月: 2024年1月

 

 

What Is a Tank Lorry?

A tank lorry refers to a cargo vehicle designed to transport liquids or gases in tanks.

The term “lorry” is essentially synonymous to “truck.” The transported goods include not only hazardous materials such as petroleum and chemicals specified by fire laws but also non-hazardous items like drinking water, milk, honey, raw concrete, and high-pressure gases.

The tank’s shape, usually cylindrical and essentially elliptical, ensures structural strength. However, tanks requiring pressure containment, such as those for gases, have a circular cross-section. The tank lorry’s tank volume is determined by the nature of its contents.

According to fire regulations, hazardous materials are limited to a maximum of 30,000 liters, high-pressure gases are limited to less than 18,000 liters, toxic gases excluding ammonia are limited to less than 8,000 liters, and non-hazardous materials do not have specific regulations.

Uses of Tank Lorries

Tank lorries are categorized based on their usage, such as powder and granule transport lorries, hazardous material lorries, and high-pressure gas tank lorries.

1. Powder and Granule Transport Lorries

Powder and granule transport lorries are used to transport powdered or granulated materials such as flour, sugar, feed, sand, and cement. If the transported materials are non-hazardous, and the driver holds the appropriate driving license based on the vehicle type and size, transportation operations can be conducted.

2. Hazardous Material Lorries

Hazardous material lorries are utilized for transporting materials classified as hazardous, such as petroleum, as defined by fire regulations. In addition to the appropriate driving license based on the vehicle type and size, a person with hazardous materials handling qualifications must accompany the driver. Transportation is also possible if the accompanying person, not the driver, holds hazardous materials handling qualifications.

3. High-Pressure Gas Tank Lorries

High-pressure gas tank lorries are employed for transporting compressed gases and liquefied natural gases, as stipulated by the High-Pressure Gas Safety Act.

Principles of Tank Lorries

The loading and unloading of tank lorries vary based on the nature of the cargo. Gases, for instance, are pressurized using a compressor and filled and discharged through pressure differentials. Pumps can be used for discharge and suction.

For liquids like petroleum, the lower part of the tank is pressurized from the facility side through piping to fill the tank under pressure, and gravity is used for discharge. In the case of common liquids, loading and unloading are possible by opening the top lid of the tank and discharging from the bottom outlet. Pumping may also be used for discharge.

Structure of Tank Lorries

1. External Structure

A manhole, with an injection port, is installed on top of the tank. When transporting hazardous materials, fire regulations mandate the installation of protective frames near the manhole.

At the bottom, there is a valve for discharging the load, which can be opened and closed using a handle. An air safety valve for pressure adjustment is installed externally to the tank. There are also measuring devices for calculating the amount of the load.

2. Internal Structure

The interior is divided by welded partition plates, allowing separate chambers for different liquids. To avoid confusion in withdrawing liquids, some vehicles have touch-panel controls that can be operated through computer systems. Since there is a risk of the liquid inside the tank swaying and causing the vehicle to overturn, wave-dissipating plates are installed inside the tank.

Types of Tank Lorries

Tank lorries come in various sizes, including large, medium, and small.

1. Large Tank Lorries

Due to restrictions on vehicle width, the tank of large tank lorries is designed to be slender. Generally, tank capacities range from 12,000 to 20,000 liters.

They are mainly used to transport petroleum products from refineries to gas stations.

2. Medium Tank Lorries

Medium tank lorries typically weigh between 3 to 4 tons, and their tank capacity ranges from 3,000 to 8,000 liters. A single compartment can hold up to 4,000 liters.

They are suitable for refueling heavy machinery, transporting diesel, kerosene, and heavy oil, as well as transporting feed and food from factories.

3. Small Tank Lorries

Typically weighing between 2 to 3 tons, small tank lorries have a tank capacity of 2,000 to 4,000 liters. Their smaller size allows them to navigate narrow residential roads easily, and they can transfer diesel or kerosene to households.

What Is a Dump Truck?

A dump truck is a construction vehicle primarily used for transporting materials such as soil, crushed stone, and industrial waste on construction sites.

At the rear of the dump truck, there is a loading platform for carrying materials. This platform can be raised and lowered, allowing for easy unloading by tilting the platform when raised. The term “dump” refers to the action of unloading materials all at once.

Uses of Dump Trucks

The primary use of dump trucks is in transporting soil generated from excavation and digging operations on construction sites. Additionally, they are employed for transporting crushed stone from quarries and clearing snow in snowy regions, among various other applications.

Depending on the type, dump trucks are also utilized for transporting items like mini hydraulic shovels or forklifts. The versatility of dump trucks allows for various applications based on their size and type.

Principles of Dump Trucks

The distinctive feature of raising the loading platform, known as the dump-up mechanism, involves engaging the PTO switch and lifting the dump lever to raise the platform. PTO, short for Power Take-Off, converts the engine’s power into operational power and is crucial for this function.

The loading platform is raised and lowered by extending and retracting hydraulic cylinders using hydraulic power. Lifting the lever raises the platform, while lowering the lever lowers the platform.

Structure of Dump Trucks

The structure of dump trucks consists of a chassis with a body superimposed on it. The chassis refers to the cabin (driver’s seat) and the vehicle frame (skeleton). The chassis requires high rigidity to support the mounted body.

The body of the dump Ttruck is the loading platform mounted on the chassis. The platform includes side-opening and rear-opening tailgates, as well as a spill prevention device called a spill guard to prevent materials from spilling over the top.

Types of Dump Trucks

In addition to the size of the vehicle, dump trucks come in various types suitable for specific applications.

1. Standard Dump Truck

This type is the most commonly seen dump truck capable of road travel. It comes in small, medium, and large sizes, often referred to as soil dump trucks or rear dump trucks.

2. Heavy Dump Truck

Used in large-scale construction sites such as dam construction, this enormous dump truck has a maximum payload ranging from 20 tons to over 300 tons. It is essential for large construction sites but prohibited from regular road travel.

3. Sand and Gravel Dump Truck

Designed for transporting materials other than soil, the sides and rear tailgate of this dump truck are higher. It is suitable for carrying relatively lightweight items such as feed, fertilizer, wood chips, and industrial waste. It is also known as a deep dump truck.

4. Loader Dump Truck

Besides tilting, this dump truck has a feature to slide the platform backward. This design allows the rear of the platform to touch the ground, making it useful for transporting mini shovels or forklifts.

It is a versatile dump truck suitable for transporting soil and machinery. It is also known as a slide dump.

5. Triple Dump Truck

This dump truck can tilt the platform in three directions: rear, left, and right, allowing for a broader range of unloading. While it has advantages in narrow construction sites and busy street construction sites, its complex structure makes it prone to breakdowns, and repairs can be costly.

6. L-Gate Dump Truck

Unlike the standard dump truck, this type has a rear gate that opens downward. While the standard dump truck opens the rear gate upward from the top pivot point, the L-Gate dump truck opens the rear gate downward from the bottom. The design allows for an open space without height restrictions, facilitating the unloading of large rocks and other items.

7. Reinforced Dump Truck

Designed for transporting hard loads like stones and rocks, this dump truck has a reinforced bed. The bed floor is strengthened, providing greater durability compared to a standard bed.

Other Information on Dump Trucks

1. License Requirements for Driving Dump Trucks

To drive a dump truck, a specific license is required, and the type of license varies based on the size of the dump truck. Additionally, there are rules and requirements for operating dump trucks.

Quasi-medium license (limited to under 5 tons) / Quasi-medium license

Under the Road Traffic Act, a quasi-medium license (limited to under 5 tons) or a quasi-medium license is required for driving a small dump truck.

Medium license

For driving a medium dump truck with a total vehicle weight of 5 tons or more but less than 11 tons (or under 8 tons in the case of an 8-ton limit), a medium license is necessary.

Large license

A large license is required for driving a large dump truck with a total vehicle weight exceeding 11 tons.

2. Display Number for Dump Trucks

To operate dump trucks categorized as large dump trucks with a weight exceeding 11 tons on public roads, approval from the Minister of Land, Infrastructure, Transport and Tourism is required. This involves obtaining a display number and affixing it to the vehicle. Additionally, the transport of loads exceeding the maximum payload is prohibited by law.

What Is a Crane Truck?

A crane truck is a vehicle equipped with the functionality of a crane, which can lift and horizontally move loads using power.

Known also as a mobile crane due to its ability to travel on roads, its major feature is the ability to be set up in various locations, allowing for the conducting of operations in optimal positions. With various vehicle variations and sizes, users can choose the type of vehicle according to the location and purpose. It is commonly used in civil engineering sites, demolition projects, construction sites, and is one of the familiar construction vehicles for the general public.

Uses of Crane Trucks

Crane trucks are used for various tasks such as moving loads and lifting or lowering materials in different locations. Their ability to self-propel and move to the work site is a key reason for their widespread use.

They play a vital role in various construction sites, job sites, rescue operations, event setups, and more. Their ability to operate in challenging terrains, soft ground, and confined spaces makes them highly valuable across different fields.

Principles of Crane Trucks

A crane truck is a vehicle with a crane apparatus mounted on a mobile chassis. The upper revolving body can rotate the entire vehicle left or right using a turning device. The elevation and extension of the jib (boom) on the upper revolving body are hydraulically operated.

Types of Crane Trucks

There are six main types of crane trucks, each capable of traveling and moving:

1. Truck Crane

Equipped with a revolving circle on the chassis and outriggers, this crane truck has a crane apparatus mounted on top. It has separate driver cabins for driving and crane operation. Available in various sizes, ranging from small to large, it can lift up to 20 tons.

2. Load-Carrying Truck Crane

This crane truck combines a crane apparatus and a loading platform on the chassis. Typically, the crane apparatus is mounted between the driver cabin and the loading platform. It is highly convenient as it can handle hoisting, loading, and transport operations in one unit. Usually, it has a lifting capacity of less than 3 tons, with crane operation either on the side of the vehicle or using remote control.

3. Wrecker Truck Crane

Used for towing accident vehicles and installing machinery in factories, this crane truck has a short jib length of 10m. It is equipped with a pintle hook and winch for towing purposes.

4. Rough Terrain Crane

A wheel crane with large tires, this all-wheel-drive crane truck is equipped with two axles for four-wheel drive. It has a small turning radius, making it suitable for use in narrow urban areas. Notably, it can stably operate on uneven or soft ground. It has a lifting capacity ranging from 4.9 tons to 70 tons, and with additional weights, some models can achieve capacities of over 100 tons.

5. All-Terrain Crane

A large crane truck capable of high-speed road travel and off-road movement. With a maximum of 8 axles and 16 wheels, this all-terrain crane can achieve both multi-axle drive and steering, ensuring maneuverability in tight spaces. It can deliver significant lifting capacity even in confined work areas.

6. Crawler Crane

A crane truck with a crawler running system. Crawler-type cranes have a wide ground contact area, resulting in low ground pressure, allowing them to travel on soft ground. While their travel speed is slow, around 1 to 3 km/h, they cannot travel on public roads and are transported on trailers.

Other Information on Crane Trucks

Licenses Required for Operating Crane Trucks

To operate and handle a crane truck, individuals need to undergo training tailored to the specific crane truck they will use. This includes:

• Special education for driving mobile cranes
• Small mobile crane driving skills training
• Mobile crane operator’s license
• Rigging skills training

Additionally, for on-road travel, licenses such as a medium-sized license, large-sized license, or large-sized special license are required based on the vehicle’s size.

What Is a Tractor?

A tractor is a vehicle designed to tow non-powered implements.

Primarily used in construction and agriculture, tractors vary in size and horsepower depending on the implement being towed. Trailers for transporting goods are also a type of tractor, characterized by the independent existence of the towing vehicle and the cargo-carrying section.

Fuel selection is adaptable based on the application, with compatibility for diesel or gasoline. By changing the implement, a single tractor can perform various tasks. Particularly in agriculture, tractors have been in use since the early 19th century, and their development has continued to the present day.

Uses of Tractors

1. Agriculture

In rice or crop cultivation, horsepower is selected based on the size of the farmland. The common usage involves the combination of a tractor and a specific implement.

Various implements have been developed in response to the numerous farming processes and are widely used. In agriculture, where challenges such as an aging population and a shortage of successors are present, efficiency in operations becomes a significant theme, with tractors playing a crucial role.

Specific agricultural applications include:

Plowing

Implements such as rotaries or plows are used for field cultivation. Rotaries rotate rows of tines to till the soil, while plows turn the soil in an up-and-down motion, mixing and creating a base soil structure.

Seeding

Seeding is performed using a seeding machine. Models vary based on seed size, aiming to optimize the seeding depth, a critical factor affecting crop growth.

Spraying

Boom sprayers are utilized for widespread pesticide and chemical application. This device sprays agents from boom-style nozzles while the tractor moves, ensuring even coverage over crops. The development of mechanisms to reduce chemical loss is ongoing, with consideration for both environmental impact and adherence to pesticide regulations.

Fertilizing

Lime spreaders and broadcasters are used for fertilizer application. Many lime spreaders employ power take-off (PTO) drives in various models, allowing for uniform fertilizer spreading, especially with powdered or pelletized fertilizers. Broadcasters, using the centrifugal force of a built-in rotating disc, can cover a wide area but may have challenges in precision. Both types are not suitable for liquid fertilizers.

Harvesting

Combines or harvesters are employed for harvesting operations. These machines can separate edible parts from unwanted portions, and some allow for external discharge.

2. Construction Operations

To enhance the efficiency of construction operations, various implements have been developed. Tractors can handle tasks ranging from excavation to soil transport and paving, expanding their versatility.

3. Forestry

In forestry, tractors are used for securing footholds and transporting thinned wood. Models capable of progressing on slopes and challenging terrains are highly valued.

4. Logistics

By utilizing trailers, tractors can cover long distances and transport large quantities. The cargo-carrying containers are often interchangeable between different tractors, contributing to smooth logistics operations. To facilitate connection and disconnection, the tractor is equipped with a connector called a coupler, while the trailer features a large pin known as the kingpin. This setup eliminates the need for unloading, reducing the burden on workers. Tractors can also transport automobiles and heavy machinery, making them cost-effective.

Principles of Tractors

Due to their structural design with implements attached to the rear, tractors tend to have a rearward-biased center of gravity. Countermeasures include attaching weighty components to the front to adjust the balance. To navigate challenging terrains, tractors are equipped with crawler tires.

Other Information on Tractors

Unmanned Tractors

In response to labor shortages in agriculture, expectations for unmanned tractors are significant, and various companies are actively developing them. Field trials, including pesticide spraying using flying drones, are conducted, emphasizing the diversification of roles and the utilization of AI.

Current challenges include the deployment of infrastructure enabling high-speed data communication, cost issues related to the tractor itself, and legal interpretations during on-road travel. Nevertheless, the market size is expanding yearly, urging the realization of “smart agriculture.”

What Is a Refrigerated Truck?

A refrigerated truck, also known as a refrigerated van, is a type of truck equipped with a refrigeration unit in its cargo compartment, allowing continuous cooling temperature.

Refrigerated vans with similar functionalities have insulated cargo compartments that can temporarily maintain a specific temperature. The development of refrigerated trucks in Japan began in 1958, driven by the demand for food transportation, including milk and ice cream, from U.S. military bases.

The technology of refrigerated trucks has evolved, and modern versions feature computer-controlled refrigeration units, enabling more precise temperature management. Additionally, refrigerated trucks with fuel-efficient hybrid systems have been developed, contributing to environmentally conscious transportation.

Uses of Refrigerated Trucks

Refrigerated trucks are divided into medium-temperature and low-temperature categories based on the storage temperature. They are used for transporting food and other items to supermarkets, convenience stores, restaurants, and more. Medium-temperature refrigerated trucks maintain temperatures around -5°C, suitable for transporting fresh food, while low-temperature refrigerated trucks, capable of storing items at -15°C or below, are ideal for transporting ice cream and frozen food.

Refrigerated trucks are also utilized for transporting biological tissues, blood products, and play a crucial role in various industries. On the other hand, trucks with insulated cargo compartments, known as chilled trucks, are used for transporting items like fresh food, school meals, and bento with less stringent temperature control requirements and shorter delivery times.

Structure of Refrigerated Trucks

The cooling system in a typical refrigerated truck has a basic structure similar to a car’s air conditioner and consists of five main components:

1. Compressor

Utilizes the engine’s power to compress the refrigerant into a gas, then sends it to the condenser.

2. Condenser

Liquefies the high-temperature, high-pressure gas sent from the compressor by cooling it with outside air, then sends it to the expansion valve.

3. Expansion Valve

Reduces the pressure of the high-pressure liquid refrigerant received from the condenser, turning it into a mist and sending it to the evaporator.

4. Evaporator

Vaporizes the mist-like refrigerant liquid received from the expansion valve, absorbing surrounding heat, and circulates it forcefully with a fan.

5. Control Panel

An apparatus for adjusting the temperature inside the refrigerated compartment. It allows temperature management of the refrigerated compartment from the driver’s seat. Additionally, refrigerated trucks use insulation materials such as polyurethane foam or polystyrene foam on the walls, ceiling, and floor to maintain a constant temperature inside and minimize cold air leakage.

Types of Refrigerated Trucks

Refrigerated trucks are categorized into three types based on the cooling method: mechanical, liquid nitrogen, and cold storage.

1. Mechanical Type

Uses the engine’s power similar to an air conditioner, allowing precise temperature control. Most refrigerated trucks adopt this method.

2. Liquid Nitrogen Type

Uses liquid nitrogen, a commonly used cooling agent, to achieve temperatures as low as minus 40 degrees Celsius. Suitable for rapidly cooling items that require it.

3. Cold Storage Type

Utilizes electricity to cool the refrigeration unit’s cooling plate. When not in use for transportation, the refrigeration plate in the cargo compartment is frozen, and during transportation, the frozen plate provides the necessary cooling. This type is more energy-efficient and environmentally friendly.

How to Choose a Refrigerated Truck

1. Payload Capacity

Choosing a refrigerated truck with an appropriate payload capacity is crucial. Insufficient payload capacity can lead to increased transportation frequency, higher fuel and labor costs, and decreased operational efficiency. On the other hand, significantly lower payload capacity than the standard may result in unnecessary expenses such as higher fuel costs. When purchasing a refrigerated truck, it is essential to select one that aligns with the daily payload capacity requirements.

2. Cooling System Method

For mechanical-type refrigerated trucks, choosing between engine-direct and sub-engine systems is a key decision point. The engine-direct system, being lighter, offers fuel savings but cannot cool when the engine is off. The sub-engine system, with a dedicated engine for the refrigeration unit, provides high cooling capacity even when the main engine is off. However, it is heavier and less fuel-efficient.

When selecting a refrigerated truck, careful consideration of the intended use and whether a sub-engine is necessary is crucial.

3. Travel Distance and Internal Temperature

The appropriate type of refrigerated truck depends on the transportation distance and the type of cargo. If the cargo does not require an extremely low temperature, there is no need for a truck that can switch between freezing and refrigeration. For longer distances, it’s essential to consider energy-efficient models, such as those with sub-engines that allow cooling during breaks.

When purchasing a refrigerated truck, it is vital to factor in the transportation distance and internal temperature requirements to make the right choice.

What Is a Crane?

A crane is a mechanical device that utilizes power (excluding human power) to lift and horizontally transport loads. It refers to both stationary and mobile types within a limited range. The definition of a crane includes two aspects: lifting loads using some form of power other than human power and horizontally transporting the lifted load (which may involve human power). There are no specific requirements for unloading the load.

Additionally, a mobile crane, such as a crane truck, which has an integrated engine and can move to unspecified locations, is referred to as a mobile crane. However, according to the crane and other safety regulations based on the Labor Standards Act, cranes and mobile cranes are categorized as separate mechanical devices.

Uses of Cranes

Cranes are widely used in various work sites and industries, including construction sites, ports, rooftops of buildings, manufacturing plants, and transportation. Different types of cranes are designed to efficiently perform tasks according to specific locations and use cases.

These mechanical devices are commonly employed for tasks such as transporting construction materials and components, as well as loading and unloading cargo, where manual labor alone is insufficient.

Features of Cranes

Advantages

The advantages of cranes include the ability to lift and transport heavy loads that cannot be moved by human power alone. This allows for the safe and efficient lifting and movement of heavy objects in a short amount of time, making it possible to carry out operations in locations where other machines cannot operate, such as during the construction of tall buildings.

Disadvantages

The disadvantages of cranes include the fact that, in addition to those capable of self-propulsion, there are also large cranes that require assembly and installation. In such cases, the time and cost of installation are incurred, and a vast space is often required.

Types of Cranes

Cranes come in various types depending on their intended use. Representative types include:

1. Truck Crane

A truck crane is a crane mounted on a truck, allowing it to move on roads for easy transportation. It is used to lift loads of less than 3 tons, and there are tow trucks with mounted cranes.

2. Rough Terrain Crane

A rough terrain crane, equipped with large tires, can travel on mild soft ground and uneven terrain. With four-wheel drive and four-wheel steering, it is suitable for operations in narrow alleyways.

3. All-Terrain Crane

An all-terrain crane combines the ability to travel on highways like a truck crane and move on mild soft ground and uneven terrain like a rough terrain crane. Some can lift over 1,000 tons, demonstrating significant power even in tight spaces.

4. Crawler Crane

A crawler crane can travel on soft ground and uneven terrain due to its crawler-type traveling mechanism. It can operate in places where tire-based cranes cannot access. However, its drawback is a slower traveling speed.

5. Gantry Crane

A gantry crane is a massive crane device installed on the quay of a port. It is used for unloading and loading containers from cargo ships, playing an essential role in maritime transport.

6. Unloader Crane

An unloader crane is a dedicated crane used in ports to lift coal, minerals, grains, and other cargo from ships to the shore. There are types that use cranes and those that use conveyors for unloading.

7. Overhead Crane

An overhead crane travels on a runway installed near the ceiling of a factory. It is used for transporting large components and other items that cannot be moved by human power alone.

8. Jib Crane

A jib crane lifts loads using a wire and hook extended from the tip of its arm. Recognizable by its long arm, the arm portion is called the “jib.” Large cranes installed on the rooftops of buildings are also jib cranes.

9. Stacker Crane

A stacker crane is used in warehouses and factories for storing and retrieving cargo and parts. Rails are installed on the floor or shelves, and cargo or parts are moved on these rails.

10. Cable Crane

A cable crane is used for transporting materials and pouring concrete during dam construction. It has a structure similar to a cable car and is suitable for long-distance transportation. In addition to dam construction, it is also used in river improvement projects and bridge construction.

Other information on Cranes

1. Special Education for Crane Operation

Completion of special education for crane operation allows the operation of cranes with a lifting capacity of less than 5 tons and the operation of crane cars with a capacity of 5 tons or more.

2. Crane and Derrick Operator License

• Crane and Derrick Operator License (Unlimited)
  Allows operation and control of cranes and derricks with a lifting capacity of 5 tons or more.
• Crane and Derrick Operator License (Crane Only)
  Allows operation and control of cranes with a lifting capacity of 5 tons or more.
• Crane and Derrick Operator License (Floor-Controlled Crane Only)
  Allows operation and control of floor-controlled cranes with a lifting capacity of 5 tons or more. It also allows the operation and control of cranes with a capacity of less than 5 tons.

What Is a Grader?

A grader, also known as a motor grader, is a construction machine used for tasks such as leveling roadbeds and pavements in construction sites and road construction, as well as for snow removal operations.

Equipped with a blade of 3.1m to 4.3m in width mounted at the bottom center of the machine, its angle and height can be adjusted to perform delicate and precise leveling operations. A grader that is self-propelled by an engine is referred to as a motor grader, and those used for snow removal operations are known as snow graders.

In addition to the blade, graders can be equipped with various working attachments such as a snow plow, ripper, and scarifier. They are indispensable construction machines in large-scale construction sites and snow removal operations.

Uses of Grader

Graders are primarily used for leveling large construction sites, leveling roadbeds and pavements in road construction, and preparing the subgrade for asphalt paving. They are mainly employed for spreading and leveling work. The blade, raised in a bank-up position, can also be used for tasks like cutting slopes.

While bulldozers also perform leveling work, they are suited for different locations and purposes. Bulldozers are suitable for leveling large amounts of soil and soft ground, whereas graders are used for precise leveling tasks such as road construction, where high accuracy is required.

In large construction sites, it is common to use bulldozers for rough leveling followed by graders for finishing leveling. Moreover, graders are employed as snow removal machines in regions with snowfall.

Principles of Grader

Similar to other construction machines, graders operate using hydraulic power. Operators adjust the height and tilt of the blade by manipulating multiple levers in the control cabin. Presently, graders are available with joystick controls, eliminating the need for a steering wheel.

Structure of a Grader

The grader has a structure with a long boom extending forward, equipped with a blade (moldboard) suspended from it. The rear section contains the operator’s cabin and houses the engine. The tire configuration is 6 wheels on 3 axles, with 2 wheels at the front and 4 wheels at the rear.

While the blade is angled for operations, it generates a reactive force when under load. To prevent the front wheels from swaying and ensure a straight path, there is a leaning mechanism that tilts the front wheels left and right, maintaining straight-line stability.

How to choose a Grader

When selecting a grader, one considers the intended use, choosing based on blade width and engine output. For earthmoving, a grader with a blade width of 3.1m to 3.7m is used, while for snow removal, the standard is a grader with a blade width of 3.7m to 4.3m. Graders have a much smaller lineup compared to other construction machines.

Other information on Grader

1. Types of Attachments

In addition to the blade, various working attachments such as a snow plow, ripper, and scarifier are available. These attachments enable a wide range of operations.

Snow Plow

Attached to the front of the machine, it is used for deep new snow and snowdrift removal. There are angling plows that can adjust the discharge direction to the left or right and V-plows that can discharge snow to the left or right.

Ripper

Attached to the rear of the machine, it is a large-toothed attachment used to crush the ground or rock.

Scarifier

Attached to the center of the machine, it is a wedge-shaped attachment used for crushing and excavating hard ground.

2. License Required for Driving

While graders are used for tasks such as leveling land on roads and construction sites, a large special license is required to drive them on public roads. Moreover, for operational use, according to the Labor Standards Act, a qualification as a vehicle-related construction machinery operator is necessary. Both a driving license and qualification are required for grader operation.

What Is a Finisher?

A finisher, also known as asphalt finisher, is a machine used for paving asphalt.

It is a construction machine used when leveling the ground, such as roads, and laying asphalt. It can spread the materials that form the basis of asphalt to a specified width and thickness, compacting the ground to increase its strength.

Uses of Finisher

The primary application of an asphalt finisher is in the final stage of road construction, which involves paving asphalt. After the foundation is completed, the finisher is used to evenly spread asphalt at a consistent thickness and width.

The classification of asphalt finishers is based on the screed width. In Japan, where roads with a paving width of 6m or less are common, the use of medium-sized units is prevalent. Overseas, where roads with widths of 9m or 12m are encountered, larger units are utilized.

Structure of Finisher

Asphalt finishers can be broadly categorized into four parts.

1. Hopper

This is the box-shaped part where asphalt mixtures are stored. The left and right sides of the hopper can be opened and closed, and it contains a conveyor to transport the asphalt mixtures to the rear of the machine.

2. Tractor

This part pulls the machine’s body.

3. Screed

The screed is responsible for leveling and smoothing the asphalt. It uses screws to even out the thickness of the asphalt mixture spread by the machine. Screed widths vary, with smaller ones at 0.8m and larger ones reaching up to 16m, influencing the pavement width that can be constructed.

Additionally, the screed may be equipped with a vibrator to compact the asphalt mixture and a gas burner to prevent the asphalt from solidifying.

4. Engine

The engine serves as the power source for the entire vehicle, using diesel fuel.

Types of Finishers

Asphalt finishers are categorized into crawler-type and wheel-type based on the difference in driving wheels.

1. Crawler-type

Crawler-type finishers use caterpillars in their running mechanism. They cannot be driven on public roads since they cannot acquire license plates. While they have a lower traveling speed compared to wheel-type finishers, their large contact area provides excellent stability, making them suitable for use on steep slopes or soft ground.

2. Wheel-type

Wheel-type finishers use tires in their running mechanism. They fall under the classification of large special vehicles and can be driven on public roads once license plates are obtained.

Wheel-type finishers are self-propelled, eliminating the need for transport vehicles like those required for crawler-type finishers. While their stability is inferior to crawler-type models, recent wheel-type finishers come with four-wheel drive, reducing tire slippage and enhancing stability.

Other information on Finishers

1. License Requirements for Operation

Asphalt finishers are classified as special vehicles. To operate a wheel-type asphalt finisher, a “Small Special License” or “Large Special License” is required, depending on the size of the vehicle. However, for a small special vehicle license, it is possible to operate if one already holds a regular driver’s license. For small special vehicles, the vehicle must meet specific criteria: length under 4.7m, width under 1.7m, height under 2.8m, and a maximum speed of 15km/h.

For large special vehicles not meeting the above criteria, the maximum speed is limited to under 35km/h.

2. Qualifications Required for Paving Work

Two types of qualifications are required for pavement work using asphalt finishers:

• Vehicle-related construction machinery skills training (for leveling, transportation, loading, and excavation)
• Construction machinery construction engineer 2nd Class (Type 5)

To perform pavement work using an asphalt finisher, one must hold either of the above qualifications. The vehicle-related construction machinery skills training can be obtained by undergoing training sessions.

What Is a Road Roller?

A road roller is a construction machine used for compacting the ground during construction projects.

Named for its use of a cylindrical roller attached to the vehicle body to compact roads, it is also known as an iron wheel roller or smooth roller. Official documents from government agencies may refer to it as a compaction machine.

Uses of Road Roller

Road rollers are utilized in various applications such as foundation construction and roadwork, including asphalt compaction and ground leveling.

By traversing with a heavy vehicle body, they compact the ground. Different types, including tandem and tire rollers, must be selected based on the location, environment, and requirements for compaction.

In recent years, construction cases employing Information and Communication Technology (ICT) have emerged. Real-time monitoring of compaction status and autonomous operation enhance quality and operational efficiency.

Principles of Road Roller

A road roller is one type of compaction machine. It compacts the soil by compressing the space within the soil through the machine’s weight and the wheel load of the roller. Tire rollers, aside from wheel load, achieve optimal compaction by adjusting tire air pressure to alter ground pressure according to soil type and work requirements.

Some compaction machines utilize vibration and impact, contributing to a smoother finish by choosing the appropriate machine for the application.

 

What Is a Bulldozer?

A bulldozer is an earthmoving machine used for excavation, embankment, leveling, snow removal, and various civil engineering tasks.

Bulldozers exert significant force to push and move large volumes of soil, rocks, making them indispensable on construction sites. By reducing the gear on the rotating side connected to the engine and increasing the gear that turns the wheels, bulldozers generate substantial power.

The origin of the term “bulldozer” has various theories. One suggests that in the United States, the appearance of bulldozers led to bulls becoming so idle (doze) that they were named “Bulldozer.” However, since horses and mules were more commonly used than bulls, a prevailing theory suggests that it evolved from the slang “Bull’s dose,” meaning “to forcefully push forward.”

Uses of Bulldozer

Bulldozers are used in civil engineering, dam construction, land development, and more. Due to their frequent use in large-scale projects like bamboo forest clearance, there is a higher demand in developing countries where land development is still in progress compared to advanced nations.

Moreover, bulldozers come in various types, including amphibious models for construction in places inaccessible to dredging ships and remote-controlled bulldozers for hazardous disaster sites. Recently, ICT bulldozers equipped with GPS and 3D design support operators with automatic blade control, promising further improvement in operational efficiency.

Features of Bulldozer

One prominent feature of bulldozers is their blade. Applying weight to the front end of the blade allows for excavation, earthmoving, and leveling. The blade is attachment-style, allowing it to be changed based on the intended use.

Another notable feature is the crawler. The crawler consists of metal or rubber-like long plates connected around the drive wheel, enabling the bulldozer to travel even on rough terrain.

Bulldozers are categorized as dry-land and wetland types, each with different crawler shapes. Wetland models have wider crawlers to lower ground pressure, and they use special triangular-shaped shoes to facilitate construction on soft ground.

Types of Bulldozers

There are several types of bulldozers based on the blade type and additional equipment called a ripper.

1. Classification by Blade

Straight Dozer
The blade is attached perpendicular to the centerline of the body. It has substantial excavation force and is used for general soil excavation, compaction, and soft rock excavation.

U-Blade
Both sides of the blade are curved forward, allowing for the transport of a large amount of soil.

Angle or Power Angle Dozer
Some bulldozers are equipped with features called angle or power angle. Angle dozers can attach blades at an angle to either side, while power angle dozers have hydraulic features that tilt the blade left or right. These can be used for a wide range of tasks such as excavation, backfilling, ditching, and leveling.

Rake Dozer
A type of attachment for bulldozers used in large-scale landscaping to remove large rocks.

Two-Way Dozer
Capable of both front pushing and pulling materials, often used for grain transport ships or for cargo handling inside ships.

2. Classification by Ripper

Multi-Shank Ripper
A standard ripper with three tines. The number of shanks can be adjusted based on the hardness of the bedrock.

Giant Ripper
A ripper with one long shank, suitable for deep digging.

Parallel Link Ripper
A ripper with one shank and a parallel link mechanism to maintain a constant penetration angle even with varying depths.

Hinge-Type Ripper
A simple and cost-effective ripper with a disadvantage of changing shank angles with penetration depth, making it less commonly used today.