Hydraulic circuit, a real brain teaser - please help

[bwbama]

This is a hydraulic circuit design problem. I need some ideas on controlling a hydraulic cylinder with two separate manual valves. The cylinder must be controlled by either of two people (in different locations) using manually operated 3-position, 4-way directional valves. The valves cannot be spring-centered. Even if one operator has left his valve in the A or B position, then I would like the other operator to be able to shift the cylinder in the other direction. Any ideas?

 

[budt]

The only simple way would be to feed a 6 ported selector valve from the two 4-way directional valves that would have to be positioned hydraulically or electrically from the two operator stations. This would leave the operator who could be holding a signal to the 6 ported selector in control until they let up.

If you are not familiar with a 6 ported selector valve they are made by several Mobile valve companies like Gresen and Cross and are often found on backhoes so one directional control can do two functions like raise and lower outriggers and/or move the bucket. Since these functions would not be operating at the same time it saves an extra valve in the bank. Bud Trinkel
Certified Fluid Power Engineer
HYDRA-PNEU CONSULTING, INC.
812-853-32344
fluidpower1@hotmail.com