The pedal mechanism is the same as in the grand. The “piano” effect is obtained by pushing forward the hammer-rail (22), so that the hammers approach nearer to the strings. The “forte” pedal effect is obtained by use of the damper lifting rod (26) which is turned rearwards and forces back the whole line of damper heads so that they leave the strings.
The lost motion that occurs in the action when the “piano” pedal is used has been overcome in a most ingenious manner, and by means similar to those already described in the discussion of the grand action. The trouble to be overcome is the same, namely the lifting up of the abstract from the rocker or capstan screw caused by the forcing of the hammers towards the strings. This causes loss of touch and is very irritating to the performer.
The drawing given herewith also shows the metallic action bracket for supporting the action and the capstan screw that is used as an alternate to the key-rocker.
The lost motion attachment operates through the rod (36) which lifts the hammer rail and at the same time brings into play the compensation lever (38), which takes up the space between the abstract and the key that would otherwise intervene. Thus the touch remains true irrespective of the position of the hammer.
The materials that are required for the manufacture of the upright action do not differ from those, which we have already classified as pertaining to the grand.
The adjustment of the upright action requires that the same precautions be taken in the measurement of the key-bed, of the height of the action between the keys and striking-point of hammers, the distance of hammer from strings when at rest and so on. All these assist the action maker to adjust the alignment of the hammers and the height of the abstracts. The size of the pianoforte sometimes requires the omission of the abstracts, in which case the bottom of the wippen is felted and brought into contact with the capstan or rocker direct. All these details are attended to by the action maker when the proper measurements are given. The marking on a stick of the run of the strings is done just as was suggested for the grand scale.
In conclusion, it may be mentioned that much similarity exists between certain parts of the action of both types of instrument. It has become customary to make the length of the hammer shank and hammer butt, when fitted together, about five inches, counting from the center pin of the butt to the middle of the hammer molding. This measurement will be found correct for both grands and uprights.
The length of the hammer blow is always as nearly as possible 1 24⁄25 inches for the bass end, graduating to 1 9⁄10 scant in the treble. These dimensions should be maintained at all costs. The key lengths that we gave before are applicable to all forms of uprights. When provided with these data the action maker will be able to put out a mechanism that will fulfill the individual requirements of each kind of instrument.