Page 62 - IRSEM_Main Book

4.6 CARRIAGE AND WAGON Related Items:
(a) Variation in wheel diameter within the wheels of same axle shall not be more than 0.5
mm for both goods and coaching stocks.
 Difference of wheel diameter between wheels of same axle - within 0.5 mm.
 Difference of wheel diameter between wheels of two adjacent axles of the same
trolley: Goods: within 13 mm Coaching: within 5 mm.
 Difference of wheel diameter between wheels of different trolleys of a bogie: Goods:
within 25 mm Coaching: within 13 mm.
(Note: Due to difference in wheel diameter, there will be angular motion of the wheels.
Wheel with lesser diameter may have tendency to mount over rails and derail whereas wheel
with higher diameter will cause increased wear and tear)
(a) Sharp Flange
 Flange of the wheel sometimes wears to form a knife edge which becomes unsafe when
radius of the flange at the tip is less than 5mm.
 A wheel with sharp flange has biting action particularly while negotiating curves.
 Sharp flange may split open a slightly gaping point.
 While travelling in facing direction it may even mount the tongue rail.
 Rejection limit for flange tip radius is less than 5 mm for BG/MG
(c ) Thin Flange
 Flange becomes thin by wear and tear of the tyre and flange and is considered unsafe
when it becomes less than 16 mm.
 This increases clearance between wheel flange and rail, which in turn increases the
derailment proneness.
 Oscillations increase due to greater play between wheel set and track resulting in
greater instability of the vehicles
 Rejection limit is 16 mm BG/MG measured at 13 mm from the flange tip.
 It also damages tongue rails due to more play.
(d) Flat Tyre /Skidded wheel
 It may occur due to continuous brake binding, skidding, brake block tilting and
jamming against the tyre.
 Flat tyres cause passenger discomfort and may become unsafe.
 Flat tyre causes greater hammering action on the rail and rail fractures may take place.
(e) Deep Flange
 Deep Flange may hit track fittings like fishplate joints, lock bars, point and distance
blocks.
 A deep flange tends to ride on fishplate and distance or check blocks and damage the
track, particularly if there is vertical wear on railhead.
 Rejection limit in depth of flange greater than 35 mm (BG), 32 mm (MG) measured at
63.5 for BG and 57 mm for MG away from back of wheel.
(f) False Flange/Hollow Tyre.
 Excessively worn-out tyre on tread is a hollow tyre. Hollow tyres develop a false
flange. The false flange formed may force open the switches when the vehicle runs
in the trailing direction on points and crossing.
 False flange can be dangerous at the wings of crossing as it may ride over the wing
rail, lifting the wheels and creating conditions favourable to derailment.
 If the hollowness is more then it results in difference in wheel diameter and the
wheel may ride over the rails.

Chapter 3: Duties Of Signal Supervisors And Technical Staff Page 40 of 535