Tractors and bulldozers:
The tractor is one of the most important road construction and construction machines, which has many applications. The primary purpose of the tractor is to push or pull all kinds of loads. On the tractor, all kinds of mechanical equipment can be installed, such as mechanical shovels, rippers, blades. bulldozers, lateral pipe rigs, tilting shovels, ditches, etc., besides tractors, they also use other things, such as pulling scrapers, wagons, etc.
The tractors are powered by diesel engines that are usually turbocharged, and there are standard and automatic transmission types, and their control is hydraulic control and automatic transmission. The tractors are generally of chain wheel and rubber wheel type.
Applications:
Bulldozers have many uses that can be mentioned below:
Leveling the ground and clearing it of bushes and tree stumps
Creation of primary roads in the mountains and rocky lands
Moving the mass of soil by pressing in large volumes
Help push the scrapers
Spreading the soil in the fields
Stacking soil next to the created streams
Leveling and cleaning the remains of construction operations
Maintenance of temporary dirt roads
Cleaning pits on the floor of mines
Types of tractors:
A - chain wheel tractors
There are different types of chain wheel tractors. These tractors are usually classified according to their size, weight and power. In many projects, the weight of a chain wheel tractor is important because the maximum traction force that a tractor can produce regardless of its engine power is the product of the weight. Due to the necessity of traction, the road surface on which they work is limited, the presence of chains allows the tractor to operate in areas with low compressive strength and suitable traction power.
B- Rubber wheel tractor
The rubber wheel tractor is made in order to be faster in pulling scrapers and similar works. These types of machines are available in two-wheel and four-wheel types. The two-wheel type must work with another machine such as a scraper so that it can maintain its balance. All the vulnerability of the tires of these machines when working in fields with sharp stones that cause the tire to be cut limits its use in these types of fields, although there are special wire chains to protect the tires that can be used to increase the friction of the tires with the surface of the ground.
2. Mechanical frames
Mechanical excavators are among the first modern construction machines that are used in earthworks. Mechanical excavators are mainly used for digging in the soil and loading it with trucks or trolleys or conveyor belts. Its powerful types are capable of digging in all types of soil except rocks and stones without initial destruction. is
Mechanical excavators consist of three basic parts: the carriage - the rotating chamber part on the carriage and the additional part in front of the machine.
Chariot or chassis:
Chassis is divided into two types: chain wheel chassis and rubber wheel chassis (truck)
1. It creates a stable and reliable chain wheel chassis for the upper rotating chamber and creates a very good mobility at the soil removal site. Also, due to the wide surface of the wheels, it creates a little pressure on the soil, which allows the user to work on loose soils in cases where there is friction depending on the type of soil. more is needed and if there is a problem of slippage, the role of the chain becomes important in the machine, instead, such shovels have low speed.
2. Rubber wheel chassis have a higher speed, so they are more useful for small jobs where the number of trips is high and the used road surface is solid.
The speed of the first type reaches 50 and the speed of the second type reaches 80 kilometers per hour.
Types of mechanical billers:
A- Excavator with reverse cup
This shovel is given several names, such as: curved shovel, back-bend shovel, and traction shovel.
These shovels are in two types, mechanical and hydraulic, and are suitable for digging.
B- Excavator with cable system
This mechanical excavator consists of a rotating cabin that is mounted on wheels and a shovel is attached to the front end of it. This shovel is in two types, mechanical and hydraulic.
C- Dragline shovel
The dragline excavator consists of a control room - crane - excavator cup and necessary cables to control different parts. The excavator is able to work at levels much higher and much lower than its support level and is used in all types of land. Its long arm is useful for digging and unloading the excavated materials, and the short cycle time is one of the advantages of this machine.
D- Crane
The crane consists of a steering room, a long mesh beam and the heart of the crane, and it is usually used for tying heavy objects and moving them. By connecting different devices to the end of the long mesh beam of the crane, other uses can be made. Cranes are of two types, mechanical and hydraulic, which are mostly hydraulic today.
3. Script
Scraper is a machine that carries out the loading, transporting and unloading of soil materials in medium and long distances alone.
The scraper consists of three main parts: the loading part (cup), the front wall of the loading part, the rear wall of the cup or the discharge wall of the cup, which is usually solid, has a replaceable cutting blade in the lower part, this blade penetrates into the soil during loading and cuts the soil into the cup. Guides . This part is movable and can go up and down in scrapers with a lift. The upper part replaces the front wall of the cup. The rear wall of the cup or the discharge wall has the ability to move backwards and forwards, which helps to discharge the bar by pushing the soil.
Types of Scripts:
Scrapers are divided into motorized and non-motorized types. Today, the non-motorized type is used less often. Most of the scrapers are single-axle and its balance and load weight are carried by the tractor connected to it. The tractors that pull these scrapers may have rubber wheels and chain wheels. Tractors are scrapers, which means that a single-axle tractor pulls a single-axle scraper. Scrapers that have two axles are pulled by chain tractors because such tractors cannot withstand standing loads, so they cannot break single-axle scrapers. Nowadays, chain wheel scrapers are rarely used. They are pulled by rubber wheel tractors and are subdivided into types
1. Single engine two axis
2. Triaxial
3. Dual differential
4. Two-engine scrapers (TANDEM-POWERED)
5. Elevating scrapers
6. PUSH - PULL
Two-axle single-engine scrapers use a single-axle tractor, and due to the balance issue, this tractor is unable to move without a related scraper. Three-axle scrapers are pulled by a tractor. It is a cup and it helps to process and transfer the scraped materials into the cup. In this type of scrapers, there is no need for an auxiliary tractor for loading due to the power it gives to the scraper lift.
4. Lodges
Without exaggeration, the loader is the most useful machine for construction and construction work. This machine is made in different industries because of its great performance and flexibility, and it can do many jobs by changing the cup.
Loader has many uses, some of which are:
Creating embankments, digging the basements of buildings, filling ditches and filling around pipes placed in canals, loading trucks, carrying concrete to the place of molds, and lifting and carrying construction materials.
A variety of accessories can be installed on the loader machine and it can be used for other purposes, such as snow plow, channel, pipe, crane, lift truck
Loader Types:
A - Rubber wheel loader
These loaders are made in small and very large sizes. Big rubber wheels give this type of loaders a lot of mobility and speed. The pressure on the ground by these tires is low, and this pressure can be changed by changing the tire inflation. However, there is a possibility of damage to these tires in any weather with sharp stones, including in wet and muddy areas. It is also difficult to operate a rubber wheel loader, of course, there are special wire chains to protect the tires, which can be used to increase the friction of the tires with the ground.
The back-breaking type that is used mostly in large loaders and has a chassis that connects the rear part of the loader to the front part by a joint. This joint mode increases the maneuverability and radius of rotation of the machine compared to fixed (non-articulated) chassis. In modern types of these machines, steering and hydraulic control systems are used. Electric is used for comfort and better performance of the driver. The steering system of these cars is of two types. In normal cars, the steering system works by the steering wheel and the movement of the wheels, but in the back-breaking type, the steering system works by hydraulic jack.
B - Chain wheel loaders
Chain wheel loaders work like rubber wheel loaders, with the difference that the low pressure they exert on the ground allows loaders with chain wheels to work in areas that cannot be used for rubber loaders. When working in areas with sharp rocks, there is no risk of tire tearing. Chain loaders are able to move on surfaces with a side slope of 35%, while this figure is 15% for a rubber wheel loader. Also, a chain loader can climb a 60% slope, while this figure is limited to 30% for a rubber loader. The speed of the chain loader is much lower than that of the rubber loader, for this reason, in cases where the distance of transporting materials and returning to the loading place is long, the efficiency of this machine is low compared to the rubber type.
C- Backhoeloader
These machines are actually small loaders that have an excavator on their back and are used for light work. All their general characteristics are the same as loaders and mechanical excavators. Due to the dual-purpose nature of this machine, this device is used in many small projects, especially if the project is related to digging ditches. be
As it was said, there is an excavator in the part of this machine, the power of this shovel also differs based on the angle of its reflection and the working radius of the arms. Manufacturing companies provide diagrams based on the power of the shovel in different situations based on the type of machines.
5. Games
Although equipment such as scrapers, conveyor belts and trains are used to transport earth materials, the most common means of transporting earth materials are trucks. The transportation of materials is relatively low. Trucks have great flexibility because the number of them used in a project can be increased or decreased to adjust the required capacity.
A- Normal trucks
These trucks are made in different types, one for on-road traffic and the other for off-road traffic (highway & off-highway trucks). Off-road trucks can be made in larger dimensions and with a capacity of several hundred tons. Each of them has different types, but its dumping type is used more than its general purpose. Dump trucks are used for The transportation of materials has great flexibility, and especially the type of smooth road, they are able to move easily in different projects. There are different types of dump trucks, for example, these trucks are sold in the market in diesel or gasoline, one or two-wheel drive and three-axle models.
B. Back-breaking trucks
As it is clear from the name of this type of trucks, they consist of two parts, the engine part and the tank part, which are connected by a joint. In fact, back-breaking trucks are special trailers for transporting soil materials, which are pulled by tractors. This unit is only designed to transport soil materials and transport materials. They are unloaded either from the back or from the floor of the wagon or from the sides. Some of these trucks have a long discharge channel which is mostly used for creating embankments. Compared to normal trucks, it increases in off-road roughness
6. Tarler
For leveling the ground and removing low and high elevations, different machines are used, but the most important tool for the operation of adjusting the slope and leveling the embankments and excavations and bringing the soil surface to the desired level (project line) is done by a grader. All drivers of road construction machines are of the opinion that working with a grader is better than other machines and a driver who has skills in using a grader can easily control and guide the rest of these machines.
7. Garder
The grader is used for adjusting the slope, shaping the slopes, leveling the range of embankments and excavations, digging and mixing and spreading the mixture of soil and bituminous materials. These machines are used in building roads and other construction operations. The blade of the grader has a replaceable edge, it can be placed in different situations compared to the machine, the angle of the blade can be changed so that the grader can be used to carry materials or dig up air. Excavated, but it causes the excavated material to overflow from the blade The front wheels can be bent to the sides and in this way it neutralizes the force due to the pressure of the inclined soil and helps in the rotation of the grader. While straight (mode A), the machine works in normal mode, while articulated mode (mode B), the grader can achieve a very small radius of rotation, while the rear wheel is firmly fixed on the ground, and at the same time, the machine can be engaged in digging fields and roadsides, etc., modern graders are equipped with control devices. They are automatic blades that are very accurate to adjust the tilt. The system of these devices, which is mostly hydraulic and electronic, is equipped with a sensitive device that follows a fixed surface or extension, and when necessary, it automatically moves the blade up and down to obtain the desired tilt. /p>
