BOGIES AND SUSPENSION - South Central Railway

CHAPTER 6 – BOGIES AND SUSPENSION
WAGON MAINTENANCE MANUAL
Page 99 of 121
the bath must not exceed 45 o C under any circumstances because above this
temperature, some of the valuable hardening elements like antimony and copper are
partly lost by oxidation as dross and hard oxide inclusions cause excessive wear of the
journal. Over heating also cause brittleness and excessive contraction. Remove the
bearing after the metal is set and allow it to cool in air. However, a minimum time of
5 minutes must be given after pouring of white metal to enable the white metal to
solidify properly.
Each metalled bearing should be tested for soundness by giving the ‘ringing
test’ to a bearing suitably suspended. A perfectly metalled bearing with satisfactory
bonding would give a ring more or less similar to the ring of the shell prior to its
metalling. A dull sound would indicate discontinuity such as porosity, improper
adhesion, loose spots and general unsoundness. At least 1 percent of the daily output
of metalled brasses should be given a destructive test, preferably the chip test. This
involves the removing of a portion of the white metal from the shell with a chisel and
hammer. When properly bonded, difficulty will be experienced in doing this and the
lining will torn away from the shell leaving a rough surface where some of the white
metal will be still adhering to the shell. If on the other hand, bonding is not
satisfactorily done, the white metal will come away from the shell quite easily,
leaving a dull grey surface.
The temperature ranges, although indicated earlier in these instructions are
summarized below and must be adhered to :-
Demetalling bath 400 o C to 450 o C
Caustic Bath 60 o C to 70 o C
Pre-heating prior to tinning 200 o C to 250 o C
Tinning bath 280 o C to 300 o C
Pre-heating of chill 150 o C to 175 o C
White metal bath 350 o C to 400 o C
White metal pouring 350 o C to 380 o C
Frequent checking of the temperatures of various baths is necessary. Pyrometers
are likely to go out of commission or give faulty readings a bit too frequently.
Portable thermometers must therefore be provide at each white metalling point to
check on the accuracy of the pyrometers and also for regular use in the event of
pyrometers going out of commission temporarily.
605 T. MAINTENANCE INSTRUCTIONS FOR FRLP
FRLPs may be procured/supplied in :
a) Dry condition
b) Pre-oiled condition