Patent GB-135848-A (GB)
IPC: B21J7/24
Abstract: 135,848. Ateliers Demoor, Soc. Anon. Nov. 28, 1918, [Convention date]. Power hammers.-Relates to a pump piston hammer controlled by two cylindrical valves m, n which are rotated in unison into various positions to give heavy or light blows or to hold the tup up or down, and consists in providing the valve n with a supplementary adjustment which controls the exhaust openings allowing compressed air to pass to atmosphere when it is desired to produce light blows. The upper valve has, in the middle CD, Fig. 3<a>, two sectors 1<a>, 1<b>, cut away leaving- an angled rib 1. The sector 1<b> connects with segments 4<a>, 7<a>, at either end of the valve as shown at AB and EF. The sectors 1<a>, 1<b> can register with ports h, g<1>, r<1> leading respectively to the space i above the reciprocating piston b, the space g above the annular piston of the tup d, and the atmosphere. The port r<1> is extended to register with the segment 7<a> in some positions and segments 4<a> may register with a port o, Fig. 5, leading to the space s. The lower valve n has, in the middle C D, Fig. 3<b>, a double rib 8 leaving a sector 8<a> and ducts 14 and 17. The sector 8<a> communicates by a port 11 and non-return valve 12 with a segment 11<a> at the end A B into which the .duct 14 opens. The port 11 has also an opening or openings 20 which can be closed to a variable extent by a sleeve 21 with opening 24 and handle 23, Fig. 5. The duct 17 opens into a segment 16 having a non-return valve 15. The middle of the valve n registers with ports k, j<1> leading to the spaces l and j, the end A B with the. port p which leads to the port r and the end E F with-the port r<2> leading to the atmosphere. When the valves are in the position shown in Fig. 1, there is free communication between the two cylinders and heavy blows are given; when, as shown in Fig. 2, the space i is open to the atmosphere and the space l is in communication with the space j through ports k, 11, valve 12, Fig. 3<b>, and duct 14, so that the tup is held up; when, as shown in Fig. 3, the space i is open as before but the space l is in communication with the spaces g and s through ports k, 11, valve 12, ports p, r, Fig. 5, and port 5, Fig. 3<a>, duct 1<b> and ports o, g<1> and with the atmosphere through port r<2> valve 15, duct 17, and port k, so that air is drawn from the atmosphere and forced into the spaces s, g firmly holding the tup down, the pressure being increased on the upstroke of the piston b by exhausting the space j through the non-return valve 12; when, as shown in Fig. 4, the space i is partly in communication with the space g and partly with the atmosphere and the space l is in communication with the space j directly through a narrow opening over the rib 8 and indirectly through port 11, valve 12, and duct 14, and is also in communication with the air through ports 20, p, r, duct 1<b>, narrow opening under the rib 1 and port r<1> so that light blows are given varying with the position of the valves and the adjustment of the port 20. A means is thus provided so that variations of the pressure of the air, due to the wear of the pistons, to a variation in temperature, or to other causes, may be compensated for without alteration of the setting of the main valve n itself. In a modification, which does not however permit of adjustment while running, the posts 20 are replaced by ports 18, Figs. 6, 6<a> that can be more or less throttled by a valve 19 adjustable by a screwdriver from the end of the main valve. In the position shown in Fig. 2, the ports 20, p are in communication, but as the port r is closed by a rib 6, Figs. 2 and 3<a>, it has no effect on the action and the tup rises until the plug t closes the opening u.