A lot of people said the upright and grand piano's sustain pedals are the same. But the feeling of the pedal are quite different.
I tried some uprights in the showroom, the traveling length of the pedal is quite long and the force is quite continuous. On some Steinway or boesendorfer's grand pianos, the pedal traveling is very very short and stiff, almost like an on/off. It is quite hard to depress it half way.
I wonder if it is common for the pedal feeling different between upright and grand? Is the gravity causing this?
In theory the function of the sustain pedal is the same in both the grand and the vertical are the same—in practice they are not. The grand piano damper mechanism operates primarily by gravity; there are often some springs involved but they play a secondary role. When the grand damper pedal is depressed there will be an initial short distance when nothing appears to happen. This is the normal “lost motion” in the system. Then, assuming the system is regulated correctly, the dampers all start to pick up simultaneously. (This is called damper timing. If damper timing is good the dampers will all lift simultaneously, if not they will lift erratically.)
The amount of pressure your foot has to apply to the pedal reflects this; the amount of pressure needed to take up the lost motion will be relatively small but the amount of pressure needed to actually lift the dampers will be some greater. If the damper timing is adjusted precisely the amount of pressure needed to lift the dampers will increase dramatically over a very short amount of pedal travel. All of the levers involved are relatively short and stiff; there is very little bending and flexing in the system. Generally the damper lift pedal in a grand will have a mechanical stop—a piece of hard felt, and adjustment bolt, something—that limits its travel.
The upright damper system works primarily by spring action. The damper felts and barrels are very light weight components. They are held in contact with the strings by springs pressing against the damper lever. It is possible to adjust the damper mechanism so that its lifting motion is as precise as that of a grand but this is something rarely seen. More often the dampers will lift a little sooner in some parts of the compass, later in others. This spreads the increase in required pedal force over a longer distance.
In addition there is a lot more to the pedal mechanism in a vertical piano. There is a long lever reaching from the pedal to the far left-hand side of the piano. Then a long rod extending up to the damper lift rail mounted behind the damper levers. This damper lift rail is not all that rigid; it can (and does) bend some when the pedal mechanism is activated.
All of this (and more) adds up to a lot more flexibility in the overall system. This means that the pedal travel much be long enough to ensure that, even with all of the bending and twisting going on, all of the dampers lift away from the string.
Combine this with the fact that the upright damper system rarely gets the regulating and adjusting attention given to the (usually) more expensive grand and you end up with the kind of pedal “feel” described above.It should be added that a good technician can usually improve the poor pedal feel of a sloppy pedal system. It may take some considerable work time, however.
Also, the digital pianos' pedal all feel like upright's not grand's.
The digital keyboard’s “damper” pedal actuates a switch. It does not actually lift any mechanical dampers. I have no idea why it should not feel quick and precise.