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LESSON FOURTEEN

TYPICAL WATER COOLING SYSTEMS

Q. What is the common method of cooling by water?

A. In usual water cooling systems the cylinder is provided with a water jacket which is kept constantly filled with water, this passing out of the jacket when it becomes heated and returning again when it has been cooled by external means.

Q. Name the two systems of water cooling.

A. There are two common methods of cooling by water, the simplest of these being the thermo-syphon or natural system; the other is the pump circulation method.

Q. How does the thermo-syphon system operate?

A. The conventional arrangement of parts of a thermo-syphon cooling system is outlined at Fig. 131. A radiator or water container supplies water to the lower portion of the water jacket by means of a manifold pipe and after the water becomes heated it passes out of the top of the water jacket, through another manifold to the top of the radiator. The circulation is maintained by a natural law that hot water being lighter than cool water will rise and be replaced by water at lower temperature. In the system outlined the heated water from the engine passes through the radiator and is cooled and falls to the bottom of the radiator where it is again conducted to the bottom of the cylinder. Circulation is maintained automatically as long as the engine is in operation and the radiator is filled with water.

Another method of cooling by the thermo-syphon system, in which the radiator is carried at the back of the power plant instead of at the front end, is shown at Fig. 132. The principal parts consist of a radiator, which serves as a water cooler and storage tank,

a centrifugal fan member to draw air through the radiator, and suitble pipes to connect the water jacket with the upper and lower portions of the radiator respectively.

Q. What precautions are necessary to successfully use thermo-syphon cooling?

A. Where the water is circulated by natural means it is necessary to have a radiator of large capacity and also large water jackets and manifold pipes as circulation due to the heating and cooling of water is more sluggish than in systems where a pump is employed.

RADIATOR.

Fig. 131.-Illustrating Action of Simple Thermo-Syphon Water-Cooling System.

Thus large water passages are necessary so the flow of liquid will not be impeded by small water spaces or resistance of small bore water pipes.

Q. What are the advantages of the forced circulation method? A. When a pump is employed to circulate liquid, as shown at Fig. 133, the cooling system may be made lighter because less water is needed in the radiator and the water pipes and water spaces around the cylinders may be made smaller. The pump is driven by mechanical connection with the engine crankshaft and as the speed

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Fig. 132.-Thermo-Syphon

Cooling System Employing Radiator Placed at Dash Back of Motor.

of the motor increases, the circulation of the water becomes more energetic. A more efficient form of radiator having smaller passages, which will cool the water quicker than large passages designed for free flow, may be used.

Q. Name principal parts of forced circulation system.

A. The principal parts of a forced circulation system used on Packard cars are clearly outlined at Fig. 134. The water is taken

from the lower portion of the radiator by the pump from which it is delivered to a manifold or water inlet header attached to the lower portion of the water jackets immediately under the inlet valve. The heated water is forced out of the top of the water jacket, through short cast fittings joined together by lengths of rubber hose. The water passes to the top of the radiator and as it flows through the narrow passages it becomes cooled because the tubing of which the radiator is composed is kept at a low temperature

Radiator

Pump

Fig. 133.-Conventional Forced Circulation System Employing Mechanically Driven Pump to Insure Movement of Water.

by a current of air drawn through the radiator by a V belt driven, cast aluminum fan.

Q. How many types of pumps are commonly used in water cooling systems?

A. The forms of pumps utilized to circulate the water through the radiator and water-jacket spaces are usually of the rotary type,

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Fig. 134.-Water Cooling System Employed on Packard Motor Cars Showing Arrangement of Components, Including Circulating Pump, Radiator and Cooling Fan.

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