Patent GB-680644-A (GB)
Title: Improvements in ballast-tamping machines for railway tracks
IPC: E01B27/16
Filed: 1949-12-12
Abstract: 680,644. Tamping railway ballast. CONSTRUCTIONS MECANIQUES SOC. ANON. RENENS, and ZURMUHLE, E. Dec. 12, 1949. [Dec. 10, 1948] No. 31831/49. Class 104 (ii). The vibratory tools of a railway track tamping machine are arranged in pairs which are located on opposite sides of a sleeper and advanced towards each other and subsequently retracted by hydraulic driving means. The machine comprises a vertically movable tool frame or carrier 1, Fig. 1, in which is journalled an eccentric shaft 2 connected to a pair of oppositely disposed eccentric arms 3, 31, the outer ends of the latter being pivotally connected to levers 4, 4<SP>1</SP>. Levers 4, 4<SP>1</SP> are pivoted at 6, 61 respectively to external flanges on a pair of horizontal cylinders 8, 8<SP>1</SP>, and the lower ends of the levers are formed as tamping tools 5, 5<SP>1</SP> adapted to be located on opposite sides of a sleeper. The cylinders 8, 81 are guided upon a common plunger 10 fixed at its central portion to the tool carrier 1, and the outer ends of the cylinders 8, 8<SP>1</SP> form plungers 9, 91 which work within fixed cylinders 13, 13<SP>1</SP> carried by bolts 11, 111 and 12, 12<SP>1</SP> secured to the tool carrier ; these bolts also engage guiding sleeves 14, 14<SP>1</SP> mounted on the cylinders 8, 81. In operation the carrier 1 is oscillated vertically relative to the track and at the same time the structure comprising the parts 4-9 and 14 reciprocates horizontally relative to the carrier 1. The hydraulic system whereby the cylinders 8, 8<SP>1</SP> are moved inwardly together with the tamping tools comprises an oil pump 15, Fig. 2a, associated with a slidable-plunger control-valve operated manually by a lever 19, movement of the lever to the left acting to connect the pump, through a pipe 23 to a second control slide valve 28 and also connecting a fluid return pipe 24 to a pipe 25 leading to a sump 16. With equal loads or resistances acting on the tamping tools the plunger 29 of valve 28 occupies a central position and allows pressure fluid to be fed equally through a pipe 42 to a control valve 47 associated with one pair of tampers, and through a pipe 39 to a similar valve 47a associated with another pair. Valve 47 controls the pressure fluid through pipes 58, 59 to the cylinders 13<SP>1</SP>, 13, causing the plungers 9<SP>1</SP> 9 to be moved towards one another, with corresponding movement of the cylinders 8<SP>1</SP> 8 on which the tamping tools are pivoted. As shown, the two pairs of cylinders 8<SP>1</SP>, 8 and 8a<SP>1</SP>, 8a on opposite sides of the carrier head carry oppositely directed rack bars 52, 53 and 52a, 53a respectively, with pinions 51 and 51a located between the racks of the respective pairs. The axle of pinion 51 is engaged by a fork at the lower end of a lever 50 which is connected to a link 49 at the end of plunger 48 of valve 47, there being a similar connection between pinion 51a and plunger 48a of valve 47a. The arrangement is such that, in the event of one tamping tool of a pair encountering greater resistance than the other, the resultant unequal rate of movement of the rack bars, e.g. 52, 53, swings the lever 50 so that plunger 48 is moved to open further the requisite valve port leading to cylinder 13<SP>1</SP> or 13, and throttle the other. At the same time a retroactive effect is produced by a link 36 connected to cylinder 8, which swings a bellcrank 35 and upsets the equilibrium of a system comprising a link 34, and levers 32, 31, whereby the plunger 29 of valve 28 is moved from its central position, allowing extra pressure fluid to be admitted through pipe 42 to valve 47. A similar result would be achieved by unequal resistance to the tamping tools associated with cylinders 8a, 8a<SP>1</SP>. Axial bores 63, 63<SP>1</SP> interconnect the cylinders 8, 8<SP>1</SP> and connect through a pipe 64 to an overflow valve 65, the cylinders 8a, 8a<SP>1</SP> having a similar provision via a pipe 64a. The tools are retracted by movement of lever 19 to the right. Specifications 403,256, 406,064, and 421,549 are referred to.