Of field studies of small combines

The term "small combine" refers to 5» and 6-ft powers take-off machines. These made their appearance on farms throughout the Corn Belt, (1) eastern, and southern states where combines had previously not been in common use.

With their introduction into these areas many ques­tions arose, particularly as to adaptability, cost of opera­tion and performance characteristics. Reliable data can be obtained only after the machines have been in use suf­ficiently long to determine their average life, acres harv­ested annually, cost of repairs, etc. It was felt, however, that data dealing with performance characteristics of small combines would be helpful in determining to what extent these machines may be used, particularly in re­placing binders in the Corn Belt and eastern states. With this objective, field work was begun.

Field--tests were made on approximately fifty 5- and 6-ft. and on forty 8- to 16-ft. combines, in harvesting wheat and oats. In making these tests, information was obtained as to field, crop, and weather conditions and as to cutter-bar and threshing losses. The procedure followed and type of equipment used in making field tests were the same as those used in the past,

Harvesting Wheat and Oats. At the time of the tests wheat and oats in the Corn Belt were generally difficult to harvest. The straw was heavy and lodged, weed growth abundant, and the grain Might, both as to weight per bush­el and yield. Under such conditions threshing losses-threshed and unthreshed grain thrown' out with the straw and chaff — were high, with no significant differences with respect' to size of machine.. The small machines could, in general, handle (2) a bulky crop infested with green weeds (3) better than could the large ones, because of greater thrashing and separating capacity per foot width of" cut.

The small-grain (4) harvest season in the Corn Belt was ideal for the use of combines. The weather was dry and hot, few weeds in evidence, practically no lodged grain, and the yield good in some localities. For these reasons, threshing losses were very low.

In harvesting wheat in Illinois, threshing losses for the small combines tested averaged less than 1.0 per cent, cut­ter-bar losses approximately 1.0 per cent, with a total loss of about, 1.7 per cent. With 8-ft. and larger combines, threshing losses approximated 1.3 per cent and cutter-bar losses 1.7 per cent, with a total loss of about 3.0 per cent. In oats, losses were considerably higher with all sizes of machines than in wheat. With 5- and 6-ft. com­bines, threshing losses approximated 2.7 per cent and cut­ter-bar losses L9 per cent with a total of about 4.6 per cent. Averages for the large machines approximated 5.0, 1.6, and 6.6 per cent respectively, for threshing, cutter-bar, and total losses.

In Indiana in harvesting oats threshing and cutter-bar losses were larger for the 5- and 6-ft. machines than for those of larger size. Threshing losses approximated 3.0 per cent, and cutter-bar losses about 1.0 per cent for the 5- and 6-ft. combines, compared with 2.0 per cent thresh­ing and less than 1.0 per cent cutter-bar losses for the larger ones.

Results of tests made in Ohio in wheat show that thresh­ing losses for the small combines approximated 0.6 per cent, and for the large machines about 1.0 per cent. Cut­ter-bar losses for the small ones averaged about 2.4, in comparison with 2.1 per cent for the large machines. To­tal losses were about the same for the two size groups, 2.9 per cent for the small and 3.1 per cent for 8-ft. and larger,

Data obtained on ground speeds in harvesting small grain show that the small machines are generally pulled at a higher speed, indicating greater duty per foot of cut­ter-bar than with other sizes. In harvesting wheat in Illi­nois, the average speed of the small machines tested was 3.6 mph. and the large ones 2.6 mph. In oats, in the same state, the average speeds were 4.0 and 3.2 mph., respec­tively, for the two size groups. The data from Indiana show that the small machines average 3.5 and the large ones 2.7 mph. In Ohio, there was only 0.7 mph. difference in speeds; the small ones averaged 3.8 and the large ones 3.1 mph. in wheat. Under-the crop and field conditions at the time the small machines travelling at from 4 to 5 mph. were saving as much grain as those travelling at 3 mph. or less. Thus under favourable crop and field conditions the 5- and 6-ft. machines will usually give satisfactory re­sults when pulled at 5 mph. which is approximately twice as fast as the average speed of other sizes. However un­der unfavourable crop conditions, high machine losses are usually associated with high ground speed.

Small power take-off combines mounted on rubber tires are usually pulled at a speed of from 0.5 to 1.0 mph. fast­er than machines equipped with an auxiliary engine and steel tires.

Another point of interest in connection with machine losses for all sizes in wheat and oats is that threshed grain thrown out with the straw and-chaff is usually much great­er than that left in unthreshed heads, frequently from two to ten times as much. From this it appears that the thresh­ing unit on combines is more effective than the separat­ing and cleaning units.

NOTES.

(1)the Corn Belt — район выращивания кукурузы в США, «куку­рузный пояс»

(2)to handle — справляться с (зд.)

(3)infested with green weeds — заполненный зелеными сорняками

(4)small grain — мелкозерновые культуры