MISCELLANEOUS.
QUESTION 325. _What is the sand-box, V, plates I and II for, and how is
it constructed?_
_Answer_. It is intended to carry a supply of dry sand, which is
scattered on the rails in front of the driving-wheels when the latter
are liable to slip. This is done by two pipes, _e′, e′_, plate I, one
on each side of the engine. They lead from the sand-box to within a few
inches of the rail. At the upper end and inside the sand-box they each
have a valve which is operated by a lever which is connected to the cab
by a rod which enables the locomotive runner to open or close the valve
at pleasure.
The sand-box is usually made of sheet iron with a cast iron base, and a
top of a more or less ornamental design. It also has an opening on top
through which the sand is supplied to the box. This opening has a loose
cover to exclude rain and dirt from the sand. The sand-box is usually
located on top of the boiler in front of the front driving-wheels.
QUESTION 326. _What is the bell U for?_
_Answer_. It is used for giving signals of the starting or approach of
the engine. It also is located on top of the boiler and is usually hung
on a cast iron frame and rung with a rope connecting it with the cab.
QUESTION 327. _What is the weight of an ordinary locomotive bell?_
_Answer_. From 50 to 100 pounds.
QUESTION 328. _What is a locomotive head-light?_
_Answer_. It is a large lamp, _T_, plates I and II, placed in front of
the locomotive to signal its approach at night and also to illuminate
the track for the locomotive runner.
[Illustration:
_Fig. 198._
Scale 1¹⁄₂ in. = 1 foot.]
QUESTION 329. _How is a head-light constructed?_
_Answer_. The lamp has what is called an Argand burner; that is, a
burner with a hollow cylindrical wick, through the centre of which a
current of air circulates, which thus supplies the flame with a larger
quantity of air than is possible if the latter can come in contact with
the former only from the outside. The result is that the combustion
is much more brilliant than with ordinary burners. In order to throw
all the light on the track the burner is placed inside of a concave
reflector, _a b c_, fig. 198, which is of a _parabolic_ form. One of
the peculiarities of this form of reflector is that if a light is
placed in its focus _f_ the rays will be reflected from its surface
in parallel lines. Thus, let _a b c_, fig. 198, represent a section
of such a reflector. Now, if a light be placed in the focus _f_ the
rays will strike against the reflector, be thrown in the direction of
the dotted lines _f 1 x, f 2 x ... f 9 x_, etc., and thus be thrown
directly in front of the engine. The reflectors are usually made of
copper and plated with silver.
The lamps and reflectors for head-lights are inclosed in a rectangular
case which is supported on two brackets bolted to the front of the
smoke-box. On these brackets a wooden shelf is fastened on which the
head-light rests.
QUESTION 330. _What are the running-boards and hand-rails?_
_Answer_. The _running-boards_ are planks, _i i_, plate I, placed on
each side of the boiler to enable the locomotive runner or fireman to
go from the cab to the front end of the engine when it is running. The
hand-rails, _m m′ m′_, are brass or iron pipes attached to the top of
the boiler and extending from the cab to the smoke-box, and are placed
there, as their name indicates, to support or for a hand-hold for
persons on the running-board.
QUESTION 331. _What provision is made for removing from the track
such obstacles as cattle or fallen rocks, which may be in front of
locomotives?_
_Answer_. What is called a _cow-catcher_ or _pilot_, _S_, plates I
and II, is attached to the front of the locomotive. This is usually
made of wood, and consists of a triangular frame at the bottom which
is supported about four inches above the tops of the rails. Straight
pieces of wood of about 2¹⁄₂ × 4 inches section are fastened to
this frame and also to a horizontal piece which is bolted to the
bumper-timber _E′_. These pieces arranged in this way and only a few
inches apart give to the cow-catcher a peculiar curved form somewhat
resembling that of the mould-board of a plow, which is very well
adapted for throwing any obstacles from the track. Sometimes these
pieces are placed horizontally instead of being inclined up and
down. Cow-catchers are also in some cases made of round iron bars or
angle iron. They are always bolted securely to the bumper-timber and
strengthened by strong iron braces attached to the bottom frame at the
front and back. These braces are usually fastened at the other end to
the bumper-timber, but are sometimes attached to the bed-plates of the
cylinder.
There is also usually a strong _pushing-bar_ attached with a bolt and
hinged joint to the bumper-timber. This is shown in plates II and III
in the position it occupies when not in use. It is used in pushing
cars, as very often there is not room for the pilot under the end of
the car. In using it is raised up, and the front end is then coupled to
the draw-head of the car.
[Illustration:
_Fig. 199._]
QUESTION 332. _What is the foot-board or foot-plate of a locomotive?_
_Answer_. It is a wrought or cast iron plate which extends across and
rests upon the two frames at the back part of the locomotive and behind
the boiler, and on which the locomotive runner and fireman stand. It
also unites the two frames very securely, and furnishes an attachment
for the draw-bar. The foot-board is often made much heavier than is
necessary for strength, in order to increase the weight, and thus the
adhesion, on the driving-wheels. It is a fact often not suspected
that any weight placed on the back end of an ordinary locomotive will
increase the load on the driving-wheels by an amount considerably
greater than that of the weight itself. The reason of this is that the
locomotive rests on the centre of the truck and the centres of the
equalizers, and therefore the weight, if applied to the back end of the
engine, gains considerable leverage. This will be clear if we take a
beam, _A B_, and rest it on two supports, _m_ and _n_, fig. 199. If now
we put a weight _W_ on the end, overhanging the point of support, the
weight which will rest on _n_ will be equal to that of _W_ multiplied
by its distance _C_ from _m_ and divided by the distance _D_ between
_m_ and _n_. Thus if a foot-board weighs 1,000 pounds, and its centre
of gravity is 5¹⁄₂ feet behind the centre of the equalizer, and the
latter 14 feet from the centre of the truck, then the weight thrown on
the driving-wheels will be equal to
1,000 × 19¹⁄₂
------------- = 1,393 pounds.
14
The same thing is of course true of any other weight placed on the back
end of the engine.
QUESTION 333. _What are the “wheel-guards” of a locomotive?_
_Answer_. They are sheet iron covers over the upper half of the
periphery or tread of the wheels, and are placed there to protect the
engine from the dirt and mud which adhere to the wheels and are then
thrown off on the machinery by the centrifugal force.
QUESTION 334. _What are “check” or “safety chains?”_
_Answer_. There are two kinds of such chains, the one attached to
the trucks and frames of the locomotive and the tender. The object
of these chains is to prevent the trucks from turning around and
getting crosswise of the track if the trucks should leave the rails.
The other kind of safety chains connects the engine to the tender,
so that, in case the draw-bar or coupling-pins should break, the two
will not separate. Great care should be exercised to attach the truck
chains so as to be strong enough to resist the strains to which they
will be subjected in case the trucks run off the track. The grossest
carelessness and ignorance are often shown in the construction of these
parts.