Water Terminals

Air-Conditioning.

Air-conditioning has been one of the most outstanding railway developments during recent years and has increased materially railroad passenger travel. Air-condition ing directly affects the passengers and adds much to their comfort, both in summer and winter.

It is the function of an air-conditioning system to control scien tifically the temperature and humidity of a car in winter as well as in summer, and the heating control is a very important part of an air-conditioning system, thereby differing from a strictly cooling system for use in hot weather only. Ideal air-conditioning for railway cars is the simultaneous control of the factors affect ing both the physical and chemical conditions of the atmosphere within the railway car. These factors include temperature, hu midity, air motion, air distribution, ionization and elimination of dust, bacteria, odours and toxicity. A dependable power supply is necessary to provide for the equipment involved in the proper air-conditioning of a railway car. This equipment controls the ventilation, filtering, heating, cooling and humidity.

The principal methods of air-conditioning railway passenger cars are mechanical (both electro and direct), steam ejector and ice activated. The refrigerant most commonly used in the me chanical type of cooling system is "dichlorodifluoromethane." There are several types of drive mechanisms through which power is transmitted from the car axle to the cooling equipment. These comprise the gear type of drive using either hypoid, spur or bevel gears ; the belt and gear type of drive using a V-belt and bevelled gear ; the belt type of drive using a "V" or flat belt without a gear, and the friction type of drive. Generators where used with an electro-mechanical system will range upwards from 5-kw. There is also one system using an internal combustion engine driving a directly connected compressor.

The insulation of railway cars is very important when consider ing air-conditioning. To maintain a difference of 20° between the outside and inside temperature of a car with 3" of insulation and double windows will require about 1.3 tons of refrigeration, whereas a car with only I" of insulation and single windows will require 3.1 tons of refrigeration. An air-conditioned car will use from ioo,000 to 125,0m cu. ft. of air per hour. This will approxi mate 25% fresh air and 75% re-circulated air. It is important that proper ducts be provided to permit the intake of fresh air and control the escape of air to the outside atmosphere. The Associa tion of American Railroads has determined by tests that the mini mum air change required in an air-conditioned railway car is 10 cu. ft. of air per minute, per passenger. Therefore, an air

conditioning installation on a 6o-passenger car should be so de signed as to deliver not less than 600 cubic feet of air per minute. The total cost of air-conditioning consists of four items; namely, (1) cost of installation ; (2) cost of terminal facilities ; (3) cost of maintenance and (4) cost of operation.

The economics of air-conditioning from an operating standpoint is affected by a number of factors ; namely, the length of the cool ing period and the atmospheric conditions prevailing during that period, the average speed in miles per hour and the total car miles per year. These factors must be considered in order to select a system from the standpoint of economy.

Rolling Stock Prices.

During the year 1927 the average pur chase prices for freight cars were $i,800.00 to $2,200.00. During 1926 the average price of all steel freight cars averaged 4•73? a pound, and composite wood and steel freight cars averaged a pound. Seventy ton all steel hopper cars cost from $2,200.00 to $2,500.00, while a so ton box car cost $2,200.00. The price of an ordinary coach with 6-wheel trucks ranged from $27,000.00 to $33,000.00. Dining cars ranged from $43,000.00 to $51,000.00, depending upon the interior furnishings. Baggage cars ranged from $18,000.00 to $20,000.00.

Weight of Passenger Train Equipment.

Main line passen ger equipment cars in America weigh from i oo,000 to 15o,000 pounds. The average Pullman car varies between 15o,000 and 16o,000 pounds. Suburban cars weigh between 8o,000 and 120,000 pounds. Dining cars on American railroads weigh between 16o,000 and 175,000 pounds. The American railroads have to haul twice as many pounds of equipment per Pullman passenger as per day coach passenger. In the United States this condition has been brought about by demands of the travelling public for a more lux urious and convenient mode of transportation. The limits seem to have been reached as far as dead weight and size are concerned and the trend is now to reduce weight. What seems to be excessive weight is also the outcome of the desire on the part of railroad offi cials to provide as safe a means of transportation as possible. Any reduction in weight should not be made at the sacrifice of strength and safety. Some experiments have been made with the use of aluminium in car construction. Designers have tried to produce double deck cars in order to decrease the dead weight per passen ger. Alloy steel is also coming into general use in car construction.