BOGIES AND SUSPENSION - South Central Railway

CHAPTER 6 – BOGIES AND SUSPENSION
WAGON MAINTENANCE MANUAL
Page 82 of 121
The step sizes of brass cater for all the journals which have dimensions
between the new and condemning limit. The 3 step sizes are known as A, B & C. On
‘A’ size brass, the diameter of the while metal shell is kept 3 mm. more than the new
journal as well as on the journals having diameters less upto 3 mm. from the new
axle. Similarly, the length of the bearing is kept 3 mm less for MG & 5 mm less for
BG than the length of the new journal. These shells can be used for journal length,
which are even 2 mm. more than the new. When the length and dia. of the journal
crosses these limits ‘B’ size bearing brass is used. After certain stage, ‘C’ size bearing
is used. Thereafter the journal is condemned. Use of step size brasses is tabulated
below:-
S.
No.
Particulars Nominal
Size
1. Journal Dia mm
D
2. Bearing
diameter
3. Length of
Journal
4. Length of
Bearing
5. Shell Height at
Crown
6. Length of
Collar (Outer)
Depth of
Anchor groove
(outer)
Mm
D to (D-3)
A B C
Mm
Below (D-3) to
(D-8) for MG
& (L-6) for BG
BG D+2 D+2 D-1
MG D+2 D+2 D-2
BG L L Minimum L+2Minimum
MG L L Minimum L+3Minimum
BG L-5 L-5 L-3
L-3 L-3 L
H H H+2 H+4
I
L
I
D
I +3
D+3
The composition of bronze shell and while metal is as under:-
Bronze Shell
Lead 4 to 6%
Tin 4 to 6 %
Zinc 4 to 6%
Antimony 0.3% (Max.)
Phosphorous 0.05% (Max)
Copper Balance
White Metal
Antimony 14 to 16%
Tin 4.5 to 5.5%
Copper 0.3 to 0.7%
Lead Balance
mm
Below (D-8) for
MG & (D-6) for
BG to condemn-ing
size.
D-4
D-6
L+5 Minimum
L+6 minimum
L
L+3
I +6
D+6