6 BULLETIN 480, U. S. DEPARTMENT OF AGRICULTURE. 



MOTOR-TRUCK SPRAYER. 1 



The first motor-truck sprayer used in New England was built in 

 the winter of 1910 along lines suggested by the writer. This sprayer 

 was used by the State of Massachusetts and gave such satisfactory 

 results that several others have been built and are being used in that 

 State. (PL I.) 



In the fall of 1915 a machine of this type was built for the Bureau 

 of Entomology and has been used to great advantage during the past 

 summer. 



Profiting by the experience secured when the other machines were 

 constructed, the one built for the Bureau was improved and per- 

 fected in many respects, so as to render its operation more perfect 

 and economical. A machine of this type is particularly useful where 

 work has to be done in locations demanding the use of long lines of 

 hose and where water must be hauled long distances. It can ac- 

 complish more work in a single season than four horse-drawn high- 

 power sprayers and can be operated more economically on account 

 of saving time on the road and reduction in the number of men 

 needed. 



One and one-eighth inch hose is used on this machine, as it does 

 not offer as much resistance as the hose of smaller diameter, and 

 makes it possible to maintain proper pressures at the nozzle when 

 2,500 feet of hose is required. Two automatic safety release valves 

 are connected to the pump, one set at 300 pounds and one at 500 

 pounds. The maximum pressure needed on 2,500 feet of lj-inch 

 hose to obtain 225 pounds at the nozzle is 475 pounds, against ap- 

 proximately 600 pounds in the case of 1-inch hose. 



TThen 1-inch hose is used the pressure must be increased 50 pounds 

 for every 100 feet that the nozzle is operated above the level of the 

 sprayer. With 1^-inch hose a slightly greater pressure is required. 

 This matter must be given careful attention when lines of hose are 

 run to hilltop areas which are at much greater elevations than the 

 sprayer. 



TThen the sprayer truck combination is not in use the pump and 

 tank attachment can be easily removed and a commercial body 

 attached which can be used in transporting supplies to and from the 

 field. (PI. VII.) 



The construction of the motor-truck sprayer is of special design, 

 owing to the double work which it is called upon to perform. As 

 the truck must propel itself and at the same time maintain high 



1 Since this manuscript was prepared a more powerful truck sprayer has been designed. 

 For this purpose a 5-ton truck with a worm drive and a pump of greater capacity has 

 been used. This outfit is to be used in difficult spraying work in the border territory of 

 the gipsy moth infested region. 



