opened by the tappet 47 via the tappet spring 48 therefore the pressure in the chamber c is relieved in that more fluid escapes via the control valve 95 as can enter via a throttle 97 since the control valve 96 remains closed the spindle s is pressed towards the opposite end position by the inflow of hydraulic fluid in the chamber d via a throttle 98 moving the spindle towards the chamber c closes the operating valves 91 and 94 while the operating valves 92 and 93 open causing the piston rod 33 to move into the opposite direction therefore in each of the respective end positions of the piston rod 33 the opening of the control valves 95 and 96 causes automatic reversal the driving cylinder operates otherwise via control by the valves the control valves 95 and 96 open as the springs 48 or 57 respectively are compressed the pressure within the valves decreases during the initial path of travel of the tappets 47 52 which upon reversing cause the valves 95 96 to close again as a result the movements of the spindle are initiated instantly but are not sudden in spite of the high pressures exerted by the hydraulic fluid fig8 to 10 show an applied embodiment of a control the action sequency of which has been described with the aid of fig4.