Standard piano casters are only meant for occasional small movements, such as rolling the piano a few feet on a smooth floor Pianos moved often, such as those on stages, in school buildings or in churches, must be mounted on special dollies to prevent damage to the original casters and legs.
To safely move your home piano to a new spot in the room, here are some tips:
If the piano is sitting on carpeting, or if the floor has any obstacles like thresholds, furnace grates, etc., you need to be very careful to avoid straining the legs. First lower the lid! Then position three people around the piano, one near each leg. (Remove belt buckles, rings, etc. that could scratch the piano's finish.) It's not necessary to lift the piano off the floor, but just to take some weight off the casters so they will roll more easily. Move the piano slowly, a few inches at a time. Caution: Never roll a caster over any bump in the floor; always lift it over, one leg at a time, using extra help.
The same cautions for grands apply here. Use two people, one at each end of the piano (two at each end for large uprights), and always lift the casters over bumps in the floor. Caution: Beware that most of the weight is located toward the back of an upright piano, making it prone to tipping over if leaned too far back. When moving an upright out from a wall, never allow anyone, especially children, to stand behind the piano.
Most spinet and console pianos have thin, unsupported front legs. These take extra care, since they can easily break off if caught in a crack or dragged across soft carpeting. To avoid damage, carefully tip the piano back slightly as you roll it to reduce weight on the front legs.