2 Directional Valve Tandem Type is in Series?

This guy's already asked the same question: Replace Directional Valve Type Tandem by Type Float

Oh, never mind, it was you.

For your 1st question you already have the answer

How do you want to use the motors one at a time ? both together ? both same direction or in different directions ?

Give MORE input about the function you want to perform and then you will get correct answers!

Describe EXACTLY what you want to achieve !

Thank for your reply.

the first and the second motor should operate separate,not the same time , It is not much important.

But , Both of motor must be operate in 2 direction, they operate both same and different direction due to control of operator.

thanks, thanks, thanks

There may be more than one way to do this, but I would go for two open-center valves assembled as a block manifold. Pump pressure to P of first valve, T of first valve to P of second, T of second back to tank (through a filter). A and B of first valve to ports on first motor, A and B of second valve to ports on second motor.

If you try to operate both motors at once, the pressure will divide between the two motors. If the pump does not produce enough pressure for this, they will stall. But if the motors are sized to operate at pressure P and the pump can produce 2P, then it will work. The first valve and motor will need to handle pressure 2P in this case.

Suitable components should be readily available.

The first "T" will be loaded by the pressure of the second motor. But "T" does NOT accept high pressures so that the first valve will burst! Unfortunately it will not work properly if pressures are > ≈5 bar ( in some cases 10 bar).

There are a couple of conditions to be fulfilled at same time :

- when valves not actuated (in neutral position) pump should deliver at lowest possible pressure in order to save energy.

- valves should work independently

- if load can become active the motor+valve should not let it come back or go further

to mention only some of them.

The most usual valves type 4/3 have above center configurations.

Config "A" does NOT block the actuators when valve in neutral so the load can move free if other valves (piloted check valves) are not provided. Pump is in neutral blocked so that it works at the pressure relief valve (the highest value which should be reached only in limit case).

Config "B" allows a pump flow to tank in neutral position and thus reduces considerably energy waste and blocks the actuator in the position it was left (if the internal leak is neglected i.e. if the stop is not too long).

Config "C" has the advantage of "B" with respect to the actuator blocking but the disadvantage of the "A" version with respect to pump pressure.

The "1/2/3" ways to build the controls for 2 motors show what is good and what is bad in each one:

1- Actuator "free" and pump at high pressure in neutral NOT good

2- NOT possible to ,use only a motor since pressure line is short circuited to tank by the other valve so that also NOT good.

3- Actuator blocked but pump at highest pressure so that also NOT good.

The variant "4" shows a way to solve the problem (there is an other but I let you find it): the valves are 6/3 and in neutral the pump is connected to the tank thus low pressure losses! OK one constrain is solved! What happens if a valve is actuated ? the above mentioned connection is interrupted (being is series which ever valve is moved the interruption will occur) so that the pump will supply the oil to the required pressure to move the load. When the valve comes back to neutral the motor is blocked and the pump is again unloaded! Great, this way we solve both problems!

Now there is a last one when yo act BOTH valves and the loads are different so that one motor can move at a lower pressure than the second. What will happen ? The low load will move but the high load will not move till the load on the first motor will reach a level equal to the load on the other so that the second load will start to move as well. This problem is always present in parallel work with actuators at different pressure levels.

This can be solved as well but it is NOT in your question so that I stop my explanations here and hope that your home work will be accepted even if it is not complete.

Nick

I am pretty sure that plenty of hydraulic valves are made in which port T can handle the full pressure of any of the others. Several valves of schematic "B" (open center) can be ganged into a single block manifold. If all the valves are in center position (free flow), the pump builds only enough pressure to equalize piping losses (and filter pressure drop, if any).

Which manufactured single stage valve is able to accept nominal 300bar (test pressure 1.5*nominal) on port T ? I am not aware and would appreciate to get the information.

Thanks in advance.

Nick

You are so kind for me, Nick name, The first, i would like to say thanks you very much (my english is not good, so, it is difficult to say exactly how much i thanks you). The question i ask is not the home work. It is my work in my company. I read the information on "Vicker Industrial hydraulic manual" say that " the tandem type has cylender ports block in neutral but the pressure port open to the tank permitting two or more valve to be connect in series or "tandem"" . And i check my tandem Valve two stage, i recognize the the port "T" of upper stage (electrical control, pilot operate) is separate from the port "T" of lower stage.And port "T" is seem not be difference from port "P".So please explane for me where"the burst" will happen.

the valve is tested so it is dirty.

Thank you very my much. i am affraid that i get the mistake, the valve will be brust. So, please tell me more. thanks

You are so kind for me, Nick name, The first, i would like to say thanks you very much (my english is not good, so, it is difficult to say exactly how much i thanks you). The question i ask is not the home work. It is my work in my company. I read the information on "Vicker Industrial hydraulic manual" say that " the tandem type has cylender ports block in neutral but the pressure port open to the tank permitting two or more valve to be connect in series or "tandem"" . And i check my tandem Valve two stage, i recognize the the port "T" of upper stage (electrical control, pilot operate) is separate from the port "T" of lower stage.And port "T" is seem not be difference from port "P".So please explane for me where"the burst" will happen.

Mothod 4 is the best , but, the valve 3/6 is not easy to buy in my country. so....

Thanks you very much

Good day sir

this is the circuit of system

I am afraid the the valve is "burst" as you said, i check that the port "P" just only connect to port "T". I think i can use the port "T" as port "P". SO Why the valve is "burst". and where the valve will burst/ Please help me. Thansk you very much.