936,478. Propelling rail vehicles. KEMA KOLN - EHRENFELDER MASCHINENBAU - ANSTALT G.m.b.H. March 9, 1960 [June 11, 1959], No. 8368/60. Class 104 (2). In a vehicle moving device having a cylinder assembly which is hydraulically operable in an alternating fashion and associated therewith an auxiliary control member 10 dependent on the positioning of one or more pistons 3, 3a for the indirect reversal of a main control piston slide valve 15, 30 incorporated between a pump 17 and the working cylinders 2, 2a and reservoir 16 in the hydraulic system, the control conduits 11, 13 and 14 lead through the auxiliary control member 10 to the main control slide valve 15, 30 and are capable of being exhausted independently of the operating medium delivered from the pump 17 to the working cylinders 2, 2a and the main control slide valve 15, 30 has associated therewith reversing chambers 35, 36 for automatically setting the main control slide valve 15, 30 into a mean position so that with the control conduits 11, 13 and 14 exhausted the main control valve forms a means located in the conduits 11, 13 and 14 for admitting the operating medium to the working cylinders 2, 2a in order to arrest movement of the cylinder assembly. In the arrangement shown in Fig. 2, vehicles are propelled by catches 7, 7a, pivotally mounted on slides 6, 6a, alternatively reciprocated in guides 5 through rods 4, 4a by pistons 3, 3a movable in working cylinders 2, 2a. The slides 6, 6a are interconnected through racks 8, 8a and a pinion 9. The cylinders 2, 2a are fed with hydraulic fluid from a reservoir 16 by a pump 17 through a main control valve 15, 30 and conduits 23, 24. A changeover element 43 actuated by the pistons 2, 2a affects reversing movement of a piston valve of the auxiliary control element 10 which in turn determines which of the conduits 13, 14 are fed with compressed air from a conduit 11 to move a piston 30 within the housing 15 to determine which of the working cylinders 2, 2a is supplied with hydraulic fluid through conduits 23 or 24 from the pump 17 through a conduit 20. The main control valve 15, 30, Figs. 4 and 5, comprises a housing 15 and a double-ended piston 30 and operates as follows. Assuming the piston of the auxiliary control member 10 to be in a position to admit compressed air to conduit 13 the piston 30 is moved to the right, Fig. 4, of the housing 15 to compress a spring 38 by means of a thrust element 40. With the piston in the righthand position hydraulic fluid is supplied from the pump 17 through conduit 20 and connection 19 past an annular groove 32 formed on the piston 30 through a port 41, connection 22 and conduit 24 to the working cylinder 2a. At the same time the working cylinder 2 is exhausted through conduit 23, connection 21, port 41a and the left-hand chamber formed in the housing 15 at the left-hand end of the piston 30 through a connection 26 leading to the reservoir 16. When the piston 2a reaches the end of its stroke the changeover element 43 is actuated to exhaust the conduit 13, thus enabling the right-hand spring 38 and member 40 to push the piston 30 to the central position within the housing 15, as shown in Fig. 5. When the piston 30 is in the central position the conduit 20, attached to connection 19 feeds the hydraulic fluid to the reservoir 16 through the annular groove 32, ports 41 and 41a, the chambers in the housing 15 at each end of the piston 30 and connections 25, 26 leading to the reservoir 16. The conduits 23, 24 attached to the connections 21, 22 are also connected to the reservoir 16 to exhaust the cylinders 2, 2a. When the piston of the auxiliary control member 10 has been completely reversed by the changeover element 43 compressed air is fed to the conduit 14 to move the piston 30 to the right of the housing 15, Fig. 6 (not shown), and in this position the working cylinder 2 is supplied with hydraulic fluid and the cylinder 2a is open to the reservoir 16. In an alternative arrangement shown in Figs. 9 and 10, an auxiliary pump 45 driven by the motor 18 feeds hydraulic fluid, at a pressure lower than that supplied by the pump 17, into the conduit 11 to operate the auxiliary control member 10. An exhaust valve 12 and an excess pressure valve 47 are provided in the pipe 11. In a further alternative arrangement the conduits 13, 14 are replaced by electric cables connected to electromagnets which effect reversal of the slide valve 30.