PART XV.

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.