I can't get the valve to port oil to either end of my hydraulic cylinder.

It's a new valve. I've hooked the two coils in parallel and applied +/- 50 mA (its rating). I've got terminal A hooked to terminal C and terminal B hooked to terminal D.

The plumbing is correct to the manifold that the valve mounts to - I hooked a manual hand valve to the manifold and was able to get the hydraulic actuator to move in both directions.

Seems so simple but I'm at a loss as to what to try next. Any suggestions?

 

Firstly check the valve is ported correctly.

Although 'P' is stamped for the pressure port this valve can be bolted down 180 degrees out.

Connect a 9 volt 'PP3' battery to pins A & B

Reversing the polarity of the battery should stroke the cylinder end to end.

When you disconnect the battery the cylinder should just creep off to one end, unless the 'null adjust' screw has been set to give a large bias in one direction.

This is sometimes set as a 'failsafe' but in the event of a servo valve malfunctioning it can ignore any bias setting, so don't be misled into thinking that a bias setting will ensure it fails in any particular direction.

Regards,
Robin Enderby, UK