Gasoline engines are used to some extent to operate concrete mixers. Their use so far has been limited chiefly to portable plants such as are used for street work. The fuel for the gasoline engine is much easier moved from place to place than the fuel for a steam engine. Another advantage that the gasoline engine has over the steam engine is that it does not require the constant attention of an engineer.

There are two types of engines - the horizontal and the vertical. The vertical engines occupy much less floor space for a given horsepower than the horizontal. While each type has its advantages and disadvantages, there does not really appear to be any very great advantage fo one type over the other. Both types of engines are

Fig. 132. Ransome Disc Crank Vertical Engine.

Fig. 132. Ransome Disc Crank Vertical Engine.

Table XIX. Dimensions For Ransome Engines

No. of Mixer

1

2

3

4

Size of Batch

10 cu. ft.

20 cu. ft.

30 cu. ft.

40 cu. ft.

Capacity per hi

(Cu. yds.)

10

20

30

40

Horse-Power Required

Engine

6 by 6

7 by 7

8 by 8

9 by 9

Rated

7 h. p.

10 h. p.

14 h p.

20 h. p.

Boiler

30 by 72

36 by 7S

36 by 96

42 by 102

Rated

10 h. p.

15 h. p.

20 h. p.

30 h. p.

Speed of Drum

(Rev. per Min.)

16

15

14 1/2

14

Speed of Driving Shaft (Rev. per Min.)

116

122

94

99

what is commonly known as four-cycle engines. In the operation of a 4-cycle engine, four strokes of the piston are required to draw in a charge of fuel,compress and ignite it, and discharge the exhaust gases. Fig. 133 shows a vertical gasoline engine made by the International Harvester Company. The quantity of gasoline consumed in ten hours, on an average, is about one gallon for each rated horse-power for any given size of engine. At 15 cents per gallon for gasoline, the hourly expense per horse-power will be 1.5 cents. 337. Hoisting Concrete. When the concrete requires hoisting, it is done sometimes by the same engine that is used in mixing the concrete. It is generally considered better practice on large buildings to have a separate unit to do the hoisting. If it is possible to use a standard hoist, it is usually economical to do so. These hoists are equipped with automatic dump buckets.

Fig. 133. Vertical Gasoline Engine.

Fig. 133. Vertical Gasoline Engine.

Fig. 134 shows a standard double-cylinder, double-friction-drum hoisting engine of the Lambert type. This type of engine is designed to fulfil the requirements of a general contractor for all classes of derrick work and hoisting. Steam can be applied by a single boiler, or from a boiler that supplies various engines with steam. The double friction drums are independent of each other; therefore one or two derricks can be handled at the same time, if desired. This hoist is fitted with ratchets and pawls, and winch-heads attached to the end of each drum-shaft. The winch-heads can be used for any hoisting or hauling desired, independent of the drums. These engines are also geared with reversible link motion.

Fig. 134. Lambert Hoisting Engine.

Fig. 134. "Lambert" Hoisting Engine.