Help to hook up Prince flow control valve

[memphismark]

Hey guys. I am desperate for an answer. Keep in mind I am a hydraulics novice if you are inclined to answer back. I have a Bobcat 753 with an auger drive unit that I want to use to drive a large 3 yard concrete mixer I made (I have a complete welding/machine shop). It turned out to be a bit to fast to mix with. I was sold a Prince Hydraulic flow control valve with relief, model RDRS 175-30, and was told this would easily reduce my speed. My question is, if I connect the Prince valve inline to the auger motor as normal, do I have to use the return port on the new valve and connect to some kind of reservoir? It has three ports. It's a fully adjustable valve by the way, from slow to fast. The Bobcat has two auxiliary hoses. Flow to motor, and return to reservoir obviously. If the new flow control valve is inserted in the flow to the motor hose, will the auger motor not just use the amount of fluid pressure it wants (depending on flow control valve position, slow or fast), move fluid thru the motor and back to reservoir thru existing return line, or will the pressure build up at the flow control valve have to be bypassed by using the port on the valve? If the valve return port has to be used, is there a way to return it to the existing Bobcat fluid reservoir? (and not have to fabricate and new auxiliary reservoir?) If yes, how would I do that? I would soooo appreciate some help here guys. Thanks so much. Mark

 

[J_J]

Here is how to connect it.

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Scroll down to applications.

CF - Controlled flow goes to hyd motor.

EF - Excess flow should go to tank.

I believe the relief valve is set to 1500 psi, at 10 GPM. You will need to put a load on the motor and crank the pressure up to whatever you need

Your hyd motor will develop the pressure determined by the load.

Your relief will unload when you get to the set pressure.

What is your normal flow in GPM's on the Bobcat?

 

[memphismark]

Thank you so much for you link. It looks like I can block the return port on the Prince valve if my Bobcat 753 is a "closed center system", what ever that is!!!
Or, if the Bobcat has a "pressure compensated pump" Would you have any idea what I have or how I might find this out? Again, greatly appreciate your help my friend. Mark

 

[J_J]

I believe you have an open center hyd system.

The return from the hyd motor has to go back to tank.

This is what you have for hyd.

Hydraulic System
0753
System Relief @ Quick Couplers 2550 psi
Auxiliary Std Flow N/A
Auxiliary High Flow 11 GPM

Bobcat Historical Specifications - Bobcat Company

Your valve will work to some degree, but you should have purchase the RD-175-16 GPM valve.

When you handle is at half way on the RD-175-30, you are in full flow.

Logically you would want to match your valve to the system hyd flow.


Do you not have a motor spool valve in the boom aux hyd.

Do you have a manual for your Bobcat?

I have one for my Case 1845c that covers every nut and bolt from front to back and options like BH.

Is your Bobcat a 753H, if it is, your flow is 22 GPM.

Skid Steer Loader Historical Specs - Bobcat Company

 

[oldnslo]

If you run your Bobcat at idle is the mixer speed still to fast?

 

[memphismark]

Unfortunately yes. Thank goodness I only need to slow it down by 15-10 rpm. I just can't seem to be able to determine if I have an open or closed center system, or a pressure compensated pump in order to determine if I can block the "return" port on the valve, or if I have to find a way to return fluid to the Bobcat fluid tank, or worse, make an auxiliary tank to stick in the system some where. Any thoughts.
Thanks much. Mark

 

[J_J]

This guy says the controls are open center.

Bobcat 753 F series trouble - Page 2

There is a way to determine whether it is open or closed center hyd system.

Find a return line and see if there is fluid flowing when the engine is running. With all valves in neutral, you will have flow, and that system is open center.

If you do that to a closed center system, the fluid is blocked when all valves are in neutral.

You could have slowed the flow with a flow divider valve. like this.

2/30 GPM PRINCE PRIORITY FLOW DIVIDER W/RELIEF

This will give you 2 GPM for the auger.

If you want reverse, you will have to shift hose around.

 

[Ivan49]

I have the same type of valve except mine is a 175-30. I am goning to use this to contol the speed on an conveyer. If I take the third line and Tee my return line off and add the line from the valve to it. Will this work. Sorry to hijack this thread

 

[J_J]

His valve is the same as yours.

What are you trying to do with the EF fluid.

The EF fluid can go to a return line which is tank, or feed another valve.

 

[memphismark]

That's what I'm thinking I may have to dol. Tee off of or into I should say, my Bobcat return. Is this sound logical anybody! mark

 

[Ivan49]

His valve is the same as yours.

What are you trying to do with the EF fluid.

The EF fluid can go to a return line which is tank, or feed another valve.

I want to use it to control the speed on my wood elevator. Right now it is to fast

 

[memphismark]

How would I go about determining if fluid is in the line? I have the standard Bobcat flat-faced hose quick connects. Also, I would assume if it (the return line) were under pressure, it could be dangerous to try and push on the connector end with a screwdriver or something to see if it squirts out. What do you think the best way to test a return line safely. Again, I'm a complete hydraulics novice. Thanks for your response. Mark

 

[J_J]

You should look for a return hose close to the tank, remove it and place in a bucket, start engine and see if fluid flows into bucket.

Only do this at idle for a few seconds.

A hyd gage might help you troubleshoot your hyd system also.

A closed center valve will usually will have standby pressure with all valves in neutral, and nothing going to tank through the return hose. The return or OUT hose is usually reserved for cyl expended fluid.

Your return line should not have very much pressure, as back pressure is not desired.

 

[memphismark]

I'm going to give this a try after the holiday weekend. This is the most comprehensive advice I have found about my specific issue. Thanks so much for your follow ups. It is such a help when you are out of your element on a particular subject to have someone take the time share their insight and guidance. I really do appreciate you. Thanks again. You have done your good deed for the day. To be continued....... Mark