Advice on Hydrostatic Transmission vs Gears

[duffer]

I've got over 2000 hours on my HST. Not one transmission problem, and I've worked it VERY hard, as well as the loader.

I've used shuttle shifts and they're OK. I grew up with gear tractors and trucks and I don't think I'd want one for tractor work, especially with a loader. But that's just me.

For the sake of your kids who probably did not grow up with geared machinery, the HST will work better for them IMO.

 

[dodge man]

I’ve run both but mostly hst. The gear tractor I ran I remember thinking this isn’t so hard but I was also discing a field a running a cultipacker on an open field and just turning around at the end. I think most people are going to prefer an hst for most homeowner type use.

 

[bsekf]

Very little experience with a Hydrostatic, but I would get tired of having to push with my left foot all the time. So I would want cruise control. Nothing under 50 hp and a 4 range trans. Take a look at the Yamar with a "sort of" CVT.

Your kids???? If they are going to around equipment, they better know how geared equipment works.

 

[jyoutz]

In my experience that only happens with the heavy 24 hp tractors that only exist because they’re trying to beat the epa emissions regulations. If you have enough power the HST works just fine.

This^^^^

 

[hayden]

Hydrostatics are extremely controllable, but hugely force limited compared to gear tractors. In my experience based on more than 10 gear or hydro tractors, you will always encounter situations where you cannot apply enough "go" in any range to spin the wheels on an HST. Up to that point you are happy. After it you feel betrayed -- and maybe stuck.

That hasn't been the case with any of the three Kubotas that I have had. In low gear, thy have all been able to spin the tires without stalling the engine.

 

[bdhsfz6]

I've owned seven tractors since 1979, 6 with HST. No trans trouble in over 10,000 hours. I burned out the clutch in the one gear tractor I owned and went back to HST.

Gear or HST depends a lot on what work you do. If you run in fields at constant speeds, a gear tractor would probably be best. If you do a lot of maneuvering and loader work, an HST can't be beat. An HST would also be easier for the wife or kids to use. Otherwise, it's largely a matter of preference.

Keep in mind, the PTO HP is somewhat reduced on HST tractors so you may need to go a size up in engine HP, depending on your implements.

 

[SPYDERLK]

That hasn't been the case with any of the three Kubotas that I have had. In low gear, thy have all been able to spin the tires without stalling the engine.

So, you are still in the happy stage prior to where you are forced to make allowances for the HST relief pressure setting. Somehow I always find that point. Its usually verry inconvenient.

 

[oldnslo]

So, you are still in the happy stage prior to where you are forced to make allowances for the HST relief pressure setting. Somehow I always find that point. Its usually verry inconvenient.

Most CUT tractors have two or three range gear type transmission behind the HST. In low range the HST should spin tires same as geared tractor. In mid range on 3 speed they may or may not spin tires same as geared tractor in middle gears. High range rarely spin on decent footing same ad geared tractor.

The big difference between HST & gear is variable speed control of HST without changing gears.

Try putting your gear tractor in a gear that travels same speed as HST at full speed ahead. Then compare pulling or pushing performance. HST may slow sooner but it should either spin the tires or stall the engine same as gear.

 

[SPYDERLK]

Most CUT tractors have two or three range gear type transmission behind the HST. In low range the HST should spin tires same as geared tractor. In mid range on 3 speed they may or may not spin tires same as geared tractor in middle gears. High range rarely spin on decent footing same ad geared tractor.

The big difference between HST & gear is variable speed control of HST without changing gears.

Try putting your gear tractor in a gear that travels same speed as HST at full speed ahead. Then compare pulling or pushing performance. HST may slow sooner but it should either spin the tires or stall the engine same as gear.

Good advice for someone who does not fully understand the issue. It will not solve the problem I stated. The issue, mainly, is that the HST - at relief - will dump all energy stored in the rotating mass of the engine, and the energy it is producing while running, into the hyd sump. The relief is absolutely necessary due to the zero to max speed control. Right there at 0+ you have infinite "mechanical advantage" to provide very low hyd flow at "infinite" pressure, enabling infinite torque - even with a small engine. You wouldnt even know it til it broke. This situation cannot be allowed.
A gear trans positively dumps its energy to the wheels, or the clutch slips, or it breaks. The mechanical advantage is always finite and constant in accordance with the gear ratio. HIGH overload transients can be supported because a good safety factor must be built in to survive even normal use in such a "direct" drive system. All bets are off with creeper gear ranges tho. Mechanical advantage there is astronomical.

 

[oldnslo]

Good advice for someone who does not fully understand the issue. It will not solve the problem I stated. The issue, mainly, is that the HST - at relief - will dump all energy stored in the rotating mass of the engine, and the energy it is producing while running, into the hyd sump.

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.

The relief is absolutely necessary due to the zero to max speed control. Right there at 0+ you have infinite "mechanical advantage" to provide very low hyd flow at "infinite" pressure, enabling infinite torque - even with a small engine. You wouldnt even know it til it broke. This situation cannot be allowed.
A gear trans positively dumps its energy to the wheels, or the clutch slips, or it breaks. The mechanical advantage is always finite and constant in accordance with the gear ratio. HIGH overload transients can be supported because a good safety factor must be built in to survive even normal use in such a "direct" drive system. All bets are off with creeper gear ranges tho. Mechanical advantage there is astronomical.