for the lifting and lowering of the boom 86 here the hydraulic cylinder 26 is connected in joint free to pivot to a first and a second bearing location 88 90 where the rod end side 92 is connected in joints to a second bearing location 90 on the boom 86 and the piston end 94 is connected in joints to the first bearing location 88 on the housing 84 furthermore the hydraulic reservoir 20 the pump 18 as well as the controller 12 are positioned at or in the housing 84 and are connected to each other by hydraulic lines 14 16 96 furthermore the supply lines 22 24 between the controller 12 and the hydraulic cylinder 26 are shown in fig2 the automatic shut off valve 34 as well as the control valve 52 are located in a common valve building block directly at the hydraulic cylinder 26 the hydraulic accumulator 48 is preferably also arranged at the hydraulic cylinder 26 so that the hydraulic line 46 between the common valve building block and the hydraulic accumulator 48 can be configured as a rigid connection that does not require a separate automatic shut off valve control or switching signals are generated over a control arrangement not shown with which the controller 12 as well as the control valve 52 are controlled or switched see fig1 corresponding to the switch positions described above the hydraulic cylinder 26 can be actuated in such a way that the boom 86 can be raised retained in a fixed position lowered or retained with.