Advice on Hydrostatic Transmission vs Gears

[Too many Kubotas]

Hmm. Looks like I've been using my tractors wrong, always doing my very best not to spin tires. Maybe that's why their tires last so long?

If I want to spin tires I drive the Challenger. Although it's an automatic, not an HST, so not a great comparison.

 

[SPYDERLK]

On an HST the high pressure work port reliefs relieve the flow to the opposite work port not the reservoir. They also keep the system at full torque as long as the relief is active. Not sure why you think they dump energy unless you are referring to inertia of moving vehicle.

eek. That sounds like a like a quick fluid fry, circulating the oil straight back to the pump. The energy dump is across the relief valve. The fluid going back to the pump is then re energized as it is pulled through and forced out to whatever will take it. When the wheels wont turn a small amt leaks past the working elements in the hyd motor that drives the wheels leaving the remainder deadheaded and relieved continually at the relief. That isolated circuit will heat very quickly.

 

[oldnslo]

eek. That sounds like a like a quick fluid fry, circulating the oil straight back to the pump. The energy dump is across the relief valve. The fluid going back to the pump is then re energized as it is pulled through and forced out to whatever will take it. When the wheels wont turn a small amt leaks past the working elements in the hyd motor that drives the wheels leaving the remainder deadheaded and relieved continually at the relief. That isolated circuit will heat very quickly.

You are 110% correct that an HST in a stall going over the work port relief will get hot very quickly. That is why the more expensive system will have another pressure limiting valve on the control part of the circuit so the pump destrokes before work port relief setting. This again keeps system at max pressure but not create near as much heat at stall condition.

Some of the newer “E” style HST. Trannies may have this feature but I know my Branson with mechanical control swashplate does not.

 

[Shawn T. W.]

With a loader you can always make the tractor heavy. Iv never found an HST tractor that will spin wheels pushing and lifting with differential locked. Iv never found a gear tractor that wouldnt, at half throttle, even fully ballasted and counterweighted.
Maybe a 4 range trans on the hst would do it.

Well ... my Mighty Massey, which I call "My Little Baby Fergie"! Is Amazing then!!! A SCUT sized GC 1725 MB with a whole whopping 25 HP, and 2 range HST!

Here you can see she came to a tire spinning stop from a full 6' wide rear blade full of gravel ... Rear tires are filled, 4X4 with rear axle locked ... Bucket was only filled about 3/4 full as once I drop the blade on the ground, there is not much counter weight (ballast) on the back ...

So ... I believed if tires are spinning ... I needed more weight ... So, I added 70 Lb steel wheel weights to each of the rear wheels, and rigged up a way to add another 200 Lbs of steel weight lifting plates to the backhoe frame (since have added another 75 Lbs) ... Better, but still spun the tires to a stop on damp clay this time!

Even added 50 pounds to the floorboard, and made sure the fuel tank was full!!

If you can't spin a tire with a HST, either you aren't trying very hard, or doing it wrong! Sure I can "stall out" a HST, but can easily do that with a 535 HP semi-truck trying to be stupid starting out in high range with a full load pointed up hill ... Most tractors and semi-trucks aren't usually out doing smoke shows, but I've spun the tires on both!

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But to the OP - for the intended purposes you've listed, I'd say a HST would be the "better" choice. If you're doing a lot of ground engaging like dragging a plow to turn over ground for days/weeks on ended every year, a geared transmission would be a better choice ... For full disclosure I own two HST tractors, and much prefer a standard geared transmission in a semi-truck!