Forklift hydraulics only works when I step on gas? WTF?

I have one forklift (Cat TC60C).
The forklift drives and works in general. However, at idle speed, the hydraulics does not work at all -- I have to step on gas to, say, lift
the forks or tilt.
I do not really understand how that could be the case, any ideas?
i
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The pump is worn?
-jsw
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On Fri, 13 Mar 2015 05:58:06 -0500, Ignoramus24975

Clutch in the pump drive?
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There might be a clutch or a motor-speed operated relief valve, to prevent lugging at low rpms.
LLoyd
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Ummmm.... actually, I failed to ask the very first question anyone should ever ask: Did it ever work differently than this?
Lloyd
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On 2015-03-13, Lloyd E. Sponenburgh <lloydspinsidemindspring.com> wrote:

It never worked differently for me, I bought it only 3 months ago from a closed plant.
i
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Well... then maybe it's a "feature" instead of a problem.
Lloyd
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On Fri, 13 Mar 2015 05:58:06 -0500, Ignoramus24975

I wonder if it has a hydraulic pump keyed to engine rpm, or a pump which is leaking so badly at low rpms, it can't perform. Ask CAT if you don't have a manual for it which states something like that.
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Replace the pump or increase the drive ratio.
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On Friday, March 13, 2015 at 6:58:12 AM UTC-4, Ignoramus24975 wrote:

Most of my experience is with 36 volt electric forklifts 4+ decades ago in the USN. But more recently (1-3 decades) I used LP-fueled ones occasionall y in moving lab machinery at the school where I taught.
In my experience, it is entirely normal for an engine driven hydraulic syst em to respond sluggishly at idle, since the pump speed is proportional to c rank speed. This results in low flow volume, and less output pressure. It was normal for me to shift to neutral and step on the gas to get faster / m ore hydraulic response from the school's forklifts. Especially loaded, the hydraulics moved quite slowly at idle. These were not high-hour machines, s o I assume they were functioning as designed.
My guess, going from minimal info, you're seeing the effect of wear on the pump and maybe valve spools. But check your fluid level, and look around fo r a spin-on hydraulic fluid filter. If there's one, replace. If you're ana l about it, send an oil sample for analysis.
You might also do a simple leak-down test. Pick up a load at at least 1/2 capacity, switch off, and see if it descends slowly. This'll give you an i dea of the general condition of the hydraulics. If it stays up reasonably w ell, you don't have much wear (but don't get under a load, ever).
Jim H.
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