UNITED STATES DEPARTMENT OF AGRICULTURE 
May, 1926 
Washington, D. C. 
COMPARATIVE EFFICIENCY OF WIRE-BASKET BUNKERS IN REFRIG- 
ERATOR CARS 
By R. G. Hitu, Associate Horticulturist, W. S. GRAHAM, Junior Physiologist, 
R. C. WricHt, Associate Physiologist, and GrEorGE F. TAytor, Associate 
Biophysicist, Office of Horticulture, Bureau of Plant Industry 
CONTENTS 
Page Page 
The car-cooling problem__-____-__ = 1 | Temperatures maintained____._____ 4 
Installation of wire-basket bunkers_ 2 | Comparative study of temperatures_ 9 
Renmin Of O8t Trips Zab SUMIMArY: = 2 ee a ee ee 10 
THE CAR-COOLING PROBLEM 
Refrigerator cars in the fruit and vegetable service to-day are 
provided with compartments for ice at each end of the car. These 
compartments are filled through hatches fitted with insulated plugs 
located at each corner of the roof, and partitions, or bulkheads, 
separating them from the loading space. 
Although the designers of this type of car differ in opinion as 
to the kind of ice bunker to be installed, all recognize the fact that 
the cooling of a refrigerator car is entirely dependent upon gravity 
for the circulation of air within it. ‘This circulation is brought 
about by the cooling of the air as it comes in contact with the ice. 
The cooled air slowly drops to the floor of the bunker and issues 
therefrom into the loading space, where it is brought in contact with 
the load and again slowly rises as it becomes warmer and passes 
through and over the load back into the bunker. 
Under these conditions the movement: of air is exceedingly slow, 
and in order to accelerate it and to obviate the pos sibility ‘of any 
obstruction that would block it great care must be exercised in the 
construction of the car. To obtain the maximum degree of cooling 
much attention has been paid to the construction of the ice compart- 
ment, or bunker, and in connection with this study consideration has 
been given also to the insulation of the car, without which the effec- 
_ tiveness of the ice in the bunker would be lost. 
Not until the year 1918 was any attempt made to standardize the 
refrigerator car. In that year, as a result of the efforts of the 
73724—26-——1 1 
