Disk tillers

These tools are designed for both tillage and seeding. They consist of a single gang of disk blades, 20 to 26 in. in diameter, on a common axle, all throwing the soil the same way. The common axle differentiates these tools from regular disk plows which have the disk blades tipped back, necessi­tating separate axles and bearings for each blade.

Disk tillers are made as small as two-blade models cutting 15 in. wide up to models cutting 20 ft wide. They are highly economical of power. Seeding boxes are available for some models, enabling seed-bed preparation and wheat seeding to be done in one operation.

The forces acting on a disk tiller are similar to those act­ing on.a plow except that the resultant lengthwise soil force on the blades is usually upward, requiring extra weight for penetration.

Trail-type disk tillers usually permit the angle of attack of the disk gang to be adjusted from 40 to 55°. In hard high-draft soil, penetration can be improved and width of cut de­creased by increasing the angle, while maximum width can be taken with less angle in loose easy-working soils. This adjustment is provided by changing the angle of the land wheel and the furrow wheels with respect to the disk gang.

Hitching principles are similar to those for mold-board plows. The centre of draft is at the centre disk blade slight­ly below the surface of the ground.

Disk tillers are necessarily built heavier than mold-board plows and wheel weights can be added for penetration in hard soil.

ВАРИАНТ 5.

I. Перепишите следующие предложения; подчеркните в каждом из них глагол-сказуемое и определите его видовременную форму и залог. Переведите предложения на русский язык. В разделе (б) обратите внимание на перевод пассивных конструкций.

а) 1. Many students come to the Academy by their own cars.

2. Laser devices will apparently make it possible to build extremely fast computer elements.

б) 1. A new experiment will be finished soon.

2. The material was looked for many scientific books.

II. Перепишите следующие предложения; подчеркните Participle I и Participle II и установите функции каждого из них, т.е. укажите, является ли оно определением, обстоя­тельством или частью глагола-сказуемого. Переведите пре­дложения на русский язык.

1. It’s not only an efficient tool for studying the physical properties of solids.

2. Having obtained the necessary results they stopped their experimental work.

3. When translated, his article was sent to the ICC.

4. All the houses made of wood were burning like paper.

III. Перепишите следующие предложения; подчеркни­те в каждом из них модальный глагол или его эквивалент; предложения переведите.

1. A mechanical feeding system should be completely automatically.

2. The water that comes to the field must get to the roots of every plant.

3. The best way of keeping the bull is to have a special barn for him.

4. Man could improve the soil using and discovering more kinds of soils.

IV. Перепишите и письменно переведите текст.

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