Patent GB-190000183-A (GB)
Title: Improvements in Railway Switch and Semaphore Apparatus.
Inventor: JUSTICE PHILIP MIDDLETON
Filed: 1900-01-03
Granted: 1900-05-19
Abstract: 183. Justice, P. M., [Pneumatic Railway Signal Co.]. Jan. 3. Points and switches. -Relates to pneumatic apparatus for operating and controlling the operation of railway signals and switches. The switch and signal operating mechanisms are interlocked by an ordinary interlocking frame, such as one of the Saxby and Farmer type, but they may be used independently. When used conjointly, the signal is put to safety before the switch is reversed, and the switch is restored to its normal position before the signal is returned to 'danger.' Fig. 21 shows the operating-mechanism of the switch, with tappets H, by which the operating- bars L<1> of the signal and switch are interlocked, as in an ordinary interlocking frame. The relay valves R<20>, R<30>, R<200>, R<300> are diaphragm valves of the construction shown in Fig. 6. The branch X<10> from the supply pipe X<1> communicates with the chamber r<233>, and the port e" with the pipe n<11> &c. In the position shown the valve r<23>, r<22> cuts off the supply from the port e<11>, and opens the port to the exhaust r<02>, but, when the valve is raised against the action of the spring r<30> by air admitted through the pipe p<1> &c., the supply is connected to the port e<11> and the port is cut off from the exhaust. The valve r<23> works within the cylinder r<233>, to which the compressed air from the supply has constant access on both sides, this construction being adapted to prevent condensation and the consequent clogging of the valve. In the operation of the switch, when the bar L<1> is pulled to the left, the tappet H is lowered by the slot l<1> to prevent the movement of inter-related bars, the piston i<10> is lowered in its cylinder I<1>, and the slide valve V<10> is moved to connect the supply X<1> with the pipe o', the har L<1> being stopped when the roller i<2> of the piston i<20> in the cylinder I<2> engages the stop face l<02>. The air impulse through the pipe o<1> opens the relay valve R<30>, and connects the supply branch X<10> through the pipe n<10> with the right-hand end of the cylinder C, so that the piston C and the slide M are moved to the left. The slot m in the slide M reverses the switch S, which is locked in the extreme positions bv the dogs s<10>, s<01> of different shape engaging in corresponding notches in the locking-bar S'. The slot m<1> in the slide M moves the slide valve D, to connect the pipe d<10> with the operating-pipe k of the relay valve R<300>, which, when opened, permits air from the branch x<300> of the supply pipe to raise the piston i<20> clear of the stop face l<02>. The piston also acts on the inclined slot l<21>, and completes the movement of the bar L<1> to its extreme position. The operation from reverse to normal is similar, the valve V<10> connecting the supply pipe X<1> to the pipe p<1> to open the valve R<20>, which admits air through the pipe n<11> to the left-hand side of the cylinder C. The slot m<1> also sets the valve D to connect d<11> and j for the purpose of opening the valve R<200>, to disengage the piston i<10> from the stop face l<12> and complete the movement of the bar by the slot l<20>. A pawl and ratchet mechanism (not shown) is also provided in connection with the bar L', to ensure that the bar shall make its full stroke in one direction before it can be moved in the opposite direction. The valve arrangements are such that the connecting-pipes are open to the atmosphere when the parts are in extreme position.