Hydraulic pressure

[Oxfordcar3]

Have a 1989 terramite t-5b hydraulics don't have a lot of power seem to set off relief valve with very little force on any function I hooked up a gauge and have 2100 psi however the relief valve is turned all the way in I changed filter an fluid no change next changed relief valve still no Change I had to set new relief all the way I to get 2100 psi
Soy question is whats next ? Pump ? Should I have rebuilt or buy new if rebuild is an option how hard are they to rebuild I don't have a lot of hydraulic experience if I should have it done by a shop does anyone know we're in ct to have this done without paying through the roof

Thanks for your help

 

[J_J]

Most data says you should be using engine oil in the 10W-40 range. Check with Terramite to be sure.

This is the hyd data from a T5C

HYDRAULIC SYSTEM FOR BACKHOE & ENDLOADER:
Flow = 7 GPM
Pressure - 2400 psi
7 GPM at 3600 RPM

New, the pressure was 2400 psi

If your hyd is open center, there needs to be a free and clear path to the tank with no or little back pressure.

You might check the back pressure. It may sufficient to reduce your overall pressure.

If the relief is going off, that means the hyd is working up to the relief setting.

Terramite T5C

If your relief screw is turned all the way in, it is what it is.

For the age of the machine, 1989, you are only down 300 psi from a 2400 psi max.

You could have same small internal hyd leaks.

You might try removing and inspecting, and cleaning the relief valve.

 

[Oxfordcar3]

Per terramite service when I changed fluid I put in 15/40 oil I replaced the relief valve thinking maybe it was worn but had no effect still could only get up to 2100 psi I realize it's only 300 psi less than when new however loader and backhoe have very little power

 

[J_J]

Then you have some internal leaking going on, in the cyl themselves or the valves.

When you are working the hydraulics, are they going into relief often.

You can test both valves and cyl for leaks, just takes time.

Even a new pump may not help if the above are leaking.

There are ratings for the loader and BH, have you verified the figures for your loader and BH? If the manufacturer says you should be able to lift 1000 lbs with a certain bucket, and you lift 950, that would be within range of specs, however if the loader can only lift about 600 lbs, then you have a problem.

Recommendation, remove pump and have tested, but consider this, is 300 lbs reason to replace pump.

You can test the cyl and valves for leakage.

 

[J_J]

On the T5C, I noticed that the hyd go through the BH valve first, then to loader valve. Your main relief is on the BH valve.

Did you set both relief valves the same.

If you can, set the relief valves at about 50 psi below pump max pressure.

 

[Oxfordcar3]

When working bh sets off relief valve with little strain in my opinion
Bh relief valve no didn't set was led to believe the loader was the only one

 

[Oxfordcar3]

How would I go about testing valves and cylinders

Thanks for all your input

 

[J_J]

How would I go about testing valves and cylinders

Thanks for all your input

Do one cyl at a time. Remove the base end hose on a retracted cyl. Select the lever position to retract the cyl. If fluid continues to exit, the seals are leaking/bypassing.

You test the other end of the cyl by installing the base end hose and fully extend the cyl rod. , then remove the rod end hose and try to extend the cyl rod. If it leaks continually, the seals are leaking/bypassing.

You have to have known good cyl to test valve. So if the cyl are good, then remove the tank port and move lever to retract. If fluid continually flows, the valve spool is leaking. Check both ends of spool

You should test all spools in the valve. Try and stay below the relief setting. If you make the pressure go above the relief setting, fluid will flow out the tank port.

If you do not have the capability or know how, you can take each item to a hyd shop for testing.

Be careful when doing all this. If you make a mistake you will spray hyd fluid everywhere. Wear safety glasses and have clean up material available.

If you do it your self, you will save about $60 or more per hour.

If you don't have a gage test set, you can make one up like these.

 

[J_J]

The relief valve in an open center hyd system is usually in the first valve in the series flow path.