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Active Contributor

Join Date: Aug 2010
Posts: 20

Which Circuit is Better?

11/29/2010 10:54 AM

Good day Sir

Because, in my town, it is very very difficult to buy the directional control valve accordance with design. So i usually the other type (not proper) to replace for the proper valve. So please help me to compare 2 circuit with the same function,THE SECOND VALVE is use to combine flow on the left pump to the right pump. (I am not draw the relief valve, filter..).All of valve in the circuit are two stage valve.

In the first circuit, I will block the port B, when combine pumps, I just supply the pilot pressure for the left position ( I must do this because I can not buy the valve 3 way, 2 position).if there is leakage at port P when the valve is in neutral,little delivery with go to tank by port T of second valve , so the pressure in the motor 2 and 3 cannot be hight, because there is loss of pressure at port P of valve 2.

In the second circuit, I use 4/3 valve as 4/2 valve, spring offset, When I need combine left pump for right pump, I supply the pilot pressure for Valve is in the center position. Because someone say that , due to construction, port T of lower stage of two stage valve cannot suffer the hight pressure, eventhought Ports T of the lower and upper stage is sepparate (is it right?) (I can not buy the valve that port P,A,B connect together) I am afraid the the seccond circuit work not proper at the hight pressure (250 bar)

- So please help me to compare which circuits is the better ?

- The second motor use to lift the boom of the crawler crane without the counterbalance valve .is it safe?

- The circuit can be work proper ?

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Power-User

Join Date: Aug 2010
Location: Wales, UK
Posts: 391
Good Answers: 18
#1

Re: Which Circuit is Better?

11/30/2010 5:08 AM

Hi Tendem,

I have not had a lot of time to look at the circuits but I do not think either of them will give you what you want.

Pump two cannot develop any pressure unless the second or the third motor is working as it has a flow path straight back to tank.

The following comments are just a list of other problems you need to consider.

Putting the flow of pump two into the tank port of the valve for the first motor will just put, pump one to one side of the motor and pump two to the other side of the motor.

The pressure you can put on the tank port of a valve can be a problem with some manufacturers and needs to be checked.

The leakage should not be a problem.

Best of luck

John

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Anonymous Poster
#2

Re: Which Circuit is Better?

12/05/2010 10:39 PM

Try Maintenance Geeks they have a lot of hydraulic information. I know the owner is awesome with hydraulics.

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