Hydaulic pump

dmccarty · Dec 13, 2000

I'm curious about two things in this thread, overloading the dydaulic systems and HST/Engine opereration.

As I said in my previous example, if I try to lift The Stump That Won't Move, either with my FEL or backhoe nothing will happen. I don't stall the engine and I don't hear a relief valve screaming. I had assmued that a relief value was opening, I just don't hear it.

I have never stalled the tractor engine with the FEL or the backhoe even though I have I certainly seemed to have given it reason. I'll have to pay more attention but I don't notice any changes in the sound of the engine especially with the backhoe.

My second thought brought out in the thread is about HST's, throttle position and my floor accelerator. I usually run the engine at 1500 RPM just moving stuff around. If I start pushing up a pile of timber or lifting something I'll "step on the gas" for some more ooomph. But from what you HST guys are saying you can't "step on the gas" because you don't have a floor throttle.

If an HST tractor does not have a throttle does it need one? And conversely does MY tractor need the floor throttle? As I remember the torque curve most of the oomph is around 1500-2000 RPMs so if I'm already in the sweet spot of power, using the floor throttle might actually give me less power!

Does this make sense? Do I need more Coffee? If I'm short of coffee is it because I don't have one of these SuperDuper Tractor Mugs Harv and Marc are playing with?

Thanks!
Dan OnHisSecondCupOJoeThisMorning McCarty

RobS · Dec 13, 2000

I use my floor throttle more often for loader work and it's not for oomph but for flow. I keep the dash throttle set at about 1500 (sometimes less if I'm doing "detail" work) but give it some additional RPMs when I want to speed up the loader. My tractor is GST.

Rob

Rowski · Dec 13, 2000

Question-> What happend to a tractor with HST if you are in highest range, at pto RPM, HST pedal all the way down (forward motion) going up a really steep hill (like on the road)? Will the tractor stall the engine? Just a curious gear head /w3tcompact/icons/frown.gif who has to stop in the middle of the hill to shift down /w3tcompact/icons/frown.gif.

Derek

Bird · Dec 13, 2000

Derek, I've never been rolling in high range, like you're asking about, and come to a hill too steep to keep going, although some have sure slowed me down. However, when I had the B7100, I did get down in a hole (dried up stock tank) once (actually twice) and started out and it just wouldn't go even though I eased down on the pedal. I wasn't moving, wasn't spinning the wheels, but sounded like I was really loading the engine and I knew if I pushed the pedal any farther down, I would have killed the engine. And then it dawned on me that I was in high range, 2WD; shifted to low range and away I went. So I've no doubt the answer to your question is, yes if you kept the HST pedal down and the hill got steep enough, you'd stall the engine much as you would with the geared tractor.

Bird

MChalkley · Dec 13, 2000

Dan - The HST model Kubotas have a hand throttle only, so if you need to "goose it" a little, you just use your right hand instead of your foot. It's not quite as convenient, but generally you only have to back off a little on the HST pedal to finish the job, so it gets done about as quickly and you save a little fuel, too.

I've said many times that I get a lot better fuel economy (about .15 gal/hr better) with my L4310HST than I did with my previous L3600GST, even though the L4310HST is rigged to be much heavier and, of course, has a bigger engine. I'm sure this is because I'm matching the rpm to the job better and not using the throttle like you do on a car anymore. Diesels don't really like to be treated that way. They perform much better if you set them to the right rpm and leave them there. If it's lugging too much, you're in the wrong gear, and it's a cinch to change to a "lower gear" with the HST - just ease up on the foot pedal a bit and, if you have to, switch to a lower differential range.

MarkC

MChalkley · Dec 13, 2000

Derek - As Bird said, yes, the HST will usuallly just stall the engine if you keep the pedal all the way to the floor when it's too high a gear. Often, though, if you have the highest horsepower model for a given transmission and the engine is wound up pretty well, it'll have enough power that it won't stall, but since the "gear ratio" is too high, the pressure relief valve in the transmission will pop instead. On the lower horsepower models, it'll stall.

In either case, though, all you generally have to do is back off on the HST pedal a bit to "lower the ratio" and it'll work fine. With some things, like pushing into a pile of topsoil, you can't do it at all in high range and have to switch to medium or low.

MarkC

TomG · Dec 14, 2000

I don't know if you feel the hydraulics are working normally or not. In a normally working system, it is the relief valve that opens when the hydraulics stall. I suppose it's possible that yours can't be heard, but I think that would be uncommon.

However, there are various reasons why a loader would stall without hearing the valve. A standard pressure test would determine if the pump, relief valve and priority valve are putting out and holding adequate pressure.

Thomas · Dec 14, 2000

Derek,
I can do one of two things w/ my HST.
More throttle or a low range.
Between the engine and the transmission one will notice a warning sound that your not going to make. /w3tcompact/icons/frown.gif

I guess your out plowing this morning...yep looks like were are getting the left overs from the mid west...4 inches so far here. /w3tcompact/icons/smile.gif/w3tcompact/icons/smile.gif/w3tcompact/icons/smile.gif

Take care over there and stay safe.

Thomas..NH /w3tcompact/icons/wink.gif

Pete6114 · Dec 19, 2000

This is my first tractor and am learning how to use it properly.(120 hours on it now) I have been using the hand throttle at full speed when i clear snow, using the bucket and 6 foot blade at the 3-point. Seems to work best for me. When i cut grass, i use maby 1500-1700 Rpm. As far as fuel usage, i dont worry about it as a tank will get me a long way. LOVE DIESEL.
Should get me a car with a diesel engine too...

Pete6114 · Dec 19, 2000

This is my first tractor and am learning how to use it properly.(120 hours on it now and build me a cab from angle iron with plexy glass all around, which keeps me out of the wind and the snow out of my face.) I have been using the hand throttle at full speed when i clear snow, using the bucket and 6 foot blade at the 3-point. Seems to work best for me. When i cut grass, i use maby 1500-1700 Rpm. As far as fuel usage, i dont worry about it as a tank will get me a long way. LOVE DIESEL.
Should get me a car with a diesel engine too...