Abstract: A chassis (11) for mounting component units (17, 19) of an electric switch cabinet for elevators and escalators, comprising at least one shaped part (15) serving as main supporting member, said shaped part being composed with a plastics material of lasting resetting force with respect to compression and being provided with at least one receiving recess (29, 31) for receiving a component unit (17) of a first type in substantially form-locking manner, and comprising at least one mounting rail (21) serving as auxiliary supporting member and anchored in the shaped part (15), said mounting rail (21), at least over a predetermined partial length thereof, being accessible in a free space (42) of the shaped part (15) for mounting at least one component unit (19) of a second type to said mounting rail (21), with said free space (42) being designed to selectively receive component units of the second type in different numbers, shapes and sizes.