A dime valve (shuttle valve), contains a small disk (the size of a dime) that moves back and fro (shuttles) inside the body of the valve according to the pressure differential. (Por eso Routledge tiene "doble efecto".)

Both shuttle valves contain a wafer-like
disk, which “shuttles“ back and forth in the valve body based on the pressure differential
created by the position of the two-way solenoid valves.
from http://www.puregas.com/files_scripts/docs/specs/PCRCO2.pdf

Here there is a forum about "shuttle disks (dime valves)".
http://talk.newagtalk.com/forums/thread-view.asp?tid=161147&...

Improper spacer was used when installing power beyond kit. If incorrect spacer is used when installing power beyond kit, load shuttle disk will not seat correctly against spacer causing leak in load sense circuit.
• Load shuttle disk (dime valve) missing between top SCV and power beyond spacer located in SCV end cover.

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Note added at 4 days (2013-09-29 11:25:03 GMT)
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http://www.arboristsite.com/chainsaw-stickies/printfriendly1...
The above link could be very useful, it includes pictures of a "dime" valve "set into the recess at the bottom of the cap"....."It has the 'dime' valve set in the mouth of the bottom of the cap like the plastic caps, but retains the valve with three screws. Much more possitive than the glue. I've had to reglue a few of the 'dime valve' plastic caps..."


I think that the "dime" amounts to no more than a simple disk with a hole in the middle (very similar to a washer, I have seen at least one case of them being referred to as 'washers for the shuttle valve' whilst researching the term).

HTH

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Note added at 4 days (2013-09-29 11:31:48 GMT)
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Maybe to give it the full descirption and distinguish from other types of "válvula selectora" I would actually go with "vávula selectora neumatica"