Off-set printing apparatus

Printing apparatus comprising a carrier plate having a pair of spaced parallel racks extending in a printing direction and also having a flat printing plate support and a flat printing carrier support located behind the printing plate support in said printing direction, both of which supports are located between said two racks, a printing roller cooperable with said carrier plate and freely removable therefrom, said printing roller being covered with a rubber blanket and having a pinion on each of its ends for engagement with an associated one of said racks, said printing roller having hand grips at its opposite ends and being freely rotatable relative to said hand grips, a centering bar extending perpendicular to said printing direction and located on said carrier plate at the front of said printing plate support in said printing direction, said printing roller having a centering groove complementary to said centering bar extending parallel to its axis which engages said centering bar at the starting position of said printing roller, said centering bar being removable from said carrier plate and fastenable to said carrier plate by means of at least two pins which are insertable through complementary holes in a printing plate to hold such printing plate on said printing plate support in a fixed position relative to said printing plate support, a clamping bar on said carrier plate located between said printing plate support and said printing carrier support and oriented perpendicular to said printing direction for fixedly holding a printing carrier to said printing carrier support, said clamping bar being supported on said carrier plate for pivotal movement about an axis extending perpendicular to said printing direction between a clamping position and releasing position with respect to a printing carrier supported on said printing carrier support, means biasing said clamping bar toward said clamping position, said clamping bar having an upper portion which extends upwardly beyond said printing carrier support, the spacing of said clamping bar as measured in the printing direction from said centering bar being equal to the circumference of said printing roller and the width of said upper portion of said clamping bar as measured in said printing direction being smaller than the width of said centering groove in said printing roller so that as said printing roller moves over said clamping bar said upper portion of said clamping bar is freely received in said centering groove without interfering with the movement of said roller in said printing direction, said clamping bar being engageable with one end of a printing carrier received on said printing carrier support to position such printing carrier relative to said printing carrier support in the direction parallel to said printing direction, and a stop on said carrier plate in the form of an upwardly extending projection located along one side edge of said printing carrier support, said projection being engageable with a side edge of a printing carrier received on said printing carrier support to position such printing carrier relative to said printing carrier support in the direction perpendicular to said printing direction.