BOGIES AND SUSPENSION - South Central Railway

CHAPTER 6 – BOGIES AND SUSPENSION
WAGON MAINTENANCE MANUAL
Page 114 of 121
Defective axles, which cannot be repaired, otherwise, required to be replaced.
The axles requiring replacement are pressed out of the wheel centre on a Wheel Press
machine, specially designed for this purpose. After machining new axles to the
required size, wheel centres are pressed on it on the press machine.
After the wheel centre is pressed out with or without tyre, the bore shall be
machined to specified finish on a vertical boring machine. The depth of cut should be
minimum possible, just enough to remove the irregularity of the surface and to ensure
fine finish machined surface. The finish size of the bore should be taken and wheel
seat of the axle should be fine finish machined accordingly to a higher diameter
giving allowance for the required interference fit. The interference should be kept as
0.001 mm per mm, of the dia of the wheel seat/bore of the wheel centre. For example,
for a 180 x 100 mm journal dia of the MG axle, the nominal dia of the wheel seat is
127mm. The required interference fit will be equal to 0.127 mm. The dia of the axle at
the wheel seat should, therefore, be kept 0.127 mm more than the dia of the bore of
the wheel centre. This interference will normally ensure required pressure of pressing
the axle. The prescribed pressure for mounting the wheels and axles shall be as per
IRS specification R-19/93 Pt-I.
While pressing the wheel, care should be exercised to see that the pressing is
stopped at a pre-marked correct location on the inner side of the wheel seat. Wheels
can be mounted on axle with or without tyres. For spoked wheel, if wheel centre and
tyres are separate, wheel centre should be pressed in first and thereafter tyre should be
shrunk. After re-axling, the tyre should be turned on a wheel lathe to remove minor
eccentricity, which is always present. For major eccentricity, which cannot be
removed by tyre turning on a wheel lathe, it should be re-axled.
At the time of re-axling, following points to be ensured :-
i. Before mounting the wheels on axles, carefully clean the wheel seat and
bore of the wheel to remove rust grit, chips and grease.
ii. Coat wheel seat and bore with mixture of basic carbonate white load and
boiled (not raw) linseed oil to avoid scoring of mounting surface.
iii. Keep special care so that wheel-seat and bore and not damaged during
mounting operation.
iv. Mounting press must have dial pressure gauge and a pressure recording
gauge.
v. Mount the wheels centrally on axle at a proper gauge distance.
vi. Recorder must be maintained and kept properly adjusted all the time.
vii. Check wheel mounting and check gauge frequently so that excessive wear
does not allow improper mounting of wheels.
viii. Stamp at the end of the axle box code pressing on pressure and date of
mounting to facilitate tracing of history of the paid of wheels.
ix. After mounting of wheels on axle apply rail gauge at three or more equidistant
points around the circumference to see that wheels are within gauge
limits.