GB529024A - Improvements in fluid pressure operated implement - Google Patents

Abstract

529,024. Percussive hammers. APP, O. O. May 19, 1939, No. 15017. Convention date, May 19, 1938. [Class 124] In a percussive hammer air admitted at one end of the cylinder passes along a longitudinal passage to a freely movable throttle valve in the other and tool end of the cylinder said valve controlling the air which passes through a second longitudinal passage to the cylinder base in which works a piston having two cylindrical enlargements spaced by a reduced part. As shown, a cylinder 10 has a series of longitudinal grooves or passages quadrantally arranged and connected to inlet and exhaust ports and passages. The grooves are enclosed by a sleeve 11 provided with exhaust ports 68 leading to an adjustable baffle in the form of an adjustable sleeve 75 provided with ports 78 capable of registering with the ports 68. One of the grooves 62 is for exhaust and communicates with the cylinder bore by ports 66, 67. An air admission port 55 connects the bore 24 of a plug 25 by an annular passage 28 with one of the grooves 56 and thereby to a port 57 leading to a freely movable automatic throttle valve 51 which may be maintained in open position by a rod 41 having a finger piece. The plug 25 has a tapered bore connecting to an air admission chamber 14. From the throttle valve a port 58 leads to another groove 59 communicating with ports 60, 61 leading to cylinder bore. Other grooves 63, 64 are separated by a web 65 and the former is connected to cylinder bore by ports 69 and 70 and bleeder channel 71. The groove 64 is correspondingly connected by ports 72, 73 and bleeder channel 74. A chuck 31 is provided with recesses for balls 36 engaging a reduced part 35 of a tool 34, a spring collar 37 maintaining the tool in position and allowing ready withdrawal. In the normal position of the tool the valve 51 is supported by the air in closed position but the inward movement of the tool in engaging the work moves the valve into open position and air passes through into the groove 59 through the port 60 and by the port 73 into the cylinder outwardly of the part 44 of the piston and moves it to the innermost position. Thereupon air is admitted into the piston chamber to advance the piston in the direction of the tool. Gradually in the advance communication is shut off at the port 70. The bleeder channels 71, 74 are covered and opened respectively to obviate any balanced condition of air in the piston chamber. Air passes into the groove 64 through the port 73 and enters the inner end of the cylinder to cushion the final part of the forward stroke, the part 43 having cut off the supply of air. In the inward movement of the piston the impact is cushioned by dashport action of a chamber 86.