Page 219 - The Tribology Handbook

Wheels, rails and tyres B11

Table 11.2 The effect of warious factors on load capacity
Material Other
Sp'ted [ V) Elevated temp. Wheel dia. InfEation pressure Wear
composition factors
Steel tyres Small effect only Not important See Figure 11.4 Hardened steels Not applicable Wear will reduce
on steel except in the or increased the section
rails extreme. High 'carbon modulus and
temperatures equivalent' hence the load
generated during content capacity of the
braking can increase load rail
cause thermal capacity
fatigue of tyre
treads
Pneumatic Thle effect of Load capacity See Figure 1 1.1. Load capacity Inflation pressure Within the legal
rubber speed on load must be limited Outside increases with is a vital factor limits wear has
tyres capacity can to prevent diameter and tyre ply rating. affecting load no effect
be reduced by excessive tread width Materials with capacity, see provided the
increasing temperature rise. can vary low internal Figure 1 1.1 tyre has been
inflation Maximum widely for a friction are and other correctly used
pressure; see temperature particular rim more suitable columns and is
Figure 1 1.5 120°C. Increased size for consistent undamaged
inflation high-speed use
pressure reduces
running
temperature

OUTSIDE DIAMETER OF WHEEL, in
7 10 15 20 24 36 100

105
OVERHEAD CRANE
(FLAT HEADED RAIL)

1 o5 RADIUS HEADED RAIL)
L
P
1-
104
2
CT LT
W FOR INDUSTRIAL w
a Q
2- >
t k
0 0
,Q 104 2
Q 6
u 0
Q D
s 103 9
Q Q

103 1 ---I- PNEUMATIC TYRED COMMERCIAL VEHICLE WHEELS I
-
PNEUMATIC TYRED PASSENGER VEHICLE WHEELS, 1.25 bars
AND 2.5 bars INFLATION PRESSURES
I"
0.2 0.5 1 2
OUTSIDE DIAMETER OF WHEEL, rn
(RIM DIAMETER OF WHEELS WITH PNEUMATIC TYRES)
Figure 11.3 Load capacity is plotted against wheelsize for typical UK operating conditions. Steel rail material to
IS0 5003 (0.45% C 7 % Mn). Steel tyre material to BS 970 ft 2 7988. Pneumatic tyres are of cross ply construction
to IS0 4251 and 4223. Solid rubber tyres are to American Tyre and Rim Association formula taking width and
thickness as $ and & outside diameter respectively
B11.3