Mobile work machine

Mobile work machine having a chassis (10) that is designed as a tractor-trailer, a multi-axle tractor unit (12) and a multi-axle semi-trailer (14) that carries the work machine and is connected with the tractor unit by means of a fifth-wheel coupling (16), having a support construction (38) that is disposed in the region of the semi-trailer (14) and can be supported on a surface, raising the tractor-trailer, which construction has two front support booms (42′, 42″) disposed at bearing locations (48′, 48″) on the tractor unit end of the semi-trailer (14), symmetrical to the longitudinal chassis axis, which can be pivoted between a transport position and at least one support position, by means of a hydraulically driven activation mechanism, in each instance, and two rear support booms (44) that can be pivoted between a transport position and at least one support position, whereby the semi-trailer (14) has means for raising and holding the tractor unit (12) in place, wherein the activation mechanism of each front support boom (42′, 42″) has a cylinder/piston unit (54′, 54″) configured as a hydrocylinder, which extends beyond the face part (52) of the semi-trailer (14), which unit is articulated, at its one end, directly with a bearing eye (56′, 56″) that is fixed in place on the semi-trailer, and, at its other end, indirectly with the related support boom (42′, 42″), by way of a deflection gear mechanism (58′, 58″).