Patent GB-623053-A (GB)
Abstract: 623,053. Railway signalling. WESTING- HOUSE BRAKE & SIGNAL CO., Ltd., PETER, L. H., and COLEY, J. P. Oct. 11, 1946, No. 30383. [Class 105] Where coded-rail current apparatus, for train control and cab signalling is installed only for the stretch between distant and home signals but not for the stretch between the home signal and the distant signal next ahead there are provided at the exit and entrance of the stretch between the distant and home signals track magnets which operate a train-carried receiver whereby the train apparatus is prevented from giving an action corresponding to the absence of coded railcurrent during travel between a home signal and the distant signal next ahead but is restored to a state to give an action in correspondance with coded rail current on entry to the stretch between the next distant and home signals. The stretch between a distant signal 3 and a home signal 2 has track sections AT, BT to which rail current is respectively applied coded at a rate corresponding to the aspects of the distant and home signals. The train apparatus, Figs. 2 and 3 includes relays HR, HHR, DR which are energised through a decoding apparatus on receipt of code, the relay DR responding only to code of 180 interruptions per minute (home signal at clear) relay HHR only to code of 120 interruptions (distant signal lowered) but relay HR responds to both these codes and also to 75 code (distant signal up and home signal at danger). The received coding pulses actuate a contact 9 at the particular rate. The train apparatus also includes contacts 7, 8, 11 which are moved to the right hand (dotted) position on passage over an entrance track magnet 5 at the distance signal 3 but restored to the left hand (full line) position on passage over an exit track magnet 6. On passing the distant signal in the " off " (lowered) position a train receives 120 code in section AT whereby the relays HR, HHR are energised. As the train proceeds and enters section BT it receives 180 code (the home signal 2 being "off") so that relay DR is then energised together with relay HR while relay HHR remains energised by its own stick contact and a front contact of relay DR, Fig. 2. On passage over the exit magnet 6, the contact 7 returns to the left hand position to maintain the relays HR, HHR, energised over their stick contacts and the contact 7 whereby during travel in the non-coded stretch beyond the home signal the cab indicator continues to show the state of the distant signal last passed. On reaching the next distant signal and passing over the entrance track magnet 5 the contact 7 is moved to the right hand side so breaking the stick circuit of relays HR, HHR, which now respond to the particular code present in the new section AT If the distant signal is "on," i.e. at caution only the relay HR is energised and this is stuck on entry to section BT. The brake valve magnet MV. Fig. 3, is energised during travel through sections AT, BT by contact 8 at the right and a front contact of relay HR ; it being noted that section BT has 75 code applied if the home signal 2 is at danger ; but during travel to the next distant signal the magnet MV is energised over contact 11 at the left and a front contact b of a stick relay R picked up only if relay DR is closing its front contact b, i.e. home signal at clear, at the time of leaving the section BT. The condition of the home signal last passed, if at clear, is indicated in the cab during travel to the next distant signal by a green lamp lit over a front contact of the relay R. If the home signal is at danger at the time of leaving section BT, the magnet MV becomes de-energised and the brakes are applied. A single-stroke bell signal may be given in the cab when the train passes the distant signal, this being effected by contact 7 at the right hand.