Repeat spacing mechanism for typewriters

Claim 1

A repeat spacing mechanism for typewriters having a frame, a carriage mounted on said frame and movable in a letter feed direction and in the opposite direction thereto, and a carriage urging member for urging said carriage in the letter feed direction, comprising: a base board fixed to said frame, a wheel shaft pivotally mounted on said base board and operatively connected with said carriage so as to be urged to rotate by an urging force of said carriage urging member, a first wheel and a second wheel coaxially supported on said wheel shaft and each having a plurality of teeth on the periphery, a pawl shaft mounted on said base board in parallel relation to said wheel shaft; a first pawl and a second pawl normally registered with said first wheel for causing a single step movement of the carriage in the letter feed direction and rockably mounted on said pawl shaft to alternately engage said teeth of the first wheel and disengage therefrom, a first spring for urging said second pawl to be rocked about said pawl shaft in one direction in which said second pawl is disengaged from said first wheel, stop means mounted on said base board for normally maintaining said second pawl against the urging force of said first spring in a normal position in which said second pawl is disengaged from the teeth of the first wheel, a second spring for urging said first pawl to be rocked in said one direction about said pawl shaft so as to cause said first pawl to be normally engaged with the teeth of the first wheel, connecting means for connecting said second pawl with said first pawl for rocking the first pawl together with the second pawl in the direction opposite to said one direction so that said first pawl is disengaged from said first wheel after said second pawl is engaged with said first wheel, limiting means for determining the broadest angle of separation between the first and second pawls, said limiting means being provided on at least one of said first and second pawls, an actuating member operatively connected with said frame for moving said first and second wheels relatively to said first and second pawls in the axial direction of the wheel shaft to cause said second wheel to be registered with said first and second pawls when said actuating member is operated, manual operating means operatively connected with said frame and associated with said actuating member for operating said actuating member, and cam surfaces provided on those portions of the teeth of said second wheel which engages said first and second pawls, each of said cam surfaces being formed to conduct a cam action between said second pawl and the cam surface engaged therewith as well as between said first pawl and the cam surface engaged therewith by said urging force of said carriage urging member for causing said first and second pawls to be cyclically engaged with and disengaged from said second wheel during operation of said actuating member; whereby said first and second pawls rock repeatedly while said wheel shaft rotates under the urging of said carriage urging member in said letter feed direction to cause said carriage to make a repeat spacing movement in the letter feed direction during operation of said manual operating means.