I've seen a couple of the downfeed cylinder modifications online, Chuck, but
I don't recall where now (it's been at least a few years).
I think one was done with an inexpensive cylinder from Surplus Center. The
basic system is a check valve to allow free travel to lift the saw portion,
and a separate restrictor circuit (needle valve, etc) to allow the operator
to adjust the rate of descent.
I'm thinking one method was definitely done with a real hydraulic cylinder,
but one method may have been done with a pneumatic storm door closer
(although it's kinda unclear now).
I can't recall if the hydraulic version used a double-acting cylinder for
sure, but I think it was.
I think the only issue with mounting the hydraulic cylinder was to install
it in a position so it would self-bleed or stay bled so air doesn't get into
the oil side.
It seems that the hydraulic cylinder may have been mounted with one end
lower than the saw base, not in a nearly-horizontal position like the
original spring location.
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