A special-purpose clutch incorporated in a drive mechanism of hot stamping apparatus wherein heated type on a rotary type carrier is periodically pressed against a printing ribbon in superposition on a continuous strip of plastics or other material being fed at constant speed over a platen, thereby imprinting characters on the strip at constant spacings. The clutch comprises a drive disk mounted on a motor output shaft, a driven disk mounted on a type carrier shaft, and a spring through which rotation is normally imparted from the drive to driven disk. The spring is yieldable to permit the driven disk to be rotated, while the heated type is being pressed each time against the printing ribbon, by the strip of material at lower speed than the drive disk. The angular speed of the type being pressed against the ribbon can thus be precisely synchronized with the linear speed of the strip traveling over the platen.

A printing apparatus in which a comma printing mechanism prints commas at any desired location within a printed number. Comma printing is accomplished by comma hammers, with one hammer provided between each two numerical places of the printing apparatus. All the comma hammers are initially maintained in a nonprinting position, and all are moved to an intermediate position prior to the printing of a number. Selected comma hammers, corresponding to the locations within a number at which comma printing is desired, are then advanced to a printing position, and the number is printed. After the number and selected commas are printed, the comma hammers are returned to the initial nonprinting position.

A mechanism for actuating a platen of a printer in which a cooperating pin and lever are provided to permit a plurality of printing rings with the desired characters thereon to be printed to be placed into a printing position, to move a platen into abutting engagement with the printing rings and hold them engaged for printing, all during a first period of time, and to remove the platen from the printing rings during a second period of time, and in which the first time period is about two to three times longer than the second time period so that the speed of the printer for each printing operation is increased.

A printing unit particularly intended for price labelling machines, comprising annular printing wheels supporting matrices at their outer periphery and equidistantly spaced notches at their inner periphery into which notches engages a rod to advance the wheels to forward the desired matrix to printing position. The printing pressure is obtained by an impact rod striking a shoulder formed on a pressure arm, the movement of which is transferred to the associated printing wheel forcing the intended matrix thereon against the place of printing. As the printing wheel is stationary during the printing operation the resulting print is sharp and clear.

An improved printer comprising a plurality of character rings provided with a plurality of characters on the respective peripheries thereof and corresponding pluralities of ratchet wheels and pawls. Each ratchet wheel is radially mounted on a character ring and a corresponding pawl is oscillatably mounted for engaging its corresponding ratchet at a preselected interval for stopping its associated character ring when a selected character is located at a predetermined position. Guides are provided for determining the constancy of oscillation of the pawls. Each pawl is spring driven into engagement with a corresponding ratchet wheel and a normal bias toward a corresponding ratchet wheel is provided. A releasable restraint acts oppositely to the bias on the pawl for normally preventing the pawl from engaging with its corresponding ratchet wheel. An electromagnetic device is provided for transducing an electronic signal into a mechanical motion which releases the restraint on the pawl whereby the bias on the pawl drives the pawl into engagement with its corresponding ratchet wheel and the character ring associated therewith is thereby fixed for aligning a preselected character in the strike path of an actuable platen. At a print command the platen abuts the character in its path and a paper or like imprint receiver is provided with an imprint of the preselected character.