In case of a broken front cylinder head, disconnect the radius rod as described above and clamp the valve stem with the valve covering the ports; remove the cylinder cock from the back end of the cylinder to relieve the compression there and proceed on one side, lubricating the piston on the disabled side through the front end of the cylinder. In case of a back cylinder head being broken, proceed in the same manner as described for a bent piston rod.

75. Q.-How should an engine equipped with the Walschaert gear be disconnected in case of a broken crosshead arm, a broken lap and lead lever, a lap and lead connection rod or lifting arm?

A. On some types of engines equipped with the Walschaert valve gear in case of a broken crosshead arm, lap and lead lever or lap and lead connector the lap and lead lever can be removed and the radius rod connected direct to the valve stem. This will give a travel of the valve equal to the full travel less the lap and lead, and the engine can be handled on both sides. If this connection cannot be made, the only thing left to do is to put the engine on one side, remove the broken parts, either crosshead arm, lap and lead lever or lap and lead connector, and block the back end of the radius rod in the center of the link and disconnect the lifting rod on that side. Block the valve so as to slightly open the back steam port and proceed on one side.

In case of a broken lifting arm place the reverse lever in a position where the engine would start the train and block up the link block on the disabled side to the same height as the one on the opposite side by means of suitable blocks placed in the link slot and fastened there securely, and proceed, handling full train.

76. Q.-What should be done in case of a broken reach rod or a broken reversing arm?

A.-Blocks should be placed in the link slots so that the link blocks would be in a position where the engine could start and handle the train; remove the broken parts and proceed.

77. Q.-What should be done in case a "blow-off" cock, a whistle or a safety valve should blow out or be broken off?

A. In case of a blow-off cock being blown out or broken the first thing to do is to put on both injectors and knock the fire out of the firebox or deaden it with fine, wet coal and close the dampers. Then notify the proper official and prepare to be towed in. If it is necessary that the crew bring the engine in it can be done. If there is a spare washout plug on the engine it may fit the hole; if so, it can be screwed in and the boiler filled with water and fired up. If this cannot be worked, fix up a hardwood plug that will just fit into the hole, then split the end of the plug that goes into the hole, make a wedge the same size of the hole and long enough to reach the inside sheet, then fit the end of the wedge into the end of the plug that has been split, place the wedge against the inside sheet of the firebox; then drive in the plug and the wedge will spread the end of the plug so that it will not be forced out. The boiler can now be filled up and the fire started and the engine run in with reduced steam pressure.

In case the safety valve or whistle is blown out or broken off, start both injectors, close the dampers, and if the water gets dangerously low knock out the fire or deaden it with fine, wet coal. When the pressure has all escaped take a tapering hardwood plug and split it into four pieces; tie a string to each piece and let them down separately into the hole where the whistle or safety valve blew out; then pull them up into the hole so that the large end of the plug will be inside of the boiler, then fill the boiler if necessary and build a new fire and proceed. The hole can also be plugged by driving a hardwood plug into the hole and placing a bar across the top of the plug, fastening both ends of the bar down to the hand rails.

78. Q.-What would you do to prevent further damage should a hole be knocked in the boiler in any manner?

A. The fire should be knocked out as quickly as possible; if this cannot be done, close the ashpan dampers and deaden the fire with fine, wet coal, then throw water on it to put it out. Notify the proper official and prepare to be towed in.

1. Heat and Energy.-Heat is the source of power. The energy contained in the heat is utilized in the steam locomotive by being imparted to water, thereby generating steam, the expansive force of which is then utilized to move the pistons in the cylinders, converting the energy contained in the combustibles by means of which the steam is generated, such as wood, coal or oil, into motion; therefore heat in any form is simply a form of motion.

This brings us then to the first requirement in building a locomotive, viz., the boiler. All boilers as used in locomotive practice are a modification of one general form, and consist of one or more cylindrical courses attached to a rectangular course. The round, or cylindrical, part of the boiler contains the flues, while in the rectangular course is placed the firebox. It is thus seen that locomotive boilers are of the horizontal multi-tubular type with internal fireboxes. There are five general types of locomotive boilers in use, viz., the wide-firebox (Fig. 1), the wagon-top (Fig. 2), the extended wagon-top (Fig. 3), the Belpaire (Fig. 4), and the straight-top (Fig 5).

The type of boiler used depends on the condition of the service, the kind of fuel and the character of the water, each form having its own advantages. Each form of locomotive boiler has also many modifications, as, for instance, the narrow-firebor type, in which the firebox fits between the frames, the boiler proper being either of the straight-top, wagon-top, extended wagon-top, or the Belpaire. The narrowfirebox type of boiler is used principally on the older type of eight-wheel engines (Fig. 2). As the size of engines increased the practice of dropping the firebox between the frames was discontinued, and the fireboxes were widened out and

set on top of the frames. This decreased the depth but increased the width. This width was afterward further increased by extending the firebox out beyond the frames and over the driving wheels, thereby producing what is known as a widefirebox. The wide-firebox has been still further modified in some instances by having the width increased to extreme proportions, into what is termed the "Wootten" firebox (Fig 6). The necessity for this latter type was due to the demand for increased grate area in order to burn culm or slack coal. Fig. 5 shows a general form of the ordinary straighttop boiler, other boilers being simply a modification of this type; therefore a general description of the construction of this type of boiler will apply to all others, with the exception of the modifications previously mentioned.

Referring to Fig. 5, the space A is termed the smokebox, which contains the steam pipes, the exhaust nozzle and draft appliances. The smokebox A is separated from the water space C by the front tube sheet B. Space C is termed the cylindrical course, and extends from the front to the back tube sheet. This space contains the tubes, commonly called flues, the same being fastened in the two tube sheets by being expanded in the holes of said tube sheets by means of expanding rollers, the firebox end of the tubes being further secured by hammering the tube over so as to form what is termed a bead. The rectangular part of the boiler, shown at D, contains the firebox E, in which combustion takes place. The firebox consists of a back tube sheet F, the crown sheet G, the door sheet H, and the two side sheets.

The cylindrical course of the boiler containing the tubes, on account of its form, requires no bracing to resist the internal

Fig. 3. The Extended Wagon-Top Locomotive Boiler