Combine Harvesters

Bushels per acre, not acres per day, must be the aim of the combine operator who wants the maximum amount of grain from a given crop.

To maintain an even flow of material through the ma-chine is possible by varying land speed according to crop volume. No specific recommendations can be given in this respect - the driver must make his variations almost instinctively to maintain the even rhythm characteristic of wellfed threshing mechanism.

Cylinder speed controls threshing; therefore it should be matched with both the volume and condition of the crop. Heavy and damp crops require higher speeds than do light and dry crops. A cylinder speed which is too low for damp material will leave unthreshed grain in the head. On the other hand, to thresh dry grain at too high a speed causes excessive chaff.

The concave is as important for separation as for threshing. It is an adjustable stationary grid against which the drum rubs out the grain. In reasonable harvesting conditions, it should be about 5/16 in. from the front of the cylinder.

If cracked grain appears, lower the front of the concave and reduce the cylinder speed; if grain tends to remain in the head, raise the front end and increase the cylinder speed.

Straw-walkers should be used to separate only the minimum of grain. Loss over the walkers indicates that the straw has been overloaded with grain, which would have been removed at the cylinder and concave had they been correctly adjusted.

As a general rule, sieves lose more gram through lack of wind than from excess. Grain goes out with the chaff when the latter is allowed to sit on the sieves. This can be prevented by adjusting the fan air-inlet shutter so that the outlet blast is strong enough to keep the chaff riding above the grain. (1)

Before starting a combine, even for a preliminary run, lubricate it according to the manufacturer's instructions. This routine must be observed throughout the season, for it usually takes longer (2) to cure a fault caused by lack of lubrication that it takes to lubricate the complete machine.

II

THE MASSEY-HARRIS Nr. 750 (3) COMBINE HARVESTER

The Massey-Harris Nr. 750 Combine is a trailed machine incorporating a 5-ft. 6-in. cutter bar and a 5-ft. wide rasp-bar type of threshing cylinder. (4) The straw passes straight through, and the grain is bagged (5) from a rotating cylindrical screen.

The cylinder is vee-belt driven from the largest of the three pulleys incorporated in the drive-shaft assembly. The effective diameter of this pulley and that on the cylinder shaft are quickly adjustable so that the cylinder speed can be varied to anything between 500 and 1,750 r.p.m. without affecting the speed of the other components.

The Massey-Harris Nr. 750 cylinder speeds and concave settings for various crops are as follows:

1. If grain is not being threshed out of heads, increase cylinder speed.

2. If grain is being cracked or if straw is being ground up excessively, reduce cylinder speed (Return gleanings to straw rack), etc.

NOTES:

(1) to keep the chaff riding above the grain - и постоянно гнала мя

кину над зерном

(2) it takes longer — требуется больше времени

(3) Massey-Harris Nr. 760 — марка комбайна

(4) a raspbar type of threshing cylinder — бильный барабан, барабан бильного типа

(5) is bagged — ссыпается в мешки

1. Study the following words:

Preliminary, crop, unthreshed, crop, chaff, grid, outlet, separation, pulley, wellfed, excessive, blast, instinctively

2. Complete the sentences with appropriate words from the text:

a) … an even flow of material through the ma-chine is possible by varying land speed according to crop volume.

b) …. is as important for separation as for threshing.

c) Before … a combine, even for a preliminary run, lubricate it according to the manufacturer's instructions.

3. Give your own definitions of the words:

Unthreshed, crop, chaff, grid, outlet

4. Insert prepositions if necessary:

a) To maintain an even flow of material through the ma-chine is possible … varying land speed according to crop volume.

b) In reasonable harvesting conditions, it should be about 5/16 in. from the front …. the cylinder.

c) This can be prevented by adjusting the fan air-inlet shutter so that the outlet blast is strong enough to keep the chaff … above the grain.

c) The concave is as important … separation as for threshing.

d) Straw-walkers should be used to separate only the minimum … grain.

5. Complete the questions:

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