Hyd. Pressure

[pontiacman]

I am curious if anyone knows what the pressure should read on a 2009 5740C,
and if anyone has adjusted relief, a procedure.
Thanks

 

[Tul01]

I have a copy of the shop manual from TractorBarry(thanks again) it tells how to adjust the pressure(seems simple enough). I was thinking ours is low, as I couldn't lift a full pallet of wood pellets for the neighbor= 2000lbs. I've never had trouble with lifting anything before so maybe I have never asked it to lift to max. I was planning on checking the pressures, but haven't found out what they should be or picked up the equipment yet. I could email you the manual when I get home this weekend if you want.

 

[pontiacman]

I am having the same issues with large tight round bales. It will get them, but I have to roll the loader back to get the bale off the ground. According to montana the system should run at a working pressure of 2275 psi. I will test it and report back.

 

[Tul01]

I thought i had read somewhere of that vicinity, i just couldn"t find it thanks for the numbers.

 

[Tul01]

Got around to putting a gauge together to fit in one of the rear remotes. 2300 PSI.:thumbsup: Now I'm not sure why I'm only lifting 1500lbs?

Brent

 

[mwb]

Try removing a loader pressure line and check it there. Your supply may be capable of 2300 but maybe there is a problem with your actuator valve and that 2300 is not making it to the cylinders. I am not sure if there is a separate relief on the loader valve or not? If you check the pressure on a lift or curl circuit you will know for sure.

My 3940 (39hp) has increadible lift, your machine must have something wrong.

 

[Tul01]

Thats my next check, to be honest I had thought the overall pressure would just be set too low and now I have to do some real investigating. If it would only warm up above -20C. The loader really has been working fine pushing snow, I have done enough of it this winter!

 

[mwb]

I just checked your forecast (curious is guess) - at least you are not expecting snow :thumbsup: Stinkin' cold though.

My neighbor has the same tractor as yours, if it warms up for you and you are able to check it out let me know if you need any comparison measurements from his.

BTW, can you send me a copy of your manual? Neighbor might appreciate a copy. I will send you a PM now.

Thanks,
Mike

 

[J_J]

I am having the same issues with large tight round bales. It will get them, but I have to roll the loader back to get the bale off the ground. According to montana the system should run at a working pressure of 2275 psi. I will test it and report back.

The closer you get the material to the lift pins, you will be able to lift more. By curling up, you are doing just that.

A pressure of 2500 psi on a 2 in cyl will produce about 7864. The lever principle comes into play here, and the distance of the load to the lift points will dictate the actual lift force.

For each 100 psi increase, the force will increase about 315 lbs.

If you should raise the pressure 2500 to 3000, the lifting force will increase about 1589 lbs. I used these figures as a reference only.

This is computed with a straight on push. If the cyl is angled to the lifting device, the force will be less.

 

[mwb]

The closer you get the material to the lift pins, you will be able to lift more. By curling up, you are doing just that.

A pressure of 2500 psi on a 2 in cyl will produce about 7864. The lever principle comes into play here, and the distance of the load to the lift points will dictate the actual lift force.

For each 100 psi increase, the force will increase about 315 lbs.

If you should raise the pressure 2500 to 3000, the lifting force will increase about 1589 lbs. I used these figures as a reference only.

This is computed with a straight on push. If the cyl is angled to the lifting device, the force will be less.

I think his problem is that the lift is not strong enough but he is able to curl (only) enough to move it. That loader is spec'd at 2500 lbs to full height, 3000lbs to five feet. Round bales shouldn't be a problem!

 

[J_J]

He never did say if the relief activated when trying to lift that bale. I suspect either the bale weighs more than 1500 lbs, or he is losing the pumps ability and the cyl integrity to develop the pressure. Could also be the lift cyl are bypassing.

If you are correct with the lift force, then he is losing about 1000 lbs of usable force.

 

[pontiacman]

J_J,
The relief is not activated when I am trying to lift the bales, it just lacks a little OOMH. The bales are big (6x6 rounds), and I imagine I am losing (or the bale is gaining) quite a bit of leverage being as the center of the bale is approx. 4' from the pins.

 

[J_J]

Does the relief activate at the end of the stroke? The hyd gage will surely tell you what the problem is. As I said before, my pump was bypassing and reducing my load capacity about half. You could also take the pump off and have it tested.

Can you curl the load before you try to lift.

If I get under something heavy with the new pump, , and give it full power, the rear end will lift in the air.

 

[mwb]

My bet is the pressure relief on your loader valve is set low.

 

[J_J]

My bet is the pressure relief on your loader valve is set low.

pontiacman, said the relief doesn't come on, which means that if lifting a heavy load, the relief would be set too high, or not working and the relief would never activate.

Hypothetical:

If every thing is working good, and the relief is set to 2000 psi for the tractor to lift 1000 lbs, the relief would activate at 1010 lbs.
If the relief is set to 2500 psi, he might be able to lift 1800 If he can not lift 1500 lbs, the pressure is being lost somewhere. Same weight, same resistance to the pump and cyl.

That is why in a good hyd system, if you bump up the relief settings, you gain lifting force. About 315 lbs for each 100 psi increase. 500 psi increase in a good hyd system will gain about 1575 lbs.

 

[pontiacman]

JJ,
I can curl the load when I am unable to lift it vertically. It seems that a combination of the two functions (curl then lift) will get the bale in the air.
Where should I begin to troubleshoot if it is bypassing.
Thank you all for the great advice.

 

[mwb]

I am not sure how you would know if the relief is opening or not unless your relief 'screams' when venting. Mine is completely silent.

First thing I would do is put a pressure guage on your hydraulic line going from your valve to your lift cylinders. Just remove the quick-connect fitting and install the gauge on the rubber hyd hose (don't need cylinders connected) or install a matching fitting on your gauge. Try lifting or lowering with the gauge dead-ending the line and you will immediately know if the problem is the relief pressure. This needs to be done on the loader side of the valve (output), not on the supply side (input).

I doubt you are having bypass problems with the cylinders otherwise they would leak down all the time. You could have bypass in the valve but I am 99% sure the valve relief is set too low. The gauge test would take you three minutes to confirm the problem.

 

[pontiacman]

MWB,
I will try to test the pressure on the output side and report back.
Thanks for your help!

 

[pontiacman]

MWB,
If need be, what is procedure for adjusting the pressure relief.
Thanks again.

 

[J_J]

MWB,
If need be, what is procedure for adjusting the pressure relief.
Thanks again.

The hyd test gage goes on the input side of the valve. Just tee in to the IN port and leave the gage in place, and then any hyd operation will be reflected on the gage.

To adjust, remove the cap on the relief valve. and there should be a bolt/screw to turn down, or shims/washers have to be installed. Easy to do. If you need shims, ask your dealer what size shim will produce the effect you want.

Install gage, start engine, and read hyd pressure by fully extending the cyl. If screw type, adjust for correct pressure.

Turn off engine, to install shims as necessary.

Start engine, and fully extend and read the pressure.