have less power loss but I'm not sure I want the complexity, electronics and probable cab when an old school HST can be so reliable.

Have you considered and engine swap? Yes it would be a lot of work but I'm thinking a little cummins in there would be sweet.

 

[pmsmechanic]

I could go an inch bigger at the very max. So not really worthwhile even if I could match ratios. Rear fenders, loader brackets, etc get in the way. It's already pretty close.

I've been thinking about this for a few days. If you can't go larger you can still go wider. On my F935 mower I swapped out the 23x8.50x12 tires for a set of 24x12x12. (I just had the rims made wider) I just run a little bit lower air pressure because of the wider tire but what a difference in the ride in the rough areas of my lawn.

 

[4570Man]

Loader is always off when mowing. No I havent upgraded the seat yet. But if it's too rough for me to keep but in seat it's too rough/hard on tractor. Don't wanna snap an axle or bust a spindle.

I would like to upgrade the seat....I already put a nice grammar on my ZTR. Just waiting on my contact that works on forklifts to hook me up again.

The loader makes a lot of difference in ride and it’s surprising how many people won’t take it off.

 

[LD1]

The loader makes a lot of difference in ride and it’s surprising how many people won’t take it off.

Yes, huge difference in ride. Some of the blowouts I have hit if I had the loader on I'd expect a snapped front axle with the added weight.

And it's cumbersome mowing in/round tight areas, adds another ton to trailer around for no real purpose.

Takes 5 min to drop loader. There is no reason at all to leave it on IMO. The only time I do is if someone ALSO wants some loader work done.....or pays to have me shove trees up along fence lines before mowing