164 CARGO TRANSFERENCE AT STEAMSHIP TERMINALS. 
cranes, and other types, but without the usual swinging jib. The motive 
power is electricity. 
In accordance with the above, and from a careful consideration of all 
types of hoisting and conveying machinery, the traveling crane is the only 
machine which will serve large spaces without rehandling. 
The standard overhead traveling-shop crane takes up no floor space in 
its operation. No aisles or alley ways need to be reserved from the valuable 
floor space so as readily to reach any consignment pile. It can tier most 
advantageously, and its great positive value is proved by its universal 
adoption. 
Although it will tier and serve space without rehandling and produce 
no floor congestion, yet it will not give the rapidity for the continuous service 
required in freight movements. 
If, after a load has been raised, many men must wait for the crane to 
pass to the end of the station, place its load and return, there would be much 
labor delay. 
If, by attaching a track upon each side of a crane as is now done in 
Germany, Holland, Belgium and France, and adding a gliding or sliding 
connection by switches between the movable and fixed tracks, so that trans- 
fer-tractors with their traveling trains can pass from the fixed tracks to the 
movable cross tracks, utilizing the overhead shop crane for the interior of the 
shed and the traveling gantry crane with a loop or the walking crane for 
either interior or exterior work, then there can be added to the other indis- 
pensable features of crane movements the essential continuous rapidity. 
Conveying and Hoisting Machinery.—The conveying mechanism consists 
of a transfer-tractor drawing after itself four or more trailers with an electric 
hoist suspended beneath each trailer. The four hoists are controlled by the 
transfer-man who rides in the tractor. ‘The hoists can be operated simul- 
taneously or independently of each other. Each hoist raises or lowers one 
consignment. The speed of travel is between eight and ten miles per hour. 
Each hoist has a capacity of two tons with a temporary reserve capacity, 
at the usual hoisting speed, of from 75 to 200 feet per minute. ‘Iwo hoists 
can be combined and raise four tons. 
As each consignment will average about 1,500 pounds, therefore there 
will be an average train load of 6,000 pounds. ‘This method means that the 
freight will be assorted as it is raised not requiring skilled labor, and then 
distributed and tiered. There are, therefore, the following mechanical 
elements: 
An overhead runway system with electric carriers and hoists designated 
either as transporters, transfer-tractors and transfer-hoists or by many other 
