The Vessel Toiler's Machinery.

In previous issues we have given various

particulars about the vessel Toiler,

which was built in England, and which

is now in Canada engaged in the lake

trade. The following additional information

will be of interest:—

The propelling machinery consists of

two Diesel oil engines driving twin

screws which develop 180 b.h.p. each at

about 250 revolutions per minute. Their

[p. 1179]

arrangement is indicated by sectional

drawing, fig. 1, and the photograph, fig.

2. The weight of the engines is only

about half that of steam engines and

boilers of the same power, while the

fuel consumption is only one-fourth the

weight of that necessary if coal were

being used in the ordinary way, so that

there is a very considerable addition to

the dead-weight capacity available for

cargo, amounting in this case to about

140 tons, compared to the steam-driven

ship of similar dimensions. The Toiler

is of Canadian canal dimensions, being

248 ft. long. 42 1/2 ft. beam. and 19 ft.

molded depth. The cubical capacity

available for cargo is also considerably

increased both owing to the smaller

space occupied by the engines and the

fact that fuel can be carried in the

double bottom when burning oil. One

of the most noteworthy features of the

design is the manner in which reversing

is accomplished by means of compressed air. Fig. 3 shows the arrangement

of the engine in diagrammatic form.

The four two-cycle combustion cylinders

marked 1 represent the working motor,

the two double-acting cylinders marked

2 constituting what are termed the

manoeuvering motor. Under normal

circumstances the manoeuvering motor

draws air from the atmosphere from the

pipe 5 and delivers it slightly compressed

through the channel 6 into the

working cylinders 1. In the working

cylinders this air is compressed to 36-38

atmospheres in order to assist the combustion

and the development of power.

The products of combustion are driven

into the cylinder 17 and pass thence

into the open air. When manoeuvering

the manoeuvering motor is connected

with a compressed air reservoir 9 instead

of the atmosphere by turning the

lever 18. The air used during manoeuvering

is automatically replenished by the

air pump 8, which begins to act as soon

as the pressure in the reservoir sinks below

a certain amount. The liquid fuel

is drawn from the tank 14 through the

filter 15 by the fuel pump 16, and delivered

to the fuel valves 13, being driven

thence into the combustion chambers by means of the compressed air

supplied from the air pump 11; 3 is the

fly wheel and 4 the thrust block.

The construction and working of the

manoeuvering cylinders will be better

understood from figs. 4 and 5. The

circle of fig. 5 shows the order of events

during one revolution of the engine,

considering this cylinder to act firstly as

an air pump under direct running, and

secondly, as a compressed air engine

when manoeuvering. Shortly after the

piston has passed the upper dead centre

the slide valve opens at 1 and air

is drawn, into the cylinder until the

valve closes at 2 (corresponding to the

line A B on the imaginary indicator diagram).

From 2 to 3 (B to C) there is

a slight decrease in pressure which is

neutralized at 3 when the piston, passes

an opening in the cylinder wall (35 in

fig. 4) thus placing the cylinder in communication

with the outside air. After

the piston passes the lower dead centre

this opening is closed again at 4 and

compression ensues up to 5 (D to F),

after which the compressed air is forced into the channel leading to the

working cylinder. When manoeuvering,

atmospheric air is cut off and compressed

air admitted from 1 to 2, the indicator

diagram becoming 11 1 J D E D

F G.

The action of the internal combustion

cylinders is illustrated in fig. 6. Air

is supplied, under pressure to the receiver

26 and passes thence through the

passage 41, which is laid open to the

cylinder when the piston is at the bottom

of the stroke. As the piston rises

this passage is closed and the air is

compressed until at about the top of the

stroke a small supply of oil is admitted

through the valve 25 and the resulting

explosion provides the necessary source

of power, the waste gases escaping

through the opening 42 as the piston

descends. The fuel valve 25 is controlled

in the ordinary way by means of

cams.

An ingenious method has been adopted

for regulating the oil pumps and

valves. Briefly the arrangement is such

that during the period in which the motor

revolves forward after the levers

have been partly reversed the pumps

supply no oil to the valves, thus avoiding

contrary explosions. The manoeuvering

arrangements have proved very

satisfactory in the Toiler and it is claimed

that the engine can be changed from

full speed ahead to full speed astern

more quickly even than a steam engine.

On one occasion she was submitted to

an unusually severe test on returning to

her builders' yard, when she was completely

turned around and placed alongside

a quay. In 16 minutes no less than

31 manoeuvers were accomplished and

the pressure never sank below eight atmospheres,

the normal being 10 atmospheres.

The question of auxiliary machinery

for the Toiler, in view of the absence of

steam, required special consideration.

The auxiliaries consist of a ballast donkey

pump and a sanitary donkey pump

in the engine room, and a capstan aft

and a windlass forward on the deck,

besides the steering gear. All these are

driven by compressed air, which is supplied

by a separate compressor driven

[p. 1181]

by a 30 h.p. Diesel engine. In addition

there is a small electric light engine

working on paraffin. The cabin heating

is accomplished by a hot water system.