Hammer device for printer

In a serial printer having a type wheel which is provided with a multiplicity of radially arranged fingers each carrying at least one type on a front face thereof and a fount detent on a back which is positioned coaxially with the type, a hammer device comprising:

• (a) a support member mounted on a frame of a carriage;
• (b) an impacting means movably mounted on said support member for translation between a first position where it is clear of a fount detent and a second position where it is engaged with the fount detent at one end thereof;
• (c) guide means with which the impacting means are slidably engaged to be thereby guided during translation between the first and second positions;
• (d) drive means for driving the impacting means from the first position to the second position;
• (e) a tension spring for constantly biasing the impacting means toward the first position;
• and
• (f) positioning means for accurately positioning the impacting means in predetermined vertical and transverse orientations;
• the guide means for guiding the translation of the impacting means comprising at least two rotary bearings each with a flange which constitute a reference side for the translation of the impacting means and at least one rotary bearing with a flange which defines the other side for the translation;
• the positioning means comprising a first plate fixed in place on the support member and a second plate fixed in a place adjustable transversely toward and away from said first plate, said first plate carrying the two rotary bearings at the reference side thereon and said second plate the single rotary bearing so as to cooperate with the flanges of the rotary bearings.