I know the kind you are looking for, I have them on a 40 year old saw table.
There are different styles now that don't lift.
They just have a lock that keeps them in place or you can release to move.
Try Rockler.com or see the link below

http://www.rockler.com/ecom7/product...er %20locking


Charlie

"AustinScoobee" wrote in message
oups.com...
Hi everyone,
I wondered in anyone know where I might find some shop wheels I saw
once (and never again!) They are about 2" diameter, but the neat
feature of these is that they have a pedal which raises and lowers
them, so that when attached to a large bench or workstation, you can
drop them to stay in place, then use the pedal to raise them and move
the whole station..

I hope I have explained this well enough..I've done exaustive searches
on the net, and never seen one again..

Any help appreciated
Cheers
G