Single Line Electrical Block Instruments PDF

CHAPTER - IV SINGLE LINE ELECTRICAL BLOCK INSTRUMENTS DESCRIPTION AND METHOD OF OPERATING 4.01 Types of Instruments – The following types of Electrical Block Instruments are in use on the Eastern Railway where Single Line working is in force-...

CHAPTER - IV SINGLE LINE ELECTRICAL BLOCK INSTRUMENTS DESCRIPTION AND METHOD OF OPERATING 4.01 Types of Instruments – The following types of Electrical Block Instruments are in use on the Eastern Railway where Single Line working is in force- (a) Neale’s Token Instrument (Old/converted type) (b) Neale’s Token Instrument (New type) (c) Tablet Instrument (d) Tokenless Instrument (i) Handle type – (Daido & Kyosan) (ii) Push Button type. Note :- Tokenless Instruments have been dealt in Chapter VIII of BWM. 4.02. Description of Instruments - In the following pages will be found a description of each of the above types of instruments together with instructions for their operation. 64 4.03. Neale’s Token Instrument (Old type) – This instrument is illustrated and is provided with the following. (a) an Operating Handle. (b) A Bell Plunger (c) A Block Bell (d) A Current Indicator ( Galvanometer) (e) Drawer (f) Lock on Drawer (g) A token Delivery Aperture (h) A Mechanical Key Lock (i) A glass window for observing when Tokens are running short. 4.04. The Operating Handle is circular disc with a pointer engraved on it as shown below :- (a) The Pointer indicates the three positions of the Operating Handle – (i) Line Closed which is the normal position of the handle and indicates that no Token has been extracted at either end of the Block section which is therefore clear of trains. (ii) Receiving position TCF which indicates that Line Clear has been given for a train to approach and that a Token has been extracted at the other end of the Block section, and (iii) Sending position (TGT) which indicates that line clear has been received to despatch a train and a Token has been extracted from the instrument. (b) The Operating Handle cannot be turned without the permission of the Station Master at the other end of the Block section who has electrical control over it. 4.05. Bell Plunger – The Bell Plunger is placed in the centre of the Operating Handle and when depressed rings the bell of the corresponding Block Instrument at the other end of the Block section. It shall only be employed for signalling trains by means of the prescribed code of Bell signals. Each depression of the Bell Plunger causes one beat on the bell of the corresponding Block Instrument at the other end of the section. 65 4.06. Block Bells – These bells are provided to convey the prescribed Code of Bell signals. 4.07. Current Indicator or Galvanometer – The Galvanometer is provided with a needle the movement of which indicates the passage of an electrical current received or sent and also the operation of the corresponding Block Instrument at the other end of the section. 4.08. Drawer – This provides the means for inserting a Token into the instrument and is so formed that only the correct Token can be inserted. 4.09. Lock on Drawer – This lock where provided to enable the Drawer to be locked by the Station Master when he leaves the office or cabin. The keys shall always remain in the possession of the Station Master on duty. 4.10. Token Delivery Aperture – This is the opening at the bottom of the instrument through which tokens are obtained. 4.11. Mechanical Key Lock – The Mechanical Key lock is an attachment to the Token instrument added where required for the purpose of providing an interlock between the Token Instrument and the Starter signal of the section which it controls. It may also be used for other purposes such as the control of outlying points. The key can only be removed from the lock after the Token has been extracted from the instrument and the removal of the key locks the operating Handle in the sending position. 4.12. Glass Window – This provides a means whereby the station Master can observe whether the Tokens are falling short. 4.13. Description of Tokens- (a) The Tokens used in this instrument are of the ball type with grooves cut into them, these grooves being of a different pattern for adjoining Block section. (b) Each Token has engraved on it the Code initials of the two stations at either end of the Block section to which it applies. Every Token also bears a distinctive number. 4.14. Method of signalling trains from Block station to Block station with Neale’s Token Instrument (Old type) – Before any operation on Token or Block Instrument is made the name of Stations working together shall be exchanged on the telephone one with the others, as an assurance that the correct stations are in communication. Taking two adjacent station X and Y and supposing that a train is to proceed from X to Y and the Operating Handles of the Token Instruments at both stations are normal, the following is the sequence of operations for signalling the train. Station X Station Y (1) Sends “Attention” signal to Y (giving name of station on the telephone). (2) Acknowledges “Attention” signal to X (giving name of station on the telephone). (3) Attends Telephone. (4) Attends Telephone. (5) Asks Y for a Private Numbers for the train. 66  (6) Y gives a Private Numbers to X. (7) Sends Y “Attention” signal. (8) Acknowledges “Attention” signal to X. (9) Sends “Is Line Clear” signal inquiry to Y, keeping the Bell plunger pressed in for a count of five on the last stroke. (10) On the last beat of X’s “Is Line Clear” signal turns the operating Handle of his instrument to the ‘Receiving’ position and acknowledge the “Is Line Clear” signal to X keeping the Bell Plunger pressed in for a count of five on the last stroke. (11) Turns the Operating Handle to the “Sending” position on receipt of the last beat of Y’s acknowledgement signal. This will release a Token from the instrument, which he shall intimate to Y by giving the “Attention” signal (one beat). (12) Sends “Attention” signal to Y on departure of the train with the token. (13) Acknowledges “Attention” signal to X. (14) Sends “Train entering Section” signal to Y. (15) Acknowledges “Train entering Section” signal to X. (16) Obtains the Token from the Loco Pilot on arrival of the train and places it in the instrument. (17) Turns the Operating Handle of the instrument to the “Line Closed” position. (18) Sends “Attention” signal to X. (19) Acknowledges “Attention” signal to Y. (20) Sends “Train out of Section” signal to X keeping the Bell plunger pressed in for a count of five on the last stroke. (21) On the last beat of Y’s “Train out of Section” signal turns the Operating Handle of his instrument to the “Line Closed” position and acknowledges “Train out of section” signal to Y. 67 4.15. Neale’s Token Instrument (New Type) – the following is an illustration of this type of instrument. (a) The operating Handle indicates “Coming From” and “Going To” in place of “Receiving” and ”Sending”. (b) When there is no Token in the instrument the Operating Handle can only be moved to the “Coming From” position. (c) The Token is inserted by placing it in a drum at the top of the instrument and drum must be revolved to allow the Token to drop into the Token Chamber. (d) Four small circular glass windows are provided in place of the rectangular window in the old instrument for observing whether Tokens are running short. (e) A shutter is provided which gives two indications- (i) A green Disc with a white cross to indicate that there are one or more Tokens in the instrument, and (ii) A red disc with word “Empty” on it to indicate that there is no Token in the instrument. (f) the Tokens instead of having grooves of different patterns for adjoining Block sections have holes of different shapes. (g) The difference in the operation of the two instruments is that with the old type the Station Master giving the “Line Clear” for a train to approach is the first to restore his operating Handle to normal while with the new type the reverse is the case. 4.16. Method of signalling trains from Block station to Block station with Neale’s Token Instrument (New Type) – Before any operation on Token or Block Instruments is made the names of the stations working together shall be exchanged on the telephone one with the other as an assurance that the correct stations are in communication. The method of signalling trains from Block station to Block station is exactly similar to that laid d won for the Neale’s Token Instrument (Old Type) until the operation of sending Train out of Section signal is arrived at when the procedure differs slight as below. 68  Station X Station Y (17) Sends “Attention” signal to X (giving name of station on the telephone). (18) Acknowledges “Attention” signal to Y (giving name of station on the telephone). (19) Sends “Train out of Section” signal to X keeping the Bell Plunger pressed in for a count of five on the last stroke. (20) On the last beat of Y’s “Train out of Section” signal turns the Operating Handle of his instrument to “Line Closed”. (21) Acknowledges “Train out of Section” signal to Y keeping the Bell Plunger pressed in for a count of five on the last stroke. (22) Turns his Operating Handle to “Line Closed” on the last beat of X’s acknowledgement signal. 4.17. Neale’s tablet instrument. – The following is an illustration of this type of instrument. This instrument differs from the Neale’s token (new type) instrument in the following respects. – (a) a flat tablet is used in this instrument as a token instead of a ball. The tablet is a metal disc and is engraved with the code initials of the stations at each end of the block sections to which it applies. The Tablets are provided with different grooves so that they cannot be put in to the instruments other than those to which they relate. The Tablets are numbered serially. (b) the tablet is issued from a drawer instead of an aperture ; 69  (c) a small rectangular shutter is provided to show whether there are tablets in the instrument or not. If there are less than five tablets, these will not be seen. 4.18. Whenever a single line Block Instrument is opened by the Inspector/Maintainer of signal department for the purpose of maintenance – it shall be done only in the “Line Closed” position of the instrument. A register is to be maintained and Cabinmaster/SM and the staff of signal department shall sign mentioning date and time of opening. The Cabinmaster/SM in charge of the cabin/station shall immediately advise the station in rear duly exchanging Private Numbers that the Block instrument has been taken on maintenance. During the period the Block Instrument is under such maintenance “Line Clear” will not be signalled on the Block Instrument and trains to be passed according to rules for failure of Block Instrument according to Chapter II of BWM. On completion of Inspection/maintenance the instrument shall again be closed padlocked and sealed in “Line Closed” position and the Cabinmaster/SM and the signalling staff will both sign the register in acknowledgement that the Block Instrument has been sealed and padlocked. The Cabinmaster/SM in charge of the cabin/Station shall not however resume normal working on the block instrument unless Private Numbers has been exchanged with Cabinmaster/SM of the block station in rear in confirmation that no train is in the block section or the last train leaving the rear station on Private Numbers has cleared the section. 70