PLATE HOIST ?'s

[McNeilTom@aol.com]

I've seen an engine hoist used, and it seems fairly OK.

I've also used block and tackle.  A drawback is that it's awkward to hoist,
guide the plate, then belay the rope singlehandedly, as I usually work.

I've also used an electrically powered steel-cable winch.  This I don't
recommend.  For one thing, it's pretty expensive.  But the worst is that even
though it had extreme gear reduction (hence the expense), it starts and stops
with a jerk and has only one speed (too fast sometimes, but too slow other
times).

The best system I've used, and still do, is a thing called a differential
chain hoist.  This is not the thing often seen in farmers' sheds, with one
light loop of chain driving a gear-reduction transmission to a sprocket that
operates the heavier lifting chain.  (Bear with me now as I try to describe
the thing!)  It has an upper block with a double chain-wheel, one of which
has one more sprocket tooth than the other.  These two wheels are one
casting, and I believe this sort of thing is actually called a 'gypsy'
instead of a sprocket.  It uses a chain that looks about like ordinary
welded-link chain, but the links are shorter, more nearly round.  Anyway,
imagine about 20 feet of 1/4 inch chain made into a permanent loop; double
that into two loops, and hang one on each of the two wheels of the upper
block.  Hang a single-wheel block (doesn't need the "teeth" of a gypsy) on
one of the loops; this will be the load-bearing loop.  The loop without a
lower block is then the operating loop.  When you pull the chain in the
hoisting direction, the upper block gives you slightly more chain in the
operating loop, while it slightly shortens the load-bearing loop, lifting the
load.  This is because the two wheels (actually one double-wheel) have
unequal numbers of teeth.

The one I have has 14:1 ratio, and is rated at a half-ton (1000 lbs), enough
to lift an entire concert grand.  If it were perfectly efficient
mechanically, it would take 70+ lbs pull to accomplish this; of course there
is some inefficiency due to friction; I estimate it takes about 90 lbs. of
pull to lift 1,000 lbs.  I have done this quite a few times, not too hard for
a 200 lb. guy.  And of course smaller pianos, or just the plate, are much
easier.
A wonderful thing about this differential chain hoist is that you can go as
slow as you want or as fast as you need, and you can stop at any time and the
load just hangs there - no belaying required, no ratchets to slip.  Very
fool-proof and safe, and wonderfully simple.  Low maintenance, too: a shot of
grease to two zerks once every few years.

I'll try to discover the manufacturer of mine if anyone's interested.  I
would guess it might cost about $100 in today's money.

Why did I lift so many concert grands?  Well, when I was at SUNY Fredonia, we
had a recital hall the stage of which was an island, exactly 36 inches above
the floor of the rest of the building.  No handicapper ramp, no elevator, and
four cute little stairways arranged to exclude any piano.  We had two S&S Ds
that lived there, plus a French double harpsichord, and a gargantuan
iron-plated Sabathil double harpsichord all of ten feet long.  Mostly, these
all stayed put, except the French harpsichord which is easy to move anyway.
 Twice, however, we had to move all the instrument off the stage for
architectural renovations (and later return them).  And there were occasional
changes of instruments for maintenance.  I rigged a stout chain to a steel
girder in the attic, some 45 feet above the stage deck, and exactly over the
edge of the stage.  I installed a short piece of pipe through the ceiling so
I could drop the long chain through without loosening too much of the
asbestos ceiling material(!).  Then I lifted the instruments, either standing
on their own legs, or on a moving board, depending on where they were headed.
 I enlisted the help of two or three warm bodies to help sway the load away
from the edge of the stage in whichever direction was necessary.  Probably
none of you will have to use this technique (I hope!), but it was the answer
to a persistent problem for us.

- Tom McNeil -
Vermont Piano Restorations