Page 422 - IRSEM_Main Book

Section 9: Maintenance of Single Line Block - Instructions

18.9.1 Single Line Token Instruments

(a) Care shall be taken to see that the safety catch provided near the spring
clutch shaft is in position and functioning properly and free to move about
the fulcrum without any friction.

(b) Token indicator shall be checked to see if it is free to move. The pin shall be
oiled once a fortnight with axle oil medium grade to IS: 1628. Effectiveness
of 'No Token' lock shall be checked. It shall not be possible to take handle
to “Train Going To” position when token indicator shows Red.

(c) Care shall be taken to see that "Train Going To" and "Train Coming From"
locks rocker arm is free to move about its fulcrum pin. The locks shall be
about 1 mm above the rack; if not, the locks shall be changed. The edge of
the lock shall be square.

(d) It shall be ensured that all parts of the instrument, which undergo wear and
tear, are replaced at the time of overhauling.

(e) The locking Pawl shall be checked to ensure that it is correctly shaped,
square ended and the width is 9.5 mm.

(f) Care shall be taken to see that in the case of Tablet instrument, the tablet
holding arm release lever is working satisfactorily and the tablet can be
released only after full rotation and release of the instrument handle in the
Train Going To" position.

(g) It shall be checked that the notches in the rack are correctly shaped and
square.

Note: (i) RDSO Booklet No. STS/E/BTl/IMI may be referred to for detailed instructions
regarding maintenance of Token instruments.

(ii) Stipulation as given in section 7 of this chapter may be referred.

18.9.2 Single Line Tokenless Instruments – Push Button Type: The tests
enumerated in para 18.5.2 shall be carried out during routine maintenance.

18.9.3 Double Line Block Instruments – SGE Type: Locking assembly shall be
replaced during each overhauling irrespective of its condition. It shall also be
ensured that all parts of the instrument which undergo wear and tear are
replaced at the time of overhauling as per approved instructions.

Note: (1) Tests enumerated for Double Line Block Instruments in para 18.6.2 shall also
be carried out during routine inspection.

(2) Maintenance Schedule for Block Instruments are given in Annexure: 18-MS1
in Appendix I. At stations having heavy traffic the Railways may prescribe
more frequent inspections, if considered necessary.

Chapter 18: Block Instruments, BPAC & IBS Working Page 370 of 535