As a conscientious piano owner, you probably have your piano tuned regularly by a qualified technician. You may, however, notice a deterioration of its performance despite regular tuning. It's important to note that tuning is only the adjustment of the system of strings and pins that determines the pitch of each string. Your piano also requires a periodic servicing called regulation, which is the optimization of the mechanical parts of the piano to provide the best response to touch.
Regulation is the adjustment of the mechanical aspects of the pianos to compensate for the effects of wear, the compacting and settling of cloth, felt, and buckskin, as well as dimensional changes in wood and wool parts due to changes in humidity.
The three systems involved in regulation are the action, trapwork, and damper system. The action is the mechanical part of the piano that transfers the motion of the fingers on the keys to the hammers that strike the strings. It is comprised of over 9,000 parts which require adjustment to critical tolerances to be able to respond to a pianist's every command. The trapwork is the assemblage of levers, dowels, and springs that connects the pedals to the action affecting sustain and dynamics. The damper system is the mechanical part of the piano that stops the vibration of the string when you release the key and is controlled by the key and pedal systems.