BOGIES AND SUSPENSION - South Central Railway

CHAPTER 6 – BOGIES AND SUSPENSION
WAGON MAINTENANCE MANUAL
Page 60 of 121
ix. Corrosion:- Corrosion occurs either locally or throughout the section in the
form of small shallow pits (pitting corrosion). These act as stress raisers under
alternating stress conditions during service. Such plates should be rejected
during repair/manufacture. If springs with corroded plates are noticed in
service, they should be replaced.
x. Other causes: The following causes may lead to either fatigue crack
formation or sudden fracture (a) uneven loading of wagons, (b) uneven
bearing of pins on spring eyes due to use of worn out pins, (c) lateral shifting
of spring plates due to slackness of buckle.
Wagons unevenly loaded should not be allowed to run in service.
Worn out pins should be replaced. Spring with shifted plates beyond limit
should be replaced.
605 E. CAUSES FOR FAILURE OF BUCKLE
The buckle may fail for following reasons. Action to be taken has been
indicated against each item:
i. Wrong materials: Correct material of buckle should be used.
ii. Poor welding: When buckles are made by bending flat to shape and are
welded at the ends, welding should be sound and without defects.
iii. Overheating: At the time of heating for buckling ensure that they do not get
overheated or over soaked both of which will cause brittleness in the steel.
iv. Larger buckle: (a) Too large a buckle compared to the cross sectional
dimensions of the spring assembly results in folds being formed on the buckle
especially at the corners which may open up immediately after or in service
(b) Rigid inspection should be done while manufacturing. Buckles with such
defects should be rejected.
v. Cold buckling: (a) Ensure correct temperature during buckling since cold
working gives rise to crack/residual stresses resulting in cracking up of the
buckle immediately after or during service. Insufficient buckling pressure or
temperature can also cause the buckle to shift. (b) Ensure rigid inspection
during manufacture/repair.
vi. Sharp corners: The edges of the packing or keyplates and the bottom plates
should be grounded to a smooth radius. It prevents the formation of sharp
corners in the buckle that may result in tearing of buckle or act as stress raiser
in service.
vii. Excessive nip on plate: Ensure that excessive nip between plates is not
provided to prevent building up of additional tensile stresses tending to crack
the buckle either during manufacture or in service.