4 1 and 4 2 which are adapted to the keel shape in the preferred form grooves 4 1 and 4 2 are v shaped and edges 5 2 and 6 2 are wedge shaped so as to form a positive and precise engagement of the parts the rear support plate 2 of bank support 1 consists of two sections a straight vertical wall 2 1 and an upper horizontal extension or bar 2 2 which extends inwardly the latter extension or bar 2 2 is also provided with vertical sectional grooves 2 2 1 and 2 2 2 for accommodating the individual print ram units 5 and 6 the sectional grooves 2 2 1 and 2 2 2 serve to accommodate a flexure member such as a cylindrical resilient pin 19 extending between the v shaped grooves 9 1 1 and 9 2 1 of the lower and upper unit frame extensions 9 1 and 9 2 the latter grooves are vertically aligned with each other in the assembled state the vertical supports 4 and 2 of bank support 1 are connected to base 3 this connection can be detachable using such means as screws or snap joints or the like for adjacent unit frames the sectional grooves in the vertical supports of bank support 1 have different depths so that only all even or odd unit frames are aligned with each other this stagger alignment prevents adjacent print ram units from noticeably for example magnetically interacting with each other during operation from fig2 showing a simplified lateral view looking in the direction of arrow p fig1 of the bank with the print ram unit 6 it may be seen in particular how.