797,044. Packing railway ballast. PLASSER F., and THEURER, J. Nov. 17, 1954, No. 33306/54. Class 104 (2). A machine for consolidating the ballast bed under railway sleepers comprises a plurality of tamping tools 6, Fig. 2, mounted on a vertically adjustable carrier 2 on a trolley, with their upper ends pivotally connected to oscillatory tool holders 5 each of which is associated with at least one pair of tools 6, the tools being also pivotally connected at an intermediate point along their length, e.g. as shown in Fig. 4, to operating means which is actuated by fluid under pressure to reciprocate the tools towards and away from each other in the longitudinal direction of the rails, the operating means for each tool consisting of a piston and a cylinder movable relative to one another, one being secured to the tool carrier and the other connected to the tool. As shown in Fig. 2, the machine comprises a vehicle frame 1 provided with vertical guide columns 3 for the tool carrier 2 which can be lowered to bring the pairs of tools 6 into operative position on opposite sides of a sleeper 9 and, after completing the packing operation at that sleeper, lifted to allow the machine to travel forward to the succeeding sleeper. The eccentric shaft 4 which oscillates the tools to which it is linked by tool holders 5, is coupled by a V-belt to an electric motor 11 mounted vertically above it, both ends of the motor shaft having a belt drive to the respective ends of the shaft 4, Fig. 3 (not shown). Vertical movement of the tool carrier 2 upon the fixed guides 3 is effected by forming the intermediate portions of the latter as pistons 20 which are located within guide cylinders 20a fixed within the carrier 2, the pressure medium being either pneumatic or hydraulic. In the example the pressure medium is oil, and the tool carrier 2 is constructed as an oil container upon which is mounted an oil pump 12 driven from the motor 11 by a belt 13. Oil fed through bores 17 in the columns 3 operates to raise the tool carrier 2, lowering being effected by feeding oil through the lower bores 17a. Fig. 4 shows an arrangement wherein the pair of packing tool arms 6 located at opposite sides of a sleeper are each pivotally mounted on a member 7 on the side of a cylinder 21, the cylinders being closed at both ends and slidable in either direction along a piston rod 22 which is. fixedly mounted parallel with the track rails and has a pair of fixed pistons 24 which serve to divide their relative cylinders into two chambers 30, 31 respectively. Oil under pressure is supplied to the inside of the outer chambers 30 through conduits 23 bored axially through the piston rod 22, the inner chambers 31 being supplied similarly through conduits 25; the cylinders are moved to bring the tools inwardly towards one another when pressure oil is supplied to the chambers 31 and, conversely, the tools move outwardly when pressure is supplied to the chambers 30. Since the hydraulic arrangement provides a slow movement under considerable pressure it is preferable in effecting the closing movement, but the opening movement is preferably accelerated by a spring 26, Fig. 6, provided in the outer chambers 30 instead of feeding pressure oil thereto. A control system for this arrangement comprises a piston valve 33, Fig. 6, with two pistons on a piston rod which is linked to a manual control lever, the pistons being so arranged that in one position they permit oil from a pressure pump 12 to be admitted to pipes connected to chambers 31 of pairs of tamping- tool cylinders 21 associated with each of a pair of rails, and in the other position they close the outlet from the pump through the control valve cylinder so that the oil flows through return conduits 25a, 25b back to a storage chamber 38. In a modification, Fig. 7, a piston valve 37 controlled by a lever 36 is arranged, in the position shown, to pass oil that is fed by a pump 12 from a container 38 to a conduit 25 connected to axial bores which feed oil to the chambers 31 of cylinders 21 slidable upon rigid piston rods provided with fixed pistons 24. The chambers 30 on the other side of the pistons 24 are connected to compressed air supply conduits 23 fed by a compressor 46 and operating to move the tamping tools outwardly when the control lever 36 is moved to position II, whereby the slide valve is positioned to allow pressure oil from the pump 12 to return through a conduit 40 back to the container 38. Safety valves 39, 43 in the compressed oil and air supplies respectively prevent excessive build-up of pressure. The chambers 30, 31 defined by the pistons 24 are sealed by two packing-rings on the pistons, Fig. 8 (not shown), and an additional bore is provided through the piston rod and connected to a peripheral groove located between the packing-rings so that any pressure medium, e.g. oil or compressed air, which enters the groove is either returned to the oil storage container or allowed to escape. Fig. 9 shows a further modification wherein the packing tools are pivoted at 7 to piston rods 22a carrying pistons 24 which are slidable in opposite directions within a common fixed cylinder 47 with openings near its ends for the simultaneous admission of pressure medium through conduits 50, whereby the pistons are moved towards one another together with the tamping tools. Opening movement of the tools is effected by admitting pressure medium through a central conduit 51. In this arrangement the outer ends of the piston rods 22a have a cross-section of the form shown in Fig. 10 and engage within a correspondingly grooved guide boss 52, whereby skewing of the tamping tool arms 6 is prevented. Fig. 11 shows a further modification wherein a fixed cylinder 47 is provided with rigid ends and a central transverse baffle, the latter forming a partial support for a guide rod 22a upon which sleeve-like piston rods of two pistons 24 are slidably mounted. Pressure medium, e.g. oil, is admitted to the cylinder through end conduits 50 for inward movement of the packing tools, and through a central conduit 51 for outward movement. The packing tools are pivoted upon stirrups 53 which are secured on the piston rods by nuts 54, and the stirrups have upward extensions which are apertured for sliding engagement with a horizontal guide rod 22b mounted above and parallel with the guide rod 22. Compressed air may be admitted through the conduit 51 as an alternative to oil for the outward movement of the tools, or springs may be provided. Means are provided for supporting the tool carrier 2 at different heights to alter the depth of penetration of the packing tools, one such means comprising two parts 55, 56 of a cylinder, Fig. 13, one of which is movable relative to the other about its axis whereby a tenon 58 in one is either loosely engaged within a slot 57 in the other, or the tenon lies across the slot at rightangles. Alternatively the engagement of the sloping faces of two oppositely disposed wedges, one of which is movable relative to the other, may be employed to provide a progressive variation in height.