Tokenless Block Instrument (Handle Type) for Single Line - Part 1

HANDLE TYPE TOKENLESS BLOCK INSTRUMENT 
FOR SINGLE LINE IRS SPECIFICATION NO. IRS-S-98-2001

Before we start TLBI Handle Type , We Should Know the Disadvantage Of Single line Token instrument over TLBI OR Need of TLBI in signal Line.

1. Tokens are to be exchanged between Station staff and Train driver.
2. This required more operating time when train is already standing inn the station, because tokens has to be collected from the incoming train and then put that token into the block instrument for closing the block section and to take fresh line clear and token.
3. More physical strain  as token are to be exchanged.
4. Problem like token missing , token balancing etc frequently encountered.
5. Unwanted detentions because of token system.
6. Less section capacity.

Introduction :

- The Signal Standards Committee in the 29th Report recommended the introduction of Tokenless working on the Indian Railways to increase the single line capacity and the same was accepted by the Railway Board.

-  The first pair of Tokenless instruments supplied by the Diado Signal Company of Japan was introduced in 1959-60 on the Khurda Road - Ratang Section of the South Eastern Railway(Presently East Cost Railway). 

- The Last Stop Signal is Authority to proceed with TLBI.

- DC Current or Voltage are not used for signalling to the other station by TLBI to avoid other interference by extraneous currents.

- TLBI uses Modulated Carrier frequencies for Setting the instrument to TGT, TCF, TOL and Line Closed Condition.

- Transmitter and Receiver are used to transmit or receive carrier frequency .

- The instruments are designed to work either on 1800 Hz or 2700 Hz Carrier frequencies.  The Modulating frequencies are 85 Hz and 65 Hz and these are common for all the instruments.


COMPONENTS OF TLBI: