附 录A
Refrigerator Car
Background
After the end of the American Civil War, Chicago, Illinois emerged as a major railway center for the distribution of livestock raised on the Great Plains to Eastern markets. Getting the animals to market required herds to be driven up to 1,200 miles (1,900 km) to railheads in Kansas City, Missouri, where they were loaded into specialized stock cars and transported live (\also caused tremendous weight loss, with some animals dying in transit.
Upon arrival at the local processing facility, livestock were either slaughtered by wholesalers and delivered fresh to nearby butcher shops for retail sale, smoked, or packed for shipment in barrels of salt. Costly inefficiencies were inherent in transporting live animals by rail, particularly the fact that about sixty percent of the animal's mass is inedible. The death of animals weakened by the long drive further increased the per-unit shipping cost. Meat packer Gustavus Swift sought a way to ship dressed meats from his
Chicago packing plant to eastern markets.
Early attempts at refrigerated transport
Attempts were made during the mid-1800s to ship agricultural products by rail. As early as 1842, the Western Railroad of Massachusetts was reported in the June 15 edition of the Boston Traveler to be experimenting with innovative freight car designs capable of carrying all types of perishable goods without spoilage. The first refrigerated boxcar entered service in June 1851, on the Northern Railroad (New York) (or NRNY, which later became part of the Rutland Railroad). This \since it was only functional in cold weather. That same year, the Ogdensburg and Lake Champlain Railroad (O&LC) began shipping butter to Boston in purpose-built freight cars, utilizing ice for cooling.
The first consignment of dressed beef left the Chicago stock yards in 1857 in ordinary boxcars retrofitted with bins filled with ice. Placing meat directly against ice resulted in discoloration and affected the taste, and proved impractical. During the same period Swift experimented by moving cut meat using a string of ten boxcars with their doors removed, and made a few test shipments to New York during the winter months over the Grand Trunk Railway (GTR). The method proved too limited to be practical.
Detroit's William Davis patented a refrigerator car that employed metal racks to suspend the carcasses above a frozen mixture of ice and salt. He sold the design in 1868 to George H. Hammond, a Detroit meat packer, who built a set of cars to transport his products to Boston using ice from the Great Lakes for cooling. The load had the tendency of swinging to one side when the car entered a curve at high speed, and use of the units was discontinued after several derailments. In 1878 Swift hired engineer Andrew Chase to design a ventilated car that was well insulated, and positioned the ice in a compartment at the top of the car, allowing the chilled air to flow naturally downward. The meat was packed tightly at the bottom of the car to keep the center of gravity low and to prevent the cargo from shifting. Chase's design proved to be a practical solution to providing temperature-controlled carriage of dressed meats, and allowed Swift and Company to ship their products across the United States and internationally.
Swift's attempts to sell Chase's design to major railroads were rebuffed, as the companies feared that they would jeopardize their considerable investments in stock cars, animal pens, and feedlots if refrigerated meat transport gained wide acceptance. In response, Swift financed the initial production run on his own, then — when the American roads refused his business — he contracted with the GTR (a railroad that derived little income from transporting live cattle) to haul the cars into Michigan and then eastward
through Canada. In 1880 the Peninsular Car Company (subsequently purchased by ACF) delivered the first of these units to Swift, and the Swift Refrigerator Line (SRL) was created. Within a year the Line’s roster had risen to nearly 200 units, and Swift was transporting an average of 3,000 carcasses a week to Boston, Massachusetts. Competing firms such as Armour and Company quickly followed suit. By 1920 the SRL owned and operated 7,000 of the ice-cooled rail cars. The General American Transportation Corporation would assume ownership of the line in 1930.
The \
The use of ice to refrigerate and thus preserve food dates back to prehistoric times. Through the ages, the seasonal harvesting of snow and ice was a regular practice of many cultures. China, Greece, and Rome stored ice and snow in caves or dugouts lined with straw or other insulating materials. Rationing of the ice allowed the preservation of foods during hot periods, a practice that was successfully employed for centuries. For most of the 1800s, natural ice (harvested from ponds and lakes) was used to supply refrigerator cars. At high altitudes or northern latitudes, one foot tanks were often filled with water and allowed to freeze. Ice was typically cut into blocks during the winter and stored in insulated warehouses for later use, with sawdust and hay packed around the ice blocks to provide additional insulation. A late-19th century wood-bodied reefer required re-icing every 250 miles (400 km) to 400 miles (640 km).
By the turn of the 20th century manufactured ice became more common. The Pacific Fruit Express (PFE), for example, maintained 7 natural harvesting facilities, and operated 18 artificial ice plants. Their largest plant (located in Roseville, California) produced 1,200 short tons (1,100 t) of ice daily, and Roseville’s docks could accommodate up to 254 cars. At the industry’s peak, 1,300,000 short tons (1,180,000 t) of ice was produced for refrigerator car use annually.
Top Icing
Top icing is the practice of placing a 2-inch (51 mm) to 4-inch (100 mm) layer of crushed ice on top of agricultural products that have high respiration rates, need high relative humidity, and benefit from having the cooling agent sit directly atop the load (or within individual boxes). Cars with pre-cooled fresh produce were top iced just before shipment. Top icing added considerable dead weight to the load. Top-icing a 40-foot (12 m) reefer required in over 10,000 pounds (4,500 kg) of ice. It had been postulated that as the ice melts, the resulting chilled water would trickle down through the load to continue the cooling process. It was found, however, that top-icing
only benefited the uppermost layers of the cargo, and that the water from the melting ice often passed through spaces between the cartons and pallets with little or no cooling effect. It was ultimately determined that top-icing is useful only in preventing an increase in temperature, and was eventually discontinued.
Refrigerator cars required effective insulation to protect their contents from temperature extremes. \derived from compressed cattle hair, sandwiched into the floor and walls of the car, was inexpensive but flawed — over its three- to four-year service life it would decay, rotting out the car's wooden partitions and tainting the cargo with a foul odor. The higher cost of other materials such as \their widespread adoption. Synthetic materials such as fiberglass and polystyrene foam, both introduced after World War II, offered the most cost-effective and practical solution.
Mechanical refrigeration
In the latter half of the 20th century mechanical refrigeration began to replace ice-based systems. In time, mechanical refrigeration units replaced the \of personnel required to re-ice the cars. The \door was introduced experimentally by P.F.E. (Pacific Fruit Express) in April 1947, when one of their R-40-10 series cars, was equipped with one. P.F.E.'s R-40-26 series reefers, designed in 1949 and built in 1951, were the first production series cars to be so equipped. In addition, the Santa Fe Railroad first used plug doors on their SFRD RR-47 series cars, which were also built in 1951. This type of door, provided a larger six foot opening, to facilitate car loading and unloading. These tight-fitting doors were better insulated and could maintain a more even temperature inside the car. By the mid-1970s the few remaining ice bunker cars were relegated to \service, where crushed ice was applied atop the commodity.
Cryogenic refrigeration
The Topeka, Kansas shops of the Santa Fe Railway built five experimental refrigerator cars employing liquid nitrogen as the cooling agent in 1965. A mist induced by liquified nitrogen was released throughout the car if the temperature rose above a pre-determined level. Each car carried 3,000 pounds (1,400 kg) of refrigerant and could maintain a temperature of minus 20 degrees Fahrenheit (?30 °C). During the 1990s, a few railcar manufacturers experimented with the use of liquid carbon dioxide (CO2) as a cooling agent. The move was in response to rising fuel costs, and was an attempt to eliminate the standard mechanical refrigeration systems that required periodic maintenance. The CO2 system can keep the cargo frozen solid as long as 14 to
