Broke Hydrostat twice? Why?

[oldpilgrim]

this past winter, the fluids were very cold and the fel would react very slowly until the fluid got warm.

I read somewhere that if the bucket is put into full dump mode and held there, the relief would kick in and warm up the fluid faster as it squirted thru a smaller opening.

Is this true? It seemed to work. Is this a bad thing to do?

Very interesting thread.

 

[oldnslo]

this past winter, the fluids were very cold and the fel would react very slowly until the fluid got warm.

I read somewhere that if the bucket is put into full dump mode and held there, the relief would kick in and warm up the fluid faster as it squirted thru a smaller opening.

Is this true? It seemed to work. Is this a bad thing to do?

Very interesting thread.

FEL operating speed is a function of oil flow rate. If it is running slow from cold oil this is an indication that the pump is being starved of oil or cavitating. Running the pump at max pressure (over relief) will shorten the life of your pump considerably.

 

[oldnslo]

this past winter, the fluids were very cold and the fel would react very slowly until the fluid got warm.

I read somewhere that if the bucket is put into full dump mode and held there, the relief would kick in and warm up the fluid faster as it squirted thru a smaller opening.

Is this true? It seemed to work. Is this a bad thing to do?

Very interesting thread.

FEL operating speed is a function of oil flow rate. If it is running slow from cold oil this is an indication that the pump is being starved of oil or cavitating. Running the pump at max pressure (over relief) under these conditions will shorten the life of your pump considerably.

 

[GManBart]

FEL operating speed is a function of oil flow rate. If it is running slow from cold oil this is an indication that the pump is being starved of oil or cavitating. Running the pump at max pressure (over relief) under these conditions will shorten the life of your pump considerably.

The manual for my backhoe says that if the hydraulic light comes on, it means either the filter is plugged, or the fluid too cold. If it's due to cold temps, they direct you to put the loader into relief and hold it there for something like 15 seconds at a time, and do that several times, to heat up the fluid until the side of the reservoir is warm. I can't imagine they'd be recommending something that would shorten the pump life.

 

[Sysop]

There is nothing wrong with detented AUX valves....I need them for running
a backhoe, or a hyd PHD, or hyd concrete mixer. Mine is very hard to
accidentally engage. That's really the issue.

I like the solution on my tractor where it is a self centering valve, but they put a little hook on the platform of the tractor you can engage to hold the valve when using the backhoe or something requiring full time flow.

 

[dfkrug]

The manual for my backhoe says that if the hydraulic light comes on, it means either the filter is plugged, or the fluid too cold. If it's due to cold temps, they direct you to put the loader into relief and hold it there for something like 15 seconds at a time, and do that several times, to heat up the fluid until the side of the reservoir is warm. I can't imagine they'd be recommending something that would shorten the pump life.

That's interesting. Does CASE recommend that procedure for the 580?

Of course, running the implement pump circuit on relief will warm up the oil, fast. But sucking cold oil into
the pump can cause cavitation, as OnS says. I have not seen that recommendation in any tractor manual
I have read, and I do read them. They all recommend letting the tractor warm up for a while before
using it.

My tractor when cold (50F or so) protests when I try to put much of a load on the HST too soon. A light
on the dash comes on that looks like a horizontal squiggle with circle around it when I use the go-pedal
too soon up even the slightest grade. It comes on steady, or flashing. No info on this light in the OM at all.

In terms of manufacturer recommendations, I remember reading a Caterpillar manual for an early 30s Cat
28 dozer. It recommended lighting a fire under the engine to help with warm-up. Wow.

 

[DavesTractor]

This is a great thread. The OP is a customer any dealer would want. Yes, dealers have good customers and not so good, just like customers have good dealers and not so good.

Of course this is already solved by people more knowledgeable than I, but we cannot over emphasize the amount of heat generated in a system that is bypassing. One formula I saw is BTU/HR = 1.5 x PSI x GPM. PSI is the difference in pressure from the relief valve to where it is going, the tank in this instance. Relief should be around 2400 PSI in most small tractors. GPM is the pump flow I think, maybe 5 gallons on this tractor at 2000 rpm. Do the math and you get 18,000 BTU/hr. Lot's of heat.

Keeping the oil cooler clean is important. Making sure the relief is not open due to a remote in detent is critical. I like the ideas mentioned of securing the lever, but also putting a loop hose in just in case. Great idea. Finally, installing a heat gauge in the tank would also be smart.

 

[dfkrug]

Keeping the oil cooler clean is important. Making sure the relief is not open due to a remote in detent is critical. I like the
ideas mentioned of securing the lever, but also putting a loop hose in just in case. Great idea. Finally, installing a heat
gauge in the tank would also be smart.

I have no problem with any of those methods to avoid this problem. There are a lot of ways to break a tractor.
I especially like an oil temp gauge cuz that is always working and does not require any special procedure to
avoid putting a RV into more than momentary relief. It also guards against other things that could raise temps.
It also could tell the operator when it is OK to do some work (oil warm enough).

From your perspective as a dealer carrying more than one brand, Dave, do any of them sell internal parts of
their HSTs?

(BTW, I told Bob to stop by your place to oogle new tractors if he decided to take the I-5 (faster) route home.)

 

[DavesTractor]

We can show Bob some cool tractors. We have a DF tractor here that is just a little longer, but no wider or taller than a 30 HP Mahindra and it is 96 HP. Made for vineyards or orchards. Dangerous to stop here though, it often causes one to buy a new tractor!

Our OEMs do not sell HST parts. Just complete units.

 

[Coyote machine]

I second the let it warm up to temp thinking instead of, even if recommended by a manufacturer, idea of throwing the system into relief as a way to raise the trans fluid temp. From my perspective, I want a long life from my tractor, so giving it a few minutes to come to operating temp is time well spent doing a walk around to see if there might be something that might need attention, low tire pressure, torn or leaking hose, etc.

And consciously putting a HST into relief to bring oil temp up is not likely to do any real harm, partly because the oil is already cold and will have to get to temp to do it's tasks. BUT the accidental knocking a lever into relief, likely when the oil is already at operating temp is a whole different situation, especially if it is left in relief for unknown, possibly extensive amounts of time. Relief is just that, something that is meant to protect, not meant as a means of pulling excess heat constantly.

I hang my 'loop hose' near where my tractor sits, and whenever I remove my backhoe it goes on to protect the circuit from overloading the HST. It's cheap and easy 'insurance' against what could otherwise be a very expensive failure. YMMV.