Disclosed is a device for use in type disc typewriters or similar machines having types carried by spokes radially extending from a common hub which is rotated to position a selected spoke at a print position. The device is operative to lock the type disc at the selected position and to restrain vibration of spokes adjacent to the spoke at the printing position. To this end there is provided a lever which acts against the hammer side of the type disc shortly before the printing of the selected type to displace the selected type spoke and interpose itself between adjacent type spokes to either side of the selected type spoke to preclude axial as well as circumferential vibration of the type disc.

A print hammer having an improved head portion for striking a selected moving print character member in a line printing device is provided. The printing device prints when the print hammer strikes a print character member at a predetermined print position forcing the character member against an ink ribbon, a print paper and a platen. The head portion is formed with an inclined surface facing the direction of approaching adjacent character members to drive an adjacent character member striking the side of the print hammer around the print hammer for avoiding jamming and damage to character members and print hammers. In a preferred embodiment the head portion is substantially "V" shaped with the apex of the V disposed in a direction opposite to the movement of the print character members.

A dot matrix printer is provided which has a row of hammer elements having horizontal impactor bars aligned at upper and lower levels and in partial overlapping relation with adjacent impactor bars. A row of print elements is also provided which alternately have horizontal upper and lower level non-overlapping impact receiving bars positioned opposite the hammer elements and in alignment with corresponding upper and lower impactor bars. Each print element has a dot print element on its opposite side and the row of print elements is mounted on a reciprocating shuttle. Means are provided for actuating the hammer elements whereby selected hammer impactor bars will impact the impact receiving bars to effect transverse deflection of the print elements to form dot impressions on a print medium.

An impact mechanism prints directly on the outer coil of a web of paper using the web itself as a backing thereby obviating the use of a separate platen. In order to hold the outer coil in a printing plane, a pair of springs continuously urge the web against a pair of stops which are adjacent to the impact mechanism. The impact mechanism includes a plurality of tines which are positioned to strike character dies against the web upon being struck by pins. The pins are distributed in a single turn helix about a cylinder which is rotatably mounted on a pivoted bracket. The cylinder rotates to index the pins across the tines and reciprocates to strike the pins against the tines. In order to sever the web into sheets after information has been recorded thereon, a pair of rollers are positioned to grip the paper being advanced from the web so that the paper may be manually brought into contact with and severed by a fixed blade.

A rotating, circular type carrier for a serial printer is equipped with axially movable type elements arranged on its periphery and having type members on one face, and a metal interposer disc with radial spokes is placed on the same axis of rotation such that the spokes line up with the other face of the elements; the inclined rear surfaces of the spokes are struck by a hammer so that the impact energy is transmitted from the hammer through a spoke to the corresponding element and the hammer is cammed back by the inclined surface of the rotating spoke.