Limit switches 1

[Bizzy]

are there any hydraulic "limit switches" that can cut the flow of oil to a motor when the component part has reached a certain destination and needs to be slowed down or otherwise stopped?

 

[hydromech]

Yes there are cam operated shut off valves that can close a flow off completely when required...

There are also deceleration valves that do as the name suggests. They slow a moving obeject by mechanically limiting the rate of flow to or from an actuator such as a cylinder or a motor.

Hydromech

 

[Bizzy]

Hydromech,

Can you give me any vendors/vendor products to check out
as possible hydraulic limit switches?

 

[budt]

Bizzy;

Why can't you use an electric Limit Switch?


Bud Trinkel CFPE
HYDRA-PNEU CONSULTING, INC.

http://www.fluidpower1.us

 

[Bizzy]

No electric controls permitted; it must be all hydraulic, including the limit switches; these limit switches could operate the counterbalance valves through pilot lines to regulate the flow to the motors.

 

[budt]

On these circuits I use Air (Pneumatic} Limit Valves and Air Pilot Operated Directional Controls that most hydraulic valve manufacturers offer.

Crouzet

http://www.crouzet.com/

or others offer pneumatic limit valves with many options that are available in electriv Limt Switches.


Bud Trinkel CFPE
HYDRA-PNEU CONSULTING, INC.

http://www.fluidpower1.us

 

[hydromech]

Oil Control or rather their sister company EDI-Systems manufacture quite a few different valves.

I don't know of any in the US as I am in England.

Cam operated valves are quite common so it should be quite easy to get hold of some.

Stopping the motion of something by removing the pilot will cause the object to decelerate very quickly. Counterbalance and overcentre valves are motion control valves, not flow control valves.

If you remove the pilot line to a motion control valve, it will slam shut very quickly and all of the inertia in the moving load will be taken up by the actuator and the oil inside the system, causing a huge pressure spike.

If you want to use a valve to control the pilot signal to a motion control valve, it will have to have 3 ports to allow the pilot line to drain away after the valve has closed. Otherwise the motion control valve will remain open because the pilot line is hydraulically locked.

Stopping a load using a motion control valve to stop the flow is a bad idea!

It's better to use a mechanically operated flow control valve.

If you do end up using cam operated valves, you need to make the cam as long as possible to make the load decelerate slowly and the valve must go on the line coming out of the actuator otherwise the load will carry on moving after the valve has shut.

Hope this helps...


Hydromech

 

[budt]

Look at the 4-Way Vickers valves on this page:

http://hydraulics.eaton.com/products/pdfs/682.pdf

They are only good for about 10 GPM but could be used to operate higher flow Hydraulic Pilot Operated Directional Control Valves.


Bud Trinkel CFPE
HYDRA-PNEU CONSULTING, INC.

http://www.fluidpower1.us