Page 445 - IRSEM_Main Book

19.3.6 Testing of Point Machine

(a) Obstruction Test: The point driving rod and the lock connections of the
machine must be so adjusted that with 5 mm thick test piece obstruction
placed between the switch and the stock rail at 150 mm from the toe of the
switch:

(i) The point can not be locked

(ii) The point detector contacts should not assume the position indicating
point closure
(iii) Friction clutch should slip

(b) The Technician shall check whether the current required to operate the
machine in either direction is the same (approximately). The reason for
unbalance, if any, shall be investigated and eliminated.

Note: In general, excessive current indicates the friction due to rubbing of rods
with rods/sleepers, poor packing, lifting of tongue, improper lubrication, dirt/dust
accumulation etc. causing extra load on the machine. The cause to be identified
and rectified duly advising Traffic/P.way departments.

(c) Test the spring in each switch and ensure sufficient spring. It shall not be
too excessive to cause excessive wear on machine part, neither it shall too
less to hold the switch against the stock rail. In either of the case, the point
drive rod shall be adjusted.

(d) Friction clutch where provided shall slip at a value prescribed by the
Manufacturer.

(e) Badly worn-out pins shall be replaced; the holes shall be reamed out and
fitted with a oversized pin. Split pins where provided shall be properly split
out.

(f) Voltage and current shall be checked periodically at the motor terminals,
as per Annexure: 19-MS2. This will indicate any undue friction on the
points or improperly fastened terminals at cable terminations.

(g) Cable and wire insulation and continuity tests shall be done.

(h) The essential requirement for interlocking of point shall be periodically
checked.

(i) It shall be ensured that during obstruction in the point, the feed to point is
automatically disconnected or friction clutch is tripped on overload described
by manufacturer and reconnects only when a fresh operation is done.
Where sequential operation of point machine is done, the maximum time
before disconnection may not exceed to 3.5 times the normal operating
time of one machine.
(j) Each sectional JE/SSE (Signal) shall test the operating values of the
machine and adjustments of the machine by obstruction test every month.
The Sectional incharge of the section shall carry out these tests once in
three months.

Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 393 of 535