18 
BULLETIN 1373, U. S. DEPARTMENT OF AGRICULTURE 
is to provide a hood on the belt loader and connect this hood by 
means of a flexible hose to the main suction trunk line. Extra time 
and labor are required to make the connection, and it is generally 
considered unsatisfactory. A number of manufacturers of mill ancl 
elevator equipment are trying to develop a satisfactory method of 
applying suction to movable equipment. At present the only sug- 
gestions that can be made for the control of dust at movable belt 
loaders are to inclose the loader tight enough to keep the dust from 
escaping and to provide suction at the discharge spout through 
flexible couplings. 
The choke-feed belt loader is the most satisfactory of all types of 
belt loaders, because it creates less dust than any other known type. 
From an operative standpoint it has many advantages, especially in 
mixing. Very little dust rises from the grain as it is discharged upon 
the belt, but the little cloud that is formed is cared for by a hood (fig. 
14). 
Suction hood on choke-feed belt loader 
AT TKIPPERS 
In a few elevators it is possible to discharge grain direct from the 
scale hopper or elevator head to the storage bins, but in the larger 
houses this is generally impossible and conveyor belts with trippers 
are used. This agitation of the grain while it is being tripped from 
the belts to the bins stirs up great clouds of dust. It has been dim- 
cult to design suitable apparatus to collect the dust at this point. 
Because the tripper is moved at frequent intervals, a satisfactory 
connection between the dust-collecting hoods on the tripper and the 
main suction trunk line is difficult. One method suggested for the 
solution of this problem provides for the use of specially constructed 
7-inch rubber hose to connect the suction line and the movable equip- 
ment. 
Experiments are now being made with a jointed metal spout, 
which connects the tripper with a suction trunk line installed directly 
over the path of travel of the tripper. An automatic means of 
making the connection between the tripper and the suction line 
would help to solve the problem. Such an installation must be 
simple, substantial, and automatic or easily operated. 
