Ex. 5.3. Read the text carefully to learn about the configurations and functions of trenchers.

Trenchers

¹A trencher is a piece of construction equipment used to dig trenches, especially for laying pipes or cables, for installing drainage.

²Trenchers come in different sizes and may use a different digging implement, depending on the required width and depth of the trench and the hardness of the surface to be cut.

³A wheel trencher or rock wheel is composed of a toothed metal wheel. It is cheaper to operate and maintain and can cut harder ground than chain-type trenchers. Thanks to the wheel it is possible to work in hard or soft soils. They are also used to cut pavement for road maintenance and to gain access to utilities¹ under roads. Wheel trenchers may be mounted on tracks or rubber tires.

⁴Due to its design the wheel can reach variable cutting depths while keeping a constant soil working² angle with a relatively small wheel diameter. This reduces the weight and therefore the pressure to the ground and the height of the unit for transport.

⁵Last but not least advantage is offered by the cutting elements. These segments (6 to 8 depending on the diameter) which are placed around the wheel have the teeth which are more or less densified depending on the ground that they will encounter. These tools which can be easily changed manually allow the operator to adjust different cutting width on the same wheel. The teeth are placed in a semi spherical configuration in order to increase the removal of the materials from the trench. The teeth on the wheel are removable and made of high strength steel or cemented carbide. When the machine is under heavy use, the teeth may need to be replaced frequently, even daily.

⁶A chain trencher cuts with a digging chain that is driven around a rounded metal frame, or boom. This type of trencher can cut ground that is too hard to cut with a bucket-type excavator. This type of trencher can cut narrow and deep trenches. The angle of the boom can be adjusted to control the depth of the cut. To cut a trench, the boom is held at a fixed angle while the machine moves slowly. The excavated materials can be removed by a conveyor belt reversible either on the right or on the left.

⁷A micro trencher is a small rock wheel specially designed for work in urban area. It is fitted with a cutting wheel that cuts a microtrench with smaller dimensions than can be achieved with conventional trench digging equipment. The trench dimensions are widths ranging from about 30 mm to 130 mm, and a maximum depth of about 500 mm. These machines are sometimes radio-controlled. With a micro trencher, the structure of the road is maintained and there is no associated damage to the road. Owing to the reduced trench size, the volume of waste material excavated is also reduced.

⁸There are also portable trenchers. They may be used to install irrigation lines. These machines are lightweight (around 200 pounds) and are easily maneuverable compared to other types of trenchers.

⁹A trencher may be combined with a drainage pipe feeder unit and backfiller, so a drain may be placed and the trench filled in one pass.

Notes to the text:

Date: 2016-03-03; view: 823