| 释义 |
- Examples
- Typical use
- See also
- References
{{Use dmy dates|date=January 2018}}{{Refimprove|date=September 2014}}The railway block signalling bell code is a system of bell rings used in Great Britain to communicate between manually operated Signal Boxes (the system is not used in modern power signal boxes, unless it is a fringe box to an older signalbox). Each signal box would have a bell circuit to the box on either side of it along the line. The equipment would consist of a plunger or tapper (rather like a Morse key) which if pressed, rings the bell in the neighbouring box. The neighbouring box would have a key for communicating back, therefore each box has a key which rings the bell in the other box. Where a signal box communicates with more than one other box (in either direction along the line, and possibly along a branch line too), each bell would have a different tone, so that the signalman could tell them apart by ear. Examples Although codes varied from region to region, the following shows a few selected standard UK bell codes: | Code | Meaning |
|---|
| 1 bell | Call attention | | 2 bells | Train entering section | | 2 - 3 bells (2 bells, pause, 3 bells) | Is line clear for light engine? | | 2 - 2 - 1 | Is line clear for empty coaching stock train? | | 3 | Is line clear for stopping freight train? | | 3 - 1 | Is line clear for stopping passenger train? | | 3 - 1 - 1 | Is line clear for express freight train? | | 4 | Is line clear for express passenger train? | | 4 - 1 | Is line clear for mineral or empty wagon train? | | 2 - 1 | Train arrived | | 3 - 3 | Blocking back outside home signal | | 5 - 2 | Release token [for single line sections only] | | 2 - 5 | Token replaced | | 5 - 5 - 5 | Opening signal box | | 7 - 5 - 5 | Closing signal box | | 6 | Obstruction danger | | 4 - 5 - 5 | Train running away on Right Line | | 2 - 5 - 5 | Train running away on Wrong Line | | 16 | Testing bells and instruments |
[1] Typical use These would be used as follows (assuming a simple exchange between two signal boxes on a plain section of line) between two signal boxes A and B. Assume a train is to pass from the block controlled by A to the block controlled by B. This must be agreed and permitted by the signalman in box B. Here is the sequence of bell codes and associated actions: - Box A sends 1 bell to box B. (Call attention.)
- Box B replies with 1 bell to box A. (Acknowledgement, indicating readiness.)
- Box A sends 4 bells to box B. (Is line clear for express passenger train?)
- Box B sends 4 bells to box A. (Acknowledgement, if in the position to accept the train giving permission for box A to signal the train into the block controlled by B.)
- (when the signalled train enters the portion of line between A and B.) Box A sends 2 bells to box B. (Train entering section.) This is sent as the train passes box A and enters the block controlled by B.
- Box B sends 2 - 1 bells to box A. (Only after confirming that the train has arrived complete and no portion of it remains within the block section between A and B or the clearing point for that section. This could be done by the guard of the train notifying the signalman or by the signalman observing the tail-lamp.)
See also - Bell codes are used on multiple unit trains for communication between drivers and guards, but are not the codes listed above.
- Whistle codes are used by railway engines to communicate with signal boxes and other staff.
References1. ^"BR Regulations for Train Signalling 1st Oct 1960"
- Information about "standard" UK bell codes and variations on www.signalbox.org
{{UK-rail-transport-stub}} 1 : Railway signalling block systems |