Page 444 - IRSEM_Main Book

Initial Adjustment of Point Machine

19.3.3 Adjustment of Driving Rod

The points shall be adjusted by operating the machine first by hand cranking.
The insertion of hand crank should disconnect the power supply to the machine.
When the machine has been fastened down, the throw bar connections shall
be set up and the point machine hand cranked to one end of the stroke
positioning the locking blades so as to allow the appropriate locking dog to
pass through notches. The closed switch shall be adjusted to just in contact
with the stock rail. Then the connections shall be tightened further by 2 mm to
3.5 mm to impart a springing action to the tongue rail. The machine should be
hand cranked to the opposite end of the stroke and the setting repeated for
the other switch.

Note: it is recommended that adjustment for driving rod and lock rod shall be done
for the close switch nearest to the point machine first.

19.3.4 Adjustment of Detector Contacts

The machine shall be hand cranked to the end of the stroke to close the
tongue rail. Insert 1.6 mm test piece between stock rail and switch rail at 150
mm from toe of the switch and operate the point. Ensure detector contacts just
make. A test gauge of 3.25 mm shall be inserted between the switch rail and
stock rail at a distance of 150 mm from the toe of the switch. The detector
connection of the closed switch shall be adjusted till the appropriate detector
contacts are just broken. The same shall be repeated at the other end of the
stroke. All the relevant nuts shall be tightened.

Note: Where lock slide is provided in the machine, during switch detector adjustment

the test shall first be done with fictitious locking. After completing the above test,
same test be repeated with machine properly locked.

19.3.5 Adjustment of Friction Clutch

(a) When IRS rotary type electric point machine under obstruction test draws
less than 1.75 times the normal operating current, machine needs to be
checked for proper functioning at site.

(b) 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 and

(iii) Friction clutch should slip.

Chapter 19: Installation, Testing & Maintenance of Signalling Equipment Page 392 of 535