This article is from the Piano Purchase and Maintenance FAQ, by Isako Hoshino firstname.lastname@example.org with numerous contributions by others.
Pianos are HEAVY. A small upright can easily weigh as much
as 400 lbs. Also, many of the older uprights are extremely
top-heavy (All the weight of the plate, action, and pinblock
are at the top of the piano, making it unstable when it is
moved on its casters). If you do need to maneuver more than
few steps of stairs, it is highly recommended that you use a
professional piano mover. However, if you still choose to
move the piano yourself, you will need a few people to help
you move the piano. It may not be such a bad idea to get a
back brace to protect yourself from over-straining.
Following are some tips to aid you, directed for upright,
console, spinet piano moving (you probably don't want to move
a grand piano yourself):
(1) You will need thick wrapping blankets to protect your
piano from being scratched. Don't use the thin blankets
usually supplied by U-Haul and other rental agents. Use
a lot of those plastic packaging tapes to secure the
blanket around the piano (don't tape the blanket onto
the piano... That may damage the finish. Just wrap the
blanket, and "mummify" it with the tape)
(2) If you chose not to carry the piano, you will need a big
cart (a heavy-weight flatbed with big casters on the
bottom) since the casters on the pianos are not made to
move it across the floor or on irregular ground, but
only to position it after it was moved close to its
final resting location.
(3) Get hold of a large, (preferably covered, but not a
necessity to move it just across town) truck or trailer.
(4) Once you get the piano in the truck, place some 2x4 or
4x4 wood planks under the piano, from back
to the front (parallel to the sides, perpendicular to
the front and back surfaces), lifting it off its
casters. Place a few to distribute the weight. This
will help stabilize the piano on the floor, and also
alleviate any strain to the casters caused by the
irregular floor of trucks. It also will help reducing
the "rolling-off" accidents.
(5) After you check that the piano is stable on the
wooden planks, secure it against the wall with
*moving straps*, not ropes. Moving straps
are usually thick, 1-2 inch wide nylon/acrylic tape,
and is much stronger than a rope, and doesn't stretch
out of place as much when the truck gets bumped around
over the potholes.
Above all, BE CAREFUL. You can easily hurt yourself if you
strain too much, and it's better to be over-kill in
protecting and securing the piano (the alternative can lead
to disasters... like a flying piano off or through the truck
cargo...) and having extra pairs of hands available.