Patent GB-279189-A (GB)
Title: Improvements in or relating to signalling apparatus used in mines, shafts and like places
IPC: E21F17/18
Filed: 1926-08-05
Abstract: 279,189. Moore, A. E. Aug. 5, 1926. Mine signals.-In a signalling system employing compressed fluid for use in mines, &c., a signalling impulse is obtained by a release of the fluid pressure in the system. In the form of apparatus shown in Fig. 7, in which a single warning device A is operated from any of a number of release valves f, each valve f is arranged to open the pipe line d to atmosphere and so break the balance of pressure on the two sides of a piston b, allowing the piston to move to the right under pressure from a main supply pipe c. This movement opens a valve passage a<15> and admits pressure to a cylinder e whereby a piston e<1> is moved to the left until an exhaust port e<10> exposed. A lever e<8> operating a bellcrank lever on which is a striker for a gong e<13> has a projecting pin engaging the piston e<1> so that each movement of the piston produces one stroke of the bell. The release of pressure is of short duration and the piston b is then restored to its normal position by the pressure being equalized on its two sides through an adjustable by-pass a' in the piston or cylinder wall. Actuating apparatus. The release valve f is operated by a lever f<1> secured to a spindle f<4> on which is slidably mounted a sleeve f<6> provided with cams f<1> , f<19>, so that a rotation of the lever f<1> will cause the cam f<19> to raise a valve f<13> by engagement with a projection or ball f<17>. The pipe line being connected to the space f<11> above the valve f<13>, pressure admitted behind a piston f<7> carried by the sleeve f<6>, causes the sleeve to move to the right ;against a spring f<8> and the ball f<17> to ride up the higher cam f<18>, opening the valve still further. At this point the piston f<7> enters the enlarged bore f<3> and exhausts to atmosphere, but the ball f<17>, dropping behind the cams f<18>, f<19>, is unable to return, though the closing of the valve f<13> has cut off the pressure from the cylinder f<2>, until the return of the lever f<1> brings the cams out of the path of the ball. A piston f<23> in a cylinder f<20> in communication with the space f<11> has a piston rod f<24> engaging the lever f<1> and returns the lever when the valve f<13> is closed. Cables g may be used for operating the levers f<1> and the pressure on the lever ensures the cables remaining taut. Two-way signalling. This may be effected by connecting two release valves by the pipe d and connecting each warning device to the head of the cylinder f<20> of the adjacent valve. The piston f<23> is arranged to cover the port f<21> before the valve f<13> opens on operations of the lever f<1> and thus prevents the release of pressure effecting the adjacent warning device while actuating the remote one. Relay mechanism. In order to avoid the use of long cables for actuating the valves directly, a series of pressure-operated relays may be used. Each relay has two pistons h<2>, h<3>, each side of which is exposed to fluid pressure from the main. A pull on a cable j<1> moves the piston h<2> to the right until a port h<16> through this piston coincides with a port h<14> and exhausts one side of the piston h<3> to atmosphere. The piston h<3> is thus forced to the right and its piston rod h' transmits a pull to another relay or to the warning device directly. The apparatus may be modified in various ways. The piston b may be replaced by a diaphragm, and instead of the air escaping from the orifice a<15> actuating the bell e<13> it may operate a whistle or the movement of the piston may close an electric circuit or give a visual indication. A whistle may be operated by the exhaust from the release valve or relay, or the discharge from the release valve or relay may actuate a bell with which the valve or relay is combined. Each release valve may actuate two signals at different points, and bells along the line d may indicate the ringing of a bell at the remote end. The bell may be arranged to ring repeatedly while the valve is open instead of receiving a single stroke.