The mounting means comprise: on the straddle carrier side, a main frame (1) mounted on wheels (5, 6) and suitable for selective lifting and lowering of the main frame in relation to the ground (10) on the equipment side (14), an auxiliary frame (13) suitable for fixing to the main frame (1) using detachable connection means allowing it to be detached and of a number of struts (49, 51) for supporting the auxiliary frame on the ground when the auxiliary frame is separated from the main frame. The main frame and the auxiliary frame both comprise a pair of parallel, substantially horizontal girders (2 or 17) One of the frames comprises means for longitudinal guidance (17) able to co-operate with the girders (2) on the other frame to guide the two frames in along each other, when the main frame (1) moves longitudinally with respect to the auxiliary frame (13) supported by the struts (49, 51) At least one of the frames includes a stop member (36, 37) able to co-operate with the other frame to limit the distance of longitudinal displacement of the main frame (1) towards the auxiliary frame (13) and to define a stop position that allows the two frames to be assembled and affixed using said means of connection.Ce système de montage, qui comporte, du côté chariot enjambeur, un châssis principal (1) monté sur roues (5, 6) pouvant se relever du sol et sabaisser, de manière sélective, comporte également, du côté équipement (14), un cadre auxiliaire (13) pouvant se fixer au cadre principal (1) à laide de dispositifs de raccordement détachables ainsi quun certain nombre détais (49, 51) soutenant le cadre auxiliaire sur le sol lorsque celui-ci est séparé du cadre principal. Ces deux cadres comportent, tous deux, une paire de poutres parallèles, quasiment horizontales (2 ou 17). Lun des cadres comporte des mécanismes de guidage longitudinal (17) coopérant avec les poutres (2) placées sur lautre afin de les guider tous le deux et ce, lorsque le cadre principal (1) se déplace longitud
