Hydro Power Loss on Hills-Brush Hogging

dbk123 · May 1, 2007

Hi,

I am considering a hydrostatic tractor in the 40-45 HP range. I will be running a 6' brush hog on some fairly steep terrain. I know that hydro transmissions take a few HP, however, I am wondering if the horsepower loss increases as additional power is required to push the tractor up a steep hill?

I currently have a gear tractor and, of course, use a lower gear so that the tractor has sufficient power on the hills.

Thanks,

-dbk123

RFB · May 1, 2007

I run a Kubota L5030 HSTC on Idaho "hills", pulling a 7 foot offset disc, and an 8 foot triple-k spring-tooth cultivator. I also use it to push fairly big snow with a 7 foot blade. I have never run out of power. With HST, when speed/rpms start to decrease, simply back-off the pedal until you maintain constant work-range rpm.

I have experienced zero negatives of HST and would never switch to banging a shuttle.

jinman · May 1, 2007

dbk123 said:
I currently have a gear tractor and, of course, use a lower gear so that the tractor has sufficient power on the hills.

Hydrostatic transmission tractors normally have two or three ranges that are actually gears. Within those ranges, you have as small an increment of power change as you can produce with a tiny movement of the pedal. Think of the HST as an unlimited range of speed from 0 to maximum for each range. I'm sure with your hills you can find a mid or low range that will work just fine. Your 40-45 hp tractor will operate that 6 ft cutter just fine on any hill you can safely traverse.

Some HST newbees treat the HST pedal as a "gas pedal" and have to learn that it is really a gear-shift pedal with a continuously variable ratio. A low range with slight pedal movement will provide the most power to the wheels. A large movment will spin the tires or cause the HST transmission to go into pressure bypass and stall. You will learn quickly where these limits are.

In my opinion, there is no safer transmission type to have for working on hills. I do things with my HST that I would never consider doing with my gear transmission tractor.

_RaT_ · May 1, 2007

dbk123 said:
Hi,

I am considering a hydrostatic tractor in the 40-45 HP range. I will be running a 6' brush hog on some fairly steep terrain. I know that hydro transmissions take a few HP, however, I am wondering if the horsepower loss increases as additional power is required to push the tractor up a steep hill?

I currently have a gear tractor and, of course, use a lower gear so that the tractor has sufficient power on the hills.

Thanks,

-dbk123

You will see the same thing with a hydrostatic drive as your gear when going up hill. You can choose to either go down a range or simply go slower up the hill to avoid over loading the engine. It is really quite easy. I was on nothing but hills and just backed off the HST pedal when going up hill or going through very thick and wet grass. I never shifted to low range. So to answer your question, I do not know for sure if HP loss in a hydrostatic drive is progressive as the load increases, but then, it never mattered, it was not an obstacle to performing the work. The real bonus is the instant response and ability to get power back immediately by backing off on HST demands. That helped out enourmously on hills and the thick and wet stuff.