288,168. National Automatic Tool Co., (Assignees of Gallaway, R. M.) April 2, 1927, [Convention date]. Drilling - machines.-A drilling or like machine having a member hydraulically reciprocated on guides, comprises two hydraulic cylinders whose piston rods are attached to the member on each side thereof and at a point between the centre of gravity of the member and the guides. As applied to a multiplespindle drilling-machine a vertical pillar 2, Fig. 1, carries guides 6 for a drill-head 5, the spindles (not shown) being rotated by a splined spindle 16 driven through gearing in an overarm 3 from a vertical shaft 14 driven through gearing 9, 12 from an electric motor M. The motor also drives a gear-pump P which draws fluid (preferably oil) from a sump S and delivers it by a pipe 29 to two hydraulic cylinders 17 arranged at each side of the head 5, the piston rods 23 of the cylinders being attached by adjustable nuts 27 to lugs 25 on the head arranged mid-way between the guides 6 and the centre of gravity g of the head. The supply of fluid to the cylinders is controlled by a master valve V which ia under fluid pressure or hand control, the arrangement being such that when it is actuated by a hand-controlled valve or lever mechanism to commence a cycle of movements of the drill head, the action of the valve continues automatically until the cycle is completed and the heal is brought to rest in its inoperative position, arrangement being also made for stopping the movements of the head at any point of the cycle in case of emergency. The valve comprises a casing 37, Fig. 3, enclosing a piston 42 attached to a rod 43 carrying at its upper end a differential piston 49. A pipe 51 is connected to the supply pipe 29 so as to maintain pressure constant.y under the smaller area of the piston and tend to keep the piston 42 in its raised position indicated by dotted lines in Fig. 3. The valve assumes this position on the completion of a cycle of movements, and to initiate a new cycle the operator depresses a button 68, Figs. 1 and 6, situated at the end of a tubular casting 57 depending from the overarm 3. This raises a piston 63 against the pressure of a spring 70 and allows fluid to proceed from the supply pipe 29, which passes down the casing 57, through a central passage 60, transverse passage 65 and the annular space 63x round the piston to a port 73 connected to a pipe 56 which proceeds through the casing 57 to the top of the cylinder 50, Fig. 3, containing the piston 49. The piston 42 is then depressed to the full line position shown in Fig. 3, and during its movement two trip dogs 45, 46 snap, under the pressure of springs 45<s>, behind a collar 44 on the rod and maintain it in its lowest position. The supply pipe 29 is then connected by the annular space 42<x> round the piston to a pipe 34 leading to the tops of the cylinders 17 and also to a second port leading through an adjustable needle-valve to a pipe 35, Fig. 1, joined to the pipe 30 which is connected to the tops of the cylinders 17. This causes a rapid downward movement of the drillhead, and when the latter has almost reached its working position an adjustable dog on the head engages the end 45a of the trip 45, depressing it against its spring out of the path of the collar 44 and allowing the piston 42 to be raised by the piston 49 to an intermediate position with the collar 44 resting against the trip dog 46. In this position fluid supply to the pipe 34 is cut, off but a reduced supply proceeds to the cylinders 17 by the needle-valve and pipe 35 to feed the tools slowly through the work. When the drilling operation is completed a second adjustable dog on the drill head depresses the trip 46 and allows the piston 42 to return to the dotted line position, whereupon the supply 29 is connected to a pipe 33 leading to the bottom ends of the cylinders 17 and causes a rapid withdrawal of the toolhead, exhaust taking place from the tops of the cylinders by the pipe 34 and an exhaust pipe 85. During downward movement of the drill head the lower ends of the cylinders exhaust through the pipe 33 and the hollow centre of the piston 42 to the pipe 85 and thence to the sump S. Should it be desired to return the tool-head to its inoperative position before the cycle of movements is completed, owing to breakage of a tool &c., a second button 69, Fig. 6, is depressed against a spring 71 and allows fluid to pass from the central passage 60 through a port 81 to a pipe 80 located in the casing 57 and leading to a cylinder 77, Fig. 3, enclosing a piston 78. Fluid in the cylinder 77 moves the piston against the pressure of a spring 83 and withdraws the trip 46 from the path of the collar 44, the trips 45, 46 being connected by a pin and slot which allows the trips to have independent movements as described above, but which causes both trips to be withdrawn by the piston 78 and allows the piston 42 to be moved to its uppermost position to cause a rapid withdrawal of the tool-head. Exhaust from the cylinder 50 takes place through the pipes 51, 56, ports 73, 81, and ports 74, 82 above the pistons 63, 64, leading to the interior of the casing 57, from the top of which an overflow pipe 76, Fig. 1, leads to the sump S. The emergency stop button 69 is arranged to project beyond the starting button 68 so as to be more readily accessible to the operator in case of emergency. In a modification the master valve V is controlled directly by hand, a bracket 105, Fig. 10, being then attached to the pillar 2 and providing the fulcrum 106 for a hand lever 100. With the parts in the position shown in Fig. 10, a cycle of operations is started by moving the lever in the direction of the arrow d whereupon a link 114 attached to the lever rocks a bell-crank lever 109 against spring 115 and lowers the rod 43, with piston 42 attached, to the lowest position. the trip dogs 45, 46 snapping behind the collar 44 as described above. The adjustable dogs 53. 54 on the tool head act as before on the trip dogs 45, 46 to move the piston 42 in stages, the upward movement of the piston being in this case caused by a spring 101 engaging a fixed lug 102 und a collar 103 on the top of the rod 43. To stop the cycle of operations at any intermediate point, the lever 100 is rocked in the direction of the arrow e, whereupon a slot 113 in the link 114 rides over the pin 112 on the bell-crank lever 109 while the end of the link engages a lever 116 and rocks it, about the pivot 117 to withdraw the trip dogs 45, 46 out of the path of the collar 44.