The writing module

III. Writing exercises:

Exercise 1. Complete the sentences with the suggested words:

with; heavy; used as; has undergone ; of; added to.

The D9 is a series of ____ tracked-type tractors, propelled by Caterpillar tracks and usually ____ bulldozers. The D9 ____ several generations ____ engineering enhancements. Each new generation is denoted ____ an English letter ____ "D9".

Exercise 2. Fill in the table with words and expressions from the text:

	kinds of activity	attachments	models	types of vehicles
Example: caterpillar products range from				track-type tractors to hydraulic excavators
they are used in
a bulldozer is equipped with
the current versions are

Exercise 3. Compose a story on one of the topics (up to 100 words):

“The story of Caterpillar inc.”

“Caterpillar products”

“Current versions of the D9”

Lesson 6 the reading module

Read the text: The Caterpillar D10 and the Caterpillar D11

The Caterpillar D10 is a track-type tractor manufactured by Caterpillar Inc. (then called the Caterpillar Tractor Company). It was the first to use the elevated drive sprocket to improve durability, operator comfort, and ease of maintenance.

The Caterpillar D10 was the result of a need for a tractor larger than the Caterpillar D9.

The D9, with 354 kW (474 hp) of gross power and an operating weight of 49 tons, is in the upper end, but not the heaviest, of Caterpillar's track-type tractors, which range in size from the D3 57 kW (77 hp), 8 tons, to the D11 698 kW (935 hp), 104 tons.

At this time, competitors were building bulldozers that were more powerful than the D9. For example, the Fiat-Allis FA-41 track-type tractor had 525 horsepower (391 kW) at the time, while the D9 had around 450 hp (336 kW). The challenge was building a machine bigger than the others, especially in the drivetrain, and a group of engineers built a small machine from old lawnmower parts. This machine used a high-drive system with a sprung lower roller system. When the engineers hitched a Jeep to the machine it could pull the Jeep with ease.

The high drive (elevated sprocket) design eliminates the final drive system, which tended to break frequently. As the engine and drivetrain are mounted high in a traditional bulldozer, the half shafts from the differential exit above the drive sprocket, requiring a small gear on the end of the half shaft and another, larger one attached to the driven sprocket. The high-drive system eliminates the traditional final drive in favor of the planetary final drive, which is more effective at withstanding engine torque, since it spreads the forces over multiple gear teeth instead of a single tooth as in the traditional system. The disadvantage is that the track moves around one more sprocket, reducing track life. Caterpillar claims to have alleviated this with the SALT (Sealed and Lubricated Track), a permanently lubricated track system.

When the D10 was introduced in 1977, it was the most powerful track-type tractor, with 700 horsepower (522 kW). The Cat D10 could be ordered with blades up to a 19 foot (5.8 m) U-blade, and weighed in at around 190,000 lb (86,000 kg).

The Caterpillar D10 was manufactured at Caterpillar's Building SS in East Peoria, Illinois, until 1986. It was then replaced by the 770 hp (574 kW) Caterpillar D11. The D11 carried on the success of the high drive in large bulldozers, and the design eventually trickled down to the medium-size bulldozers, such as the D6.

It should be noted that today there is a Caterpillar track-type tractor known as the D10T. This machine is an upgraded version of the D10R track-type tractor, following in the vein of the other T-model releases: D8T and D9T.

The Caterpillar D11 series of tracked-type tractors are large conventional bulldozers. The Caterpillar D11 comes in two model variations, the standard D11R and the heavier D11R CD, and are second in size only to the Komatsu D575. The D11R CD has an 698 kW (935 hp) engine and gross weight of 113 metric tons.

D11s are primarily used for moving large quantities of material (dirt, rock, aggregate, etc.) short distances in relatively confined places. For example, they are often used in quarries. The D11 is most commonly found in use in large scale forestry, mining, and quarry operations.

D11s can be adapted for agricultural and rock ripping by fitting a ripper, a long claw-like device on the back of the tractor. Rippers can come singly (single shank) or in groups of two or more (multi shank rippers). Usually, a single shank is preferred for heavy ripping.

Ripping rock allows the ground surface rock to be broken into small, easy to handle and transport rubble which can then be removed so that grading can take place.