Setting Relief valve

kopeck · Nov 10, 2014

So I'm installing a new spool valve on my SM. The relief valve is set from the factory @ 1500 PSI. The live pump maxes out at 1200 PSI.

This is the only valve in the system, the relief suppose to go down to 1000 PSI but there no stop to say it's reached it's lowest value.

So my question is, since I don't have a gauge, just install it, and keep backing it off until the valve doesn't stall the engine at low idle or is there a better way?

K

leroy in ne · Nov 10, 2014

McMaster and other suppliers have 2000psi cheapy gages for about $10.00. not supper accurate or heavy duty but beat guessing

rustred · Nov 10, 2014

you definitely need a guage. how can a person guess in hyd's, like safety first. liquid filled gauges with a 1/4 " pipe thread are less than 20.00.

Dennis K (WA) · Nov 10, 2014

If the tractor only puts out 1200psi, the 1500psi relief won't ever come into play. Once 1200 is reached the additional will go to return. If I understand what you are saying.
A gauge will show all.
Dennis

Janicholson · Nov 10, 2014

We do not know that the pump has a built in relief at 1200psi. We know it will fail if used at higher pressures. The real issue is finding the valve is it exists, or installing a control valve with the relief built in, and setting it to 1200psi. I understand your reasoning, but I am pretty sure of these factors. Jim

redforlife · Nov 10, 2014

Adjust it down so you know for sure it is less than 1200. Then hook tractor up to a hydraulic equiped peice of equipment. If you don't have enough pressure, you know you are to low. Then simply adjust it up just enough to make your hydraulics do what you want. If you switch out equipment, it may need adjusted up a bit more if that particular thing needs more pressure, but atleast you know you are throwing to low of pressure for what you are doing instead of to much. You could eliminate the need for a guage this way, unless you are using something that is going to excede the 1200, which you shouldn't be using anyways.

mkirsch · Nov 11, 2014

Once 1200 is reached the additional will go to return.

Sorry Dennis but that is not even remotely accurate.

The distributor pump on a Super M does not have an internal relief, so the oil will just "deadhead." If you're lucky, it will stall the engine, but there is a good chance that it will shear the key on the hydraulic pump drive gear. Once you do that, the tractor will stall, but you won't be able to start it without removing the pump, fixing the key, and re-timing the engine.

kopeck · Nov 11, 2014

(quoted from post at 05:46:43 11/11/14)

Once 1200 is reached the additional will go to return.

Click to expand...

Sorry Dennis but that is not even remotely accurate.

The distributor pump on a Super M does not have an internal relief, so the oil will just "deadhead." If you're lucky, it will stall the engine, but there is a good chance that it will shear the key on the hydraulic pump drive gear. Once you do that, the tractor will stall, but you won't be able to start it without removing the pump, fixing the key, and re-timing the engine.

Yes, this is what I'm dealing with.

It's a SM with a engine driven pump that's using the belly pump as a reservoir, it does not have the stage II type reservoir with built in relief. I feel lucky that the first time I tried it I had it at it's lowest idle so when it stalled the engine I felt lucky.

I was thinking last night and I might have a gauge kicking around, I bought one for my splitter and I don't recall ever installing in. All I would need is a 1/2 to 1/4 bushing.

I'm planning on setting it to 1000 psi (the lowest it will go) and go with that. It's primarily going to be lifting my Saginaw 3-point hitch.

K

Dennis K (WA) · Nov 11, 2014

I guess I miss understood the original post. I took it that it had a relief at 1200psi which would make my statement true.
But, if it does not and the pump can only stand 1200psi then, yes, you need a gauge to adjust the relief in your add on valve.
Sorry
Dennis

pete 23 · Nov 11, 2014

If depends entirely on how the added on valve is hooked up into the system. The way we usually hook them up is in parallel with the original relief valve that is in the reservoir. The factory set up with the Christmas tree valve uses the relief in reservoir which is about 1200 psi as the Christmas tree valve does not have a relief valve. If he has his hooked that way the lower relief will control the pressure.When hooked parallel you have to lock the tractor original lever in demand positon. If he is running direct to his new valve, no parallel connection he will be utilizing the relief in his new valve. That pump will stand 1500 psi, no problem as it is same pump as a 450 and they will run to 1500 psi.

mkirsch · Nov 11, 2014

If he's using the bottom drain on the belly pump reservoir for suction, and running the return line into the fill port, there is NO relief valve in the system.

The spool valve will be the sole source of relief.

pete 23's right, that pump can do 1500PSI no problem. So, anything less than the factory setting is perfectly fine on the relief.

Setting Relief valve

kopeck

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leroy in ne

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rustred

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Dennis K (WA)

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Janicholson

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redforlife

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mkirsch

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kopeck

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Dennis K (WA)

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pete 23

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mkirsch

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