Hydaulic pump

[MChalkley]

Bird, methinks it's a possibility... /w3tcompact/icons/wink.gif

MarkC

 

[gordon]

HST pedal ====not the throttle===not the throttle===not the throttle, once I got that through my thick head after using a gst for so long I liked the hst better hands down. Whats that saying--If it ain't got a HST it's not for me
Gordon

 

[Pete6114]

I ment stalling the engine.

 

[Bird]

Pete, a lot of us have stalled the engine on our tractors with HST when we've used them a little bit wrong. If you're thoroughly familiar with the HST, then you can ignore this, but I'll try to explain (Mark could probably do it better).

You use the throttle to set your engine RPM, but I think there's a natural tendency to think of the HST pedal like an accelerator pedal; push farther down to get more power. Actually it's just the reverse. Pushing the HST pedal farther down is akin to shifting to a higher gear, and therefore, increases the liklihood of stalling the engine. When you need more power, you can increase the RPM with the throttle, use low range on the HST, and ease into the job with very little pressure on the pedal. When operated that way, you're highly unlikely to stall the engine; instead you will just spin the wheels.

Bird

 

[MChalkley]

Pete - Bird, as usual, beat me to it. (Nice job explaining, Bird.)

Since you were talking about the engine, you're in luck. Increasing the hydraulic pressure would only increase the likelihood of stalling the engine, if anything.

As Bird mentioned, I suspect your stalling problem is coming from using the HST pedal as an accelerator and not, as it in reality is, a transmission shifter. Just remember that when you need more power, you need to go slower. Just as you wouldn't shift a manual transmission into high gear to go up a steep hill, you can't floor the HST pedal to do it, either. Try to visualize the HST pedal as an infinitely adjustable manual transmission with low, or first, gear at the beginning of the pedal movement and high gear with the pedal all the way "to the floor".

Of course, you've also got a range selector which allows you to select a high or low gear (and, in the case of the L-series, a mid-range in between). Use the low range for heavy work (or if you're stalling the tractor in high range) and the high range for lighter, higher speed work.

The other thing to remember is that you should also set the engine rpm to a relatively constant rpm that's high enough to do the job. HST transmissions need an engine rpm above 1500 or so, and work best above 1800. Other than those minimums, set the engine rpm to the task at hand. Heavy loader work and work with PTO-powered implements often requires rpms close to rated PTO speed, which is probably around 2500 rpm on your tractor but drops as the size of the engine increases, because larger diesel engines, with their very long piston strokes, aren't capable of the higher rpms that the smaller ones are.

All that said, don't hesitate to ask any questions about anything that comes up, or anything that doesn't "feel right" when you're using your tractor. There's lots of folks here who've "been there and done that", whatever it is, and are willing to help. We may be apt to want to laugh with you, but not at you. /w3tcompact/icons/smile.gif

MarkC

 

[Pete6114]

Thanks a million guy's. You'r very informative and helpful

 

[dmccarty]

Pete,
Did Marc and Bird guess correct as to why the engine was stalling?

I don't have a HST tractor but if I put my FEL under a large unmovable stump and try to lift it nothing happens. The engine just does it thing and the FEL just sits there. Of course the stump did not move either which was the point of the excercise!

If I lock my backhoe onto said Stump That Don't Wanna Move its the same result. I can hold down on the appropriate control to provide hydraulic pressure and me, the tractor, the backhoe and the stump just sit there waiting for someone, meaning me, to do something else.

But no stalled engine.

This is more to Bird and Marc but whoever has The Knowledge is welcomed to spread it!

Do these fancy dancy HST tractors have only one throttle? I sure could see someone getting confused. My JD PowerReverser Tractor has two throttles, one on the dash as to be expected but also one of the floor for the right foot. It is like a car accelerator but the engine speed should be set by the hand throttle. The floor throttle is to give provide a short term RPM boost. I use to when "bull dozing" or scooping stuff in the FEL bucket. I thought the HST's had a way of doing something similar.

Edicate Me!

Thanks,
Dan HappyWithHisPowerReverser McCarty

 

[Bird]

Dan, I've used about a 50hp White, geared tractor, in the hayfields with the hand and foot throttle like you're describing. If it's a straight geared tractor, I like that arrangement. But with the HSTs, we only have the one hand throttle to set or adjust the engine RPM. Then there is the HST pedal (heel and toe for forward and backwards) and the farther down you press it, the faster you go, but as we mentioned, it's the equivalent of going to higher gears, but very smoothly with no shifting.

Bird

 

[MChalkley]

Dan - To add to what Bird told you, the reason I asked Pete if the engine was stalling was that, if it was, I suspected the issue he was dealing with was forward/reverse motion, and not FEL lifting/lowering/rolling/dumping. There would have to be something very, very wrong with a tractor to cause the engine to stall when you attempted to lift something too heavy (as in your "unmoveable stump" analogy). What I suspected was happening is akin to your pulling up to your unmoveable stump and attempting to push it over in high gear - a stalled engine.

MarkC

 

[TomG]

In hydraulic operations that are run purely from the tractor hydraulic pump, it's fairly common to stall a loader, backhoe, or even the 3ph. What happens is that the load is greater than capacity of the system, so the system pressure relief valve opens. In a normally working system, you can hear the relief valve sort of 'screaming' when it opens. It's a good sound to know, because the tractor shouldn't be run for too long when the relief valve is opening. It can over-heat the oil.