In message , J Lynch
writes
A "tripcock tester" only tests that there is a tripcock arm present and
in correct alignment (at which point the tripcock tester light goes
out). It does NOT check that the tripcock will stop the train if
activated, the assumption being that if it is in the right place and
alignment that it will do the job it is provided for, if required.
I appreciate that, it's a pity that tripcocks no longer dump the
trainline to atmosphere as they used to, at least that was fool proof.
--
Clive