Patent GB-803455-A (GB)
Title: Improvements in compound hammer
Inventor: KUPKA JOHN JOSEPH
IPC: E02D7/10
Filed: 1957-02-19
Abstract: 803,455. Steam hammers; valve gear. McKIERNAN - LERRY CORPORATION. Feb. 19, 1957, No. 5629/57. Classes 122 (2) and 122 (3). [Also in Group XXI] A compound steam or air hammer comprises in combination a differential piston-ram 21, 22 operating in a differential cylinder 16, 18, the lower wall portion of the larger cylinder and the upper part of the smaller piston forming an annular expansion chamber 24, an admission valve 27 which is arranged to supply motive fluid to the chamber 24 when an actuating member 28 is engaged by the ram as the latter nears the end of its down stroke, a valve for transferring partially-expanded motive fluid from the expansion chamber to the cylinder above the ram, and means for actuating the transfer valve as the ram approaches the upper end of its stroke. Motive fluid supplied at 25, Fig. 1, is admitted to the expansion chamber 24 by a double balanced poppet-valve 27 through ports 35 as the piston shoulder 29 contacts the roller 28 of the actuating member 40 of the admission valve 27. A cylinder 56, Fig. 5, containing the lower and larger piston of a differential piston valve 49, 50 is connected by a small bore 57 with the motive fluid admission passage 42 from the valve 27 so that pressure is put on the lower face of the piston 50 when the admission valve 27 is opened, thus moving the piston valve to the piston shown in Fig. 5. Exhaust ports 51, 53 and 52, 54 are then opened to atmosphere via exhaust pipes 58 branching from either side of the differential piston valve casing 59, allowing the motive fluid to exhaust from above the ram piston 21 via passages 60 during the upstroke. As the piston ascends, the admission valve 27 closes, upward movement continuing by expansion after cut-off. At about threequarters of the upward stroke, the upper end of the ram piston 21 engages a ball 30 carried by the spindle of a pilot vlave 31, Fig. 1. This valve allows a flow of motive fluid from a chest 26 via the cast-in tube 47, Fig. 7, and flexible conduits 32, 33 to the top of the piston valve 49, 50 which is thereby actuated to close the exhaust ports 51, 53 and 52, 54. During the downward movement of the piston valve 49, 50, a cam 63, Fig. 5, on a strut 64 connecting these pistons engages a roller 65 on the end of the hollow stem 66 of a compounding or transfer valve of the double balanced poppet-type having spaced annular faces 67, 68 engaging with seats 69, 70 to govern the flow from relief ports 71 formed in the side of the upper cylinder and leading to a space 72 connected with the differential valve casing 59 which is in communication with the upper cylinder through the passages 60. When the transfer valve 67, 68 is opened by the downward movement of the piston valve, partially-expanded fluid passes from the annular expansion chamber 24 to the top of the upper cylinder to cushion the upstroke of the ram and to apply the remaining energy of the working fluid to drive the ram downwards until the admission valve 27 is again opened, when the ram-position 21, 22, and the piston valve 49, 50 both ascend as the cycle is repeated. The annular space 24 beneath the shoulder 23 of the piston ram permits overtravel in the event of the pile falling from beneath the ram, but damage to the hammer is obviated by trapping cushioning motive fluid beneath the piston 21 after it has passed the inlet ports 35. The admission valve 27, pilot valve 31 and piston valve 49, 50 are each in the form of separate independent units which can be bolted on or removed from their seats 79, 80, 81, Fig. 7, on the side of the main cylinder. A single opening, 82 in the cylinder is provided for entry of the guide sleeve in which the admission valve stem 40, Fig. 1, operates. The cage 84, carrying this guide and the valve 27 and the valve seats, is secured in the mounting seat 79, Fig. 7, by stub bolts 85, Fig. 1. The cover 86 is secured by bolts 88 and it carries a stud 89, Fig. 1, forming an abutment for the valve-closing spring and itself carries a cross-pin 90, the stem being slotted at 91 to ride over the pin to hold the roller 28 at the inner end of the stem in alignment with the ram. The piston valve case 59 is secured in place by four bolts 92, Fig. 1, the transfer valve cage and valve-carrying member 93, Fig. 5, being formed as an integral inner extension of the valve case 59. The closing spring 94 of the transfer valve is located within the hollow stem and is engaged by a positioning and abutment stud 95 on the wall of the cylinder. The piston valve 49, 50, is held against turning by a guide 96 in the casing 59 to engage a face 97 and to provide reaction to the sidethrust on the valve imposed by the spring 94 of the transfer valve. The movements of the piston valve are cushioned by resilient pads 74 inserted at the ends of the upper and lower cylinders 55, 56, the pistons 49, 50 contacting plates 73, 75 respectively. The plate 73 also acts as a valve element to release residual fluid left in the supply conduit 33 from the pilot valve 31. The plate 73 engages an annular ridge 76 on the upper end of the cylinder 55. The plate lifts against the resilient pad 74 to allow excess fluid to escape to a discharge nipple 78, Fig. 2.