802

THE COLLIERY GUARDIAN.

October 27, 1916.

with the gate at the lower end, so designed that the
weight of the coal cannot force it open.

Bumpers.

Radial faced centre bumpens permit of stronger con-
struction than the double, and distribute forces, inci-
dent to bumping, over the entire car bottom, thus
reducing the tendency to twist the car out of shape. .
Double bumpers transfer such forces along the sides,
thus tending to jar the bolts loose, and distort the car.

The bumpers should overhang sufficiently to prevent
the corners of the cars from interfering on the sharpest
curves, and should be so designed that there can be
no risk of their riding an opposing bumper, not even
when pushing a trip of loads around a curve with an
empty near the motor.

Fig. 3.—End Elevation of Solid Car.

■O£

Fig 5

040

& 1

?*?'

0 H £

> J

nZ

Fig. 4.—End Elevation of Gate Car.

A good coupling must permit of the connecting up of
the cars, when either jammed or free on curve or
tangent. The coupling should be done quickly, easily,
without risk of pinching the fingers, and with cer-
tainty of a positive hold. It must not hang down over
the bumpers so as to constitute the danger of fouling
in frogs or switches. It must not permit of more waste
play than is absolutely necessary to enable a connection
being made on a curve; every inch of waste play per
car in a trip of 30 or 40 is the cause of heavy jerking
both in starting and stopping, which is very hard on the
cars, motor, and power plant. Both the coupling and
the pin should be positively fastened to the car (as in
fig. 5), in such a way that neither can cause trouble
nor become lost.

Spring draw-head couplers similar to those used in
railroad practice are expensive, heavy, require a steel
bottom, and cannot be recommended. Automatic
couplers work satisfactorily only on easy curves, where
the tracks are in good condition, and where changes in
grades are gradual. They also require a steel bottom
car and are very expensive. Mine tracks are seldom
graded in rooms or in fresh development work, and
changes in grade are often abrupt, requiring a wide
range of elasticity in a coupling to take care of the
vertical and transverse movements at the end of the
car; the clearance permitted by an automatic coupler is
hardly sufficient. Three link couplings are satisfactory
only with double bumper cars. With such bumpers,
and a hooked or pin drawbar, rapid connections are
made. They drag when not hung to the car-end, and
like lift gates the avoidance of wrecks becomes
dependent on the human element. With centre bumpers
they interfere, and with motor gathering are a general
nuisance. Hooked draw-bars require 2 in. more play
than any other type to make a coupling, are not positive,
and therefore should be condemned.

The single link coupling, forming part of a spring
drawbar and engaging with the pin on the opposite car,
offers the best design. It has but one disadvantage : the
link projects for 8 or 9 in. behind the car. Of course, it
may easily be pushed to either side and left lying on the
bumper; the clearances must be such, particularly in
shaft mines, that if this is overlooked trouble will not
result. The coupling shown in fig. 1 rides on a 2 in. by
| in. bat bar, which keeps it from interfering with the
opposing bumper, and avoids the risk of fingers being
hurt.

The hole in the bumper for the pin accommodation
should be funnelled at the bottom to avoid wet slack
clogging it up. Pins should have a good handle; often
considerable force is needed to dislodge or set them. A
chain connecting the pin to the car is a make-shift, and,
like all flimsy material, is to be condemned.

Drawbars (Figs. 1 and 2).

With rigid connections from 40 to 100 per cent, more
power is required to start a trip than to keep it moving.

A motor’s capacity is limited by the load it can start.
For effective work a spring pull is imperative.
It protects both car and motor, and increases the
capacity of the latter at least 50 per cent, from the fact
that the spring, acting as an equaliser, eliminates a dead
pull of the gross weight. The drawbar bolted to the car
bottom with the spring link at the closed end of the car
(as shown in fig. 1) is the best form of construction.
Cans are invariably sent to the face with the closed end
inbye. Loaders thus throw their coal towards the gate
end, which leaves the spring protected and at a point
where it does not interfere between the car bumper and
the dump hopper when in the dumping position.

Trucks.

Loose wheels are preferable to tight ones. The latter
require a very short wheel base for sharp curves; their
axles can be straightened only with the greatest diffi-
culty, and in no way do they offer points of superiority
over a w’ell-designed loose wheel.

The smaller the diameter of a wheel, the greater the
car’s capacity for a given height of box, and the lower
the centre of gravity of the moving mass, thus reducing
a tendency of the car to jump. On the other hand, the
larger the wheel and the greater the ratio of wheel to
■axle diameter, the lower the frictional resistance and
greater the strength. Experience only can dictate the
happy medium.

The friction of a good roller-oearing wheel should run
from 20 to 251b. per ton of load when starting the trip,
and 10 to 12 lb. per load when it is in motion on a level
grade. Bushed wheels will require approximately double
these figures. The rolling stock is thus ensured of a
longer life, and the generators are not called upon to do
the same amount of work. A roller bearing wheel uses
non-fluid grease. Thus the tracks are kept free from the
excess oils which leak through many other types, causing
trouble with motors, and unnecessary waste.

The life of an iron wheel depends on its diameter,
hardness of hub, toughness of spokes and depth of chill.
It should be made up of a minimum number of parts,
and should be grease tight. Where the axle is allowed
to protrude through the hub, grease can work out and
grit work in. It should be free of washers, felt, springs,
removable caps and other parts that so easily become
loose, lost, leaky, and inefficient. It should not wear in
the hub nor break at the flanges—the cause of many a
wreck. Another point—treads must have sufficient
width and flanges of the proper form that, when taking
curves with rails spread from £in. to lin., the danger
of track jumping will be reduced to a minimum.

Before committing oneself to a roller-bearing truck a
careful study of the Hadfield wheel is warranted. This
is a self-oiling, toughened cast-steel wheel, exceptionally
strong and very light. A set of 16 in. wheels on 2|in.
axles, with a 42 in. gauge, weighs 4551b., as against
880 for the roller bearing. This wheel also uses a non-
fluid grease, is capless, has a long life, holds to a rough
or uneven rail better than the iron, and will not break.
The wheel base should be from a quarter to a third of
the length of the car body. A wide base lends stability
to the bottom, and keeps the car from jumping off the
track. It is harder to re-rail a long wheel-base car bhat
is derailed, and it requires easier curves for its accom-
modation; consequently, here, as with the diameter of
wheels, a practical medium must be chosen.

Fig. 6.—Brake with Shoes tending to Bind.

Fig. 7.—Band Brake.

A good truck journal should be of metal tough enough
to resist the tendency to funnel; should be a one piece
casting; should protect the wheel from grit; should
have a broad bearing on the car bottom, two and one-
half times the axle diameter, and be removed easily.
Outside journals are expensive, and do not readily lend
themselves to mine car construction. The rigid type
has nothing to commend it, and the spring pedestal only
the advantages of holding the wheels to the track and
permitting loose wheels to take curves with greater
ease. These features are better cared for by the wooden
and medium base. Each truck should be fastened
across the car bottom by a channel and the two channels
fastened to one another by axle straps. Axles are then
held true, and the running strains absorbed.

Brakes (Figs. 6, 7, and 8).

The brake should lock each wheel to -which it is
applied; should be simple in design; easily adjusted;
require no extra clearance; should not reduce the capa-
city of the car; should not be exposed to any damage;
and, lastly, should have removable shoes so suspended
that they tend to fall clear of the wheel when released
(as in fig. 1.).

The brake lever should be on the left side of the rear
end of the car, and be so arranged that a man while
standing or running may balance himself against the car
side with his left hand and pull outwardly with his
right. The movement should never be up nor down,
nor an inward push. A trip-maker can hurt himself
most easily on either an up or down movement, and is
almost certain to be maimed if he slips when pushing
on a lever between moving cars. The lever should be
near the edge, and should have a short throw with an
eccentric travel forcing the handle to move in a hori-
zontal path; not through an arc rising towards the roof
with the danger of interference in low places.

With motor haulage, conditions seldom arise where it
is necessary to apply a brake to more than two wheels.
On a properly designed shaft bottom or tipple brakes are
not required. In rooms where cars are handled by the
loader it is often desirable to have a brake (as shown in
fig. 7), on one wheel to avoid spragging.

Check Hooks.

The check hook should go on the front end of car, and
be close to the right hand top side, if horn or rotary
dumps are in use, or at the centre if these be self-
dumping cages. Checks should be hooked on the out-.

' ii

1 'I

II u.---

II
II
|l Levs
H APPl-lto

Fig. 8.—Brake Lever.

side. With a properly designed hook, it is just as diffi-
cult to steal from the outside as from the inside. An
outside check tends towards cleaner coal; foremen,
haulage men, and weighers are in touch with the loads,
and an unusual one is more apt to be noted and the
check number taken. Close to the hook should be the
car number in large white figures. By keeping record
of these numbers loaders can protect themselves against
their checks being tampered with or lost.

Clearance.

Mines shipping domestic coal require a greater clear-
ance between top of the car and the roof than those
supplying a steam or coke market. For domestic trade,
when the seams are 60 in. or more in thickness, a car
should not exceed 40 in. in height. The loader will lift
large lumps to that height rather than reach for his pick
and thereby lose time in breaking them. The length of
a car is governed by shaft clearances and track curves,
rather than by conditions at the face. With a good
roof, loaders invariably prefer two cars at a time. This
proves that a throw of 12 to 14 ft. is not excessive.
Where practicable, it is well to have the car box long
enough to hold mine props; this materially simplifies the
delivery of timber to the face.

Spare Supplies.

In placing orders for new car equipment it is well to
stock the following supplies for each 100 cars contracted
for : 12 links, 24 pins, 6 drawbar springs, 6 drawbars, 6
bottom side plates, 6 journals, 6 wheels, 48 rollers, with
roller bearing wheels, 12 bushings or cages, with roller
bearing wheels, 6 locking pins, with roller bearing
wheels, 6 brake shoes, 1 barrel car paint, 1 4001b. barrel
roller bearing grease, and 1 large capacity grease gun.
Cars for the transportation of rails and timber, those
fitted with hose, reel, and pump for fire fighting, the
sand car, the rescue car, and also water-tank and tool
cars, should be modelled after the same design.

Life and Costs.

The life of a wooden car is about three years, and of a
steel car from eight to ten years.

The cost of a two-ton steel box is about double that of
a wooden box, but the fixed charges are slightly in
favour of the steel car. The steel body is tight at the
joints, permits but little leakage; stands up to abrasion:
permits larger capacities, greater speeds, and will
undergo shocks that would quickly send a wooden car to
the scrap heap.

An amendment of the Coal Mines Regulation Act is being
prepared in Australia which will evoke protest from the pro-
prietors. A deputation representing the Australian Colliery
Employees’ Federation submitted to the Minister for Mines
a number of provisions and amendments they want. Among
these are bathing accommodation at the mines, so that the
miners can clean and change before leaving the mine: sani-
tary arrangements in the mines: an eight hours day for all
employees; abolition of night work, except where necessary
for development, and then the shift to be restricted to six
hours; testing of safety lamps (they want a certain candle-
power as standard); amendment of Special Rule 195. An
amendment is wanted restricting the power of dismissal.
The Minister promised that these requests would be granted.