225 OF ENGINEERING KOBMULÆ.
Tractive Fokce that may ke developed in a Locomotive.
S = Square feet of heating surface.
V = Velocity in miles per hour.
g
T = Tractive force in lbs. = 374 — .
Rope Inclines.
W = Weight of one train in tone (vehicles only).
w = Weight of the load (passengers or goods J in tons.
y = Weight of the cable in tons (see “ Ropes ”).
r — Resistance on the level = say -006 at slow speeds.
A = Rate of inclination.
x
V = Velocity in miles per hour.
Hi' = Actual horse-power required, to which should be add ri
25 or 30 per cent, for contingencies, friction of rope, &c.
HP = 6 V £—- — -+ + r(W + w + 2 i/)^for single rope.
HP = 6 V £—+ 2r (W + w + for double rope
(“Tail end ” system).
This formula is based on the assumption that the vehicles
of the ascending train are balanced by those of the descending
train.
t y —i
W + w + - I for endless
---—---+ r (W + w + 4 y) I rope.
San Paulo Railway Incline.
(‘Min. Inst. Civ. Eng.,’ vol. xxx.)
Four lifts, the longest 1| mile long; gradient, 1 tn 9-75;
“ Tail end ’’ system. On the upper half of each lift, 3 rails are
laid; but on the lower half, 2 rails forming a single line ;
half-way ia a crossing siding, with 4 rails about 100 feet long
in the clear, with self-acting switches at the lower end. The
bank top of each lift is on a grade of 1 in 75, and 3 lines of
rails 250 feet long are laid, the centre for down trains. Radii
of curves 30 to 80 chains.
Hopes, steel wire (10 B.W.G.), 6 strand, 4 inches circum-
ference, working load 4 to 4| tong ; life of rope about 2 years.
Pulleys, wrought iron with cast core, 12 inches diameter^
5 to 7 yards apart on curves, 10 yards on straight.
Two engines, 26-inch cylinders, 5 feet stroke, 22 revolutiona
per minute, 30 lbs. boiler pressure.
Horizontal pulleys and winding drums 10 feet diameter.
Special breaks to clip the rails.
Q