Moog Valve Operation and the Importance of Moog Filters

I don't know which type of Moog Valve you have a question about.

In general, you shouldn't have a "chocked pencil filter" if the rest of your system is functioning properly. You should be picking up any contaminant large enough to clog your pencil filter, with your main system filters. If you are collecting enough contaminant to clog the pencil filter, i would guess that you have a component failing somewhere in the system which is giving off the contamination, and should be replaced. Bypassing any filter is not a desirable practice, and measures should be taken (maintenance) to assure the filters/oil remain clean.

I suggest contacting Moog, Or a Moog distributor in your location to obtain literature, (or knowledge) of a particular valve operation. They probably have "cut-away" valve demo's, and heck maybe they have some video or something else you might find useful.

Good luck!

For anything on MOOG, you can approach Moog India (in Bangalore) since your turbines are located in India. Contact person is Mr Anil Krishnan. anil@moog.com

MOOG will be more than happy to provide your team technical seminar at your site. Believe me, it will solve all your issues pertaining to MOOG valves. They have state-of-the art laboratory to test & overhaul MOOG valves.

As you know, the Moog valve that I think you are referring to, is a servo valve. The pencil filter is to guard against small debris getting into the nozzles of the first stage. If debris do get to these nozzles, it will block one or both of them. If one is blocked, irrespective of command signals, you will get a 'hard over' fault. If both become blocked or partially blocked, you will get very erratic performance.

Rather than repeat the good advice given by others, please think about following it!

Good luck with it!

The usual scheme used with any of these aircraft type servos is to have two sections of the valve, much like a relay. If you think of the valve as having a control side (torquing coil) and main spool (operating flow) side, The control side has a solenoid that is either flowing high pressure fluid straight ahead which is the null position, or it is then through the proper electrical signal torqued to the left or right, when the fluid is torqued to the left or right the destination is to one end of the main spool and will shift the spool in that direction. A feed back spring from the main spool to the torque coil shifts the torque tube to null the signal.

The filter in the valve only filters oil on the control side of the valve, the passages are very small. If these valves aren't worn out the filters are usually the problem if there is a problem.