Page 283 - IRSEM_Main Book

(ii) It is a good practice to operate the catch handle several times, both in
the normal and the reverse positions, in the case of catch handle
locking and operate the lever several times in the case of Direct Lever
Locking before the notches are actually marked. While doing so, the
catch block shall be properly held against the quadrant.

(d) Notches shall be cut to proper sizes and shapes as marked. Normal and
reverse notches for point levers and those signal levers which have back
tails or long leads may be cut with a small clearance up to 1 mm. Notches
of straight edge locks may have a clearance up to 3 mm for the straight
edge of the lock.

(e) Joints in interlocking bars shall be avoided as far as possible. Where
necessary, the joints shall be made smithy welding. The welded bars shall
be kept truly straight and perfect in shape.

(f) All locks and driving pieces shall be securely fixed square to the
interlocking bar. Locks (dogs) shall have free movement in the channels
of the locking box.

(g) Unsupported and long interlocking bars spanning more than 10 levers in
SA1101 Lever Frame and 7 levers in SA 530 Lever Frame shall be
provided with a carrier lock or dummy pieces.

(h) Any top piece fixed in the plunger shall be ordinarily rivetted except when
it is accessible from outside, it shall be welded on to the plunger.

(i) Each assembled interlocking bar shall be checked and tested to see that -
(i) It is in accordance with approved Locking Diagram.

(ii) The locking provided through each bar is in accordance with
approved interlocking table.

(iii) The lost motion of a lever, which is locked, shall be such that the
lever block cannot be moved more than 12 mm over the lever
quadrant in the case of locking operated directly by the lever. In the
case of catch handle operated locking, it shall not be possible to raise
the catch handle block more than 10 mm.

(iv) The locking shall be strong, durable and accurate. It shall not be
possible for any mechanical lock to enter a notch other than that for
which it is intended or to force the locking.
(v) The locking in the lever frame shall be effected just at the
commencement of the movement of the lever or the catch handle as
the case may be.

(vi) The release locking shall not be effected before the completion of the
movement of the lever.

(vii) The locked lever shall not be free before the releasing lever has
completed its travel proving thereby that there are no conflicting notches.

(j) Plungers, interlocking bars and locks (dogs) shall be marked as detailed in
Para 12.1.2.

Chapter 12: Installation, Testing & Maintenance of Mechanical Signalling Equipment Page 237 of 535