hydraulics question

[ebeacham]

Where is the relief valve? Does this valve have an adjustment which I could use to raise system pressure?
Will raising system pressure cause my loader to cycle faster?
I know I should be taking a hydraulics 101 course, but asking you guys is easier and much more fun.

 

[hazmat]

Eric,

I don't know where the relief valve is, but it should be adjustable. Upping the relief pressure will not make your loader cycle faster. There are two factors in hydraulics, pressure (PSI) and flow (Gallons per minute or GPM). Increasing pressure will not speed up cycle time, but will increase the force applied. Increasing flow will speed up the cycle time.

An analogy (I hear I'm famous for my examples on TBN) is filling a 5 gallon bucket with a hose or a pressure washer. The hose will fill it faster as it has higher flow (more GPM). The pressure washer will knock it around because it has higher pressure.

If you run the engine faster, your hydraulic pump will put out more GPM, thus faster cycle time.

I've been looking for a good hydraulics handbook myself, The two I've read from the local library leave a bit to be desired. If I find a good one, I'll be sure to post it here for everybody's learning enjoyment.

 

[WVBill]

The question of "a good book on (insert subject here)" comes up every now and then here on TBN.
A good source of FREE information can often be found at the following web site.
Here, for example, is <A target="_blank" HREF=http://www.adtdl.army.mil/cgi-bin/atdl.dll/fm/5-499/toc.htm> Army Field Manual 5-499 "Hydraulics"</A>. There are many other texts applicable to "tractoring" located on that Army website.

 

[rdbrumfield]

I would not adjust the pressure relief valve on the tractor. Besides writing off the warrantee it could cause damage to the system.
For other systems, the relief valve is built right into the spools. It generally looks like a bolt with a slotted head for a screwdriver with a jam nut on it. It will be near the input line of the spools. There again, be sure to have a guage on a pressure port when you adjust it. Don't overdo it, it will not make anything work faster, just bends things better.
The pic will give you an idea of what to look for.

 

[rdbrumfield]

Didn't notice until I looked at the pic, excuse me for not being more politically correct.

 

[ebeacham]

Quite all right, besides; I'm used to it /w3tcompact/icons/grin.gif

 

[hazmat]

Bill thanks for the link. It's better than the ones I've seen. Might have to print that out (when nobody's looking) at work

 

[Mrwurm]

Great Manual. I may have to print a copy and store it in the restroom (library).

 

[jrlichina]

The relief valve on most tractors is built into the main 3-point control valve since it is the starting point of the tractor hydraulics. Additional control valves are added down stream from this point. The relief valve is usually in the form of an internally adjustable type. Instead of using a screw to adjust the relief pressure the use of shims are needed instead. This makes changing the setting a bit more difficult. The shims are available in various thicknesses to adjust as needed. Most systems have an operating range specified in the service manual. You should check the system pressure first to see if you are on the low or high side of the range. It is then up to you how much you'd like to increase the pressure. But be very carefull as serious system damage could result if raised too high. Going up a few hundred pounds would most likely be ok since there is always a safety margin built into the strength of the system(like O-rings, hard lines, hoses, etc.). Then there is always the warrantee issue if you still have time left.