The Providence news. (Providence [R.I.]) 1891-1906, 1901-04-17
NO WHEEL. NO CAR

The manufacturers of carwheeis have
kept pace with the vast strides MADE IN
All other departments of street railway car
construction. Twenty years ago the aver
age horsecar wheel weighed about zoV
hounds. and was made exclusively OF
good grade Of chilled gray iron but IN
1890 with the advent of electric cars
with their heavy trucks, motors and bod
los the whcelmakers saw that "A radical
change had TO be made in the weight ma
terlal and design OF wheels for the cars
AFTER some experimenting they adopted
AS standard the 3O-inch wheel ol "V
pounds aud the 33-inch wheel or dbo ana
sqo mounds the same being made up IN
snokes ana solid plates Of steamcar de-
sign. AS a rule they pushed the SAFE OF
th,, sso-pound wheel.
rhe average agl-pound wheel OF chilled
cast iron costs "a bout $50. and VIII MAKE
an an average $4,000 miles, while steer
wheel costs about double and VIII inake
about double the mileage The steel wheeS
arI made np h three WAYS. one ~
solid all-steel casting; another Is hish
carbon steel tread shrunk on cast-lroh
wheel. and last and what is supposed 10
be the best Is a sectional chrome steer
wheel. ga which the hub Is hrst cast
around tho spokcs. the rim bcing cast on
last AS the hub and iron slowly con-
tract the spokes are held in steel grasp.
which makes the wheel even stronger
than an all-stccl casting.
The iron wheels are made from soon
grade of gray iron, with a percentage OF
manganese added, and are cast IN molluS
containing Strcf-rf1iil pfutrs7 or n nu11oW
steel rim containing cold water, piaceu
against the tread Of the wheel In the
pouring process the hot metal coming IN
contact with the chill plates. or water
pockets, causes the tread and rim 10 cooi
and contract very rapidly This results IN
"a very hard surface. extending back into
the wheel from three-quarters OF an men
90 one inch aud a half As soon as the
wheels have hardened enough IN the
moulds 10 be handled they are picked up
by travelling cranes and conveyed rel
hot 10 the annealing pits, where they
gradually cool of. This takes about sew
en- DAYS, the object aimed at being "A
gradual shrinkage, in which the wheel
loses none Of it's symmetry and does NOT
check. which would happen IL II were AL
lowed 10 cool as ordinary iron castings
are
When ready for mounting they are
bored out TO about l-l0O0 of an inch OF
the size OF the axle, and are pressed on
AT about thirty-hve tons pressure by
nAhlhuAst RAM ~ iVNfi pt'fN'fNAf A''N'N-A
ing possibility of looseness In the fu-
ture; whereas "A higher pressure Is liable
10 burst the wheel AT the hub.
ON any well organized street railway
system the inspection OF wheels is a very
important duty, as the breaking OF de-
fective wheel at critical moment, such
as going over bridges and elevated tres
ties. or coming down curves, may lead To
disaster not only 90 the passenger. but.
financially. 10 the company, from damage
suits. resulting from such accident.
lne use OF heavy equipments has given
the mechanical department of street rail-
way companies new problem TO handle
the fiat or skidded wheel. The average
weight Of n trolley car is seventeen tons.
When the rails ARE icy or greasy II Is inn
possible TO bring the cars, with their
great momentum, to a sudden stop. Even
though the wheels are locked they Will
slide fifteen or twenty feet. This friction
wears down the surface Of the wheels.and
sand on the track, acting like emery.
helps TO aggravatc the trouble.
Wheels when so fiatted are taken out
in pairs and put into a grinding machine
and revolved In direction opposite to
that of the emery or corundum wheels
OF the machine. which revolve az "A very
higa speed. This process of grinding II
kept up until both wheels are ground
down to an even size and the fiat spot or
spots have disappeared. but in this pro-
cess the life OF the wheel has been great
~ reduced, AS the chilled surface ground
of represented just so many miles Of
travel