The Parts of a Grand Piano Action

Like the vertical piano action, the grand piano action has a framework of cast-iron or die cast action brackets, and several hardwood or aluminum rails. 

Two screws hold each grand piano action bracket to the key frame so the action, keys, and key frame all come out of the piano in one piece. The Steinway tubular metallic action has wooden rails encased in extruded metal tubing soldered to the brackets.
Some parts of the grand piano action have the same names as their counterparts in the vertical piano action, including the keys, capstans, wippens, jacks, hammer shanks, hammers, backchecks, dampers.

As in an upright, the key pushes on the wippen, the wippen on the jack, and the jack on the hammer.
From here on, the resemblance ends, because the grand piano action has an additional assembly on each wippen called the repetition lever.
This lever enables the grand piano action to repeat notes faster than the vertical can.