22G Molesworth’s pocket-book
Continuous Railway Breaks.
W = Weight of train.
V = Velocity in fe(t per second.
D = Distance travelled before stopping.
R = Mean retarding force.
H = Height corresponding to velocity V.
F = Accumulated work.
g — Gravity, say 32 • 2.
V‘2 W V2
R = FD; H = —; F= -------------; = -0155 WV«.
29 29
Trains about 200 tons.
Train resistance 9 lbs. per ton, or '4 per cent, of gross weight.
Friction of engine and tender, ) •
not reckoning curves, winds, >• 62 „ „
or gradients...............)
Retirding influences, average 7-62 „ „
Distance of stopping at 30 miles per hour 470 feet.
>> 45 „ „ 1000 „
» » 60 „ „ 1870 „
776 to 1100 feet 'n 1th sand.
844 „ 16^0 „ without „
Foot-tons per second .. .. 1017 „ 6“5 „with
96-1 „ 491 „ without
Tender and break van’s break 2 • 36 per cent.
Coefficient of Friction, Cast Irox on Steel.
Velocity,
Miles per
hour.
From commencement of Experiment.
5 Seconds. 10 Seconds, I Ifi Seconds. 20 Seconds
2
6-8
13-6
17
20-4
27-3
30-7
34-1
37’5
40-9
47-7
•250
•242
•210
■2G5
•182
•171
•163
•153
•152
■ 141 I
•132 I
•193
•157
•152
■130
•107
•C96
•093
■080
— -no
■133 *116
•119 "081
•099 —
•083 -069
•070 —
•C99
•«72
By Galton’s experiments with cast-iron blocks on steel
tires, coefficient of friction varied from "A42 at io miles, to
• 1 lö at 50 miles per hour.