Herein disclosed is a printing device for printing bar codes, or the like. The printing device includes a printing head which is adapted to be received in the body of the printing device for printing and which can be removed for selecting the bar codes to be printed. The printing head includes a plurality of bar code type rings axially aligned with one another such that they can be manually separated axially so that they can rotate independently of one another for selecting the bar code to be printed. The bar code type rings are moved together for printing. Separation of the type rings causes a stopper to protrude out of the casing of the printing head to engage the frame of the printing device in such a manner as to prevent substantial movement of the printing head, such movement being a necessary part of the printing operation. Bringing the type rings together to their printing position retracts the stopper, which permits printing movement of the printing head.

A value setting mechanism constituting an interface between printing mechanism and an electronic accounting system in a franking machine has each value precisely set without possibility of alteration during a printing cycle. A four digit value can be set by rotating thumb wheels that transmit the value to encoding switches and printing elements. A spring loaded locking bar lies between aligned recesses on the wheels when properly set. To initiate a cycle a trip lever is electromagnetically moved from a first position to a second position releasing a clutch pawl to actuate the printing elements via a clutch and to close switches. If bar fails to enter aligned recesses, a detent unit prevents the trip lever from moving to the second position. When it does so move, an arm thereon inhibits detent unit from moving in a direction to allow bar to withdraw from the aligned recesses.

A printing control system includes a printing mechanism having settable print members. A gear is rotatably mounted and operably connected for selectively setting the print members. The gear is connected to control inhibiting the printing mechanism from being energized to print. The gear may also be connected to control inhibiting the selective setting of the print members.

A printing machine is provided for imprinting forms with fixed data from embossed printing plates and variable data from manually settable print wheels by moving a roller platen from a start position across the printing elements and the form to an actuated position to perform a printing operation and back to the start position to complete a printing cycle. The print wheels are selectively positionable by keyset levers movable from a zero position to a selected printing position for rotating each of the print wheels to a desired peripheral setting. Reset means is provided for restoring each of the keyset levers from the selected printing position to the zero position in response to movement of the roller platen through a printing operation, and lock-out means is provided to inhibit movement of the roller platen through a printing operation following a printing cycle. The roller platen is unlocked for movement in response to movement of at least one of the keyset levers from the zero position to a new setting.