Self-propelled construction machine, in particular a road milling machine, stabiliser, recycler or surface miner, which has a machine frame, a work roller arranged on the machine frame, and a left-hand edge protector arranged on the left-hand side of the work roller in the working direction and a right-hand edge protector arranged on the right-hand side of the work roller in the working direction, a hydraulic system for raising and/or lowering the left-hand and right-hand edge protectors (5A, 5B) being provided, which system has a hydraulic source for providing hydraulic fluid, the hydraulic system being designed such that the hydraulic source can be brought into fluid connection with one of the two cylinder chambers (6AC, 6AD) of a first double-acting hydraulic cylinder in order to raise and/or lower the left-hand edge protector and with one of the two cylinder chambers (6BC, 6BD) of a second double-acting hydraulic cylinder in order to raise and/or lower the right-hand edge protector such that the left-hand and/or right-hand edge protector (5A, 5B) can be raised and/or lowered, characterised in that the hydraulic system has a first auxiliary direction control valve (14, 29, 34) which is associated with the first hydraulic cylinder and has two switch positions, a second auxiliary directional control valve (15, 30, 35) which is associated with the second hydraulic cylinder and has two switch positions, and only a single main directional control valve which is associated with the first and second hydraulic cylinders (6A, 6B) and has three switch positions, and the hydraulic system is designed such that, in a first switch position of the main directional control valve and in one of the two switch positions of the first and second auxiliary directional control valves (14, 15; 29, 30; 34, 35), one of the two cylinder chambers of the two hydraulic cylinders (6A, 6B) can be supplied with hydraulic fluid, and, in a second switch position of the main directional control valve and in one of the two switch positions of the first and second auxiliary directional control valves (14, 15; 29, 30; 34, 35), the other of the two cylinder chambers of the two hydraulic cylinders (6A, 6B) can be supplied with hydraulic fluid, such that the left-hand and/or right-hand edge protector (5A, 5B) can be raised or lowered, and, in a third switch position of the main directional control valve and in one of the two switch positions of the first and second auxiliary directional control valves (14, 15; 29, 30; 34, 35), a fluid connection between the two cylinder chambers of the first hydraulic cylinder and a fluid connection between the two cylinder chambers of the second hydraulic cylinder can be established such that the left-hand and right-hand edge protectors (5A, 5B) can assume a floating position. characterised in that the hydraulic system has a first auxiliary direction control valve (14, 29, 34) which is associated with the first hydraulic cylinder and has two switch positions, a second auxiliary directional control valve (15, 30, 35) which is associated with the second hydraulic cylinder and has two switch positions, and only a single main directional control valve which is associated with the first and second hydraulic cylinders (6A, 6B) and has three switch positions, and the hydraulic system is designed such that, in a first switch position of the main directional control valve and in one of the two switch positions of the first and second auxiliary directional control valves (14, 15; 29, 30; 34, 35), one of the two cylinder chambers of the two hydraulic cylinders (6A, 6B) can be supplied with hydraulic fluid, and, in a second switch position of the main directional control valve and in one of the two switch positions of the first and second auxiliary directional control valves (14, 15; 29, 30; 34, 35), the other of the two cylinder chambers of the two hydraulic cylinders (6A, 6B) can be supplied with hydraulic fluid, such that the left-hand and/or right-hand edge protector (5A, 5B) can be raised or lowered, and, in a third switch position of the main directional control valve and in one of the two switch positions of the first and second auxiliary directional control valves (14, 15; 29, 30; 34, 35), a fluid connection between the two cylinder chambers of the first hydraulic cylinder and a fluid connection between the two cylinder chambers of the second hydraulic cylinder can be established such that the left-hand and right-hand edge protectors (5A, 5B) can assume a floating position.