月: 2023年1月

What Is a Vertical Machining Center?

A vertical machining center is a machining center that evolved from a vertical milling machine. The axis (spindle) that rotates the tool is mounted vertically, and cutting processes such as milling and drilling can be performed with a single machine.

Because they are versatile, easy to use, space-saving, and inexpensive, they are frequently used in machining centers.

A vertical machining center moves the workpiece (material) or tool along the X, Y, and Z axes, making machining from the top the standard practice. There are also 5-axis machining centers that can rotate the workpiece using the X and Y axes as rotation axes.

Uses of Vertical Machining Centers

Vertical machining centers are used for machining metals, plastics, ceramics, and other materials, because they can handle all types of cutting workpieces, including milling, end milling, boring, drilling, and tapping.

They are used for die and mold machining, taking advantage of their ability to process relatively large parts due to the large space available for workpiece placement and their strength in top-side machining.

Since it is easy to set up workpieces and fix jigs, it is often used for high-mix, low-volume production machining where workpieces are frequently changed.

Principle of Vertical Machining Centers

Vertical machining centers can be installed in a small space because the main spindle is located on the top and the footprint of the vertical machining centers are small in relation to the machining area. Vertical machining centers also have the advantages of a simple structure, low cost, and easy delivery of cutting fluid to the workpiece machining surface.

One demerit is poor chip discharge. Chips generated when cutting from the top tend to remain on the workpiece, and these chips can be caught in the machining operation, leading to scratches on the machined surface and damage to the tool. In addition, since it is difficult to introduce a pallet changer that automatically changes workpieces, workpieces cannot be installed automatically and machined continuously, making the machine less suitable for mass production. If the work to be machined is large in volume, a horizontal machining center with the spindle oriented horizontally is suitable instead of a vertical machining center.

Also, the small size of this equipment limits the size of workpieces that can be machined. For large workpieces that cannot be machined with a vertical machining center, a double-column machining center is suitable.

What Is a Cooling Tower?

A cooling tower is a device used to cool a certain fluid. The target fluid can be exhaust gas, process water, circulating water, etc. The most commonly used type of cooling tower is the cooling tower for circulating water. The most commonly used type of cooling tower is for cooling circulating water, which is widely used because of its simple structure.

Cooling towers range in size from relatively small ones used for air conditioning to huge ones as large as a skyscraper used for cooling an entire plant.

When cooling water is cooled by a cooling tower, there is a risk of bacteria growing in the circulating water, which can be harmful to human health, so additives are generally injected to control water quality.

Uses of Cooling Towers

Cooling towers are used in various aspects.

In everyday life, they are used for air conditioning in large commercial facilities and for freezers in large warehouses. As the size and capacity of cooling systems increase, cooling towers are used.

In industrial applications, cooling towers are used to cool the inlet air of gas turbines in power plants and to cool exhaust gases in process plants. In industrial applications, cooling towers are used when it is more rational to cool an object, and the recovered heat is often reused from the viewpoint of energy conservation. The most commonly used heat transfer medium is tap water.

Principle of Cooling Towers

Cooling towers are a type of heat exchanger. In principle, the cooling object is cooled by exchanging heat through the application of air to the circulating cooling object.

Cooling towers can be broadly divided into two types: open type and closed type.

In the open type, heat is extracted by direct contact with the cooling target with the outside air inside the cooling towers. This type is used when the cooling target is a harmless liquid.

The open type is often used for cooling circulating water and consists of a water storage tank, circulation pump, water supply unit, and chemical injection unit, and has the following structure: Water in the water storage tank is circulated by the circulation pump and constantly introduced into the cooling towers. In the cooling towers, the water is heated by the atmosphere to keep the temperature in the storage tank at a constant low level. Since water evaporates little by little in the cooling towers, the water level in the storage tank is kept constant by the water supply system. Bacteria can grow in water storage tanks due to prolonged circulation, so the water is sterilized by a chemical injection system. The same mechanism is used for cooling towers that do not circulate drinking water.

In enclosed cooling towers, the cooling target is cooled by indirect exposure to the atmosphere through conduit coils or other means. Enclosed cooling towers are used when it is not desired to open the cooling object to the atmosphere.

What Is a Cooling Device?

A cooling device is a device that cools the temperature of a certain space.

In the past, forced air circulation by fans and the use of vaporization heat by sprinkling water were used to lower the temperature of a space. After electricity became widespread, fans with simple structures became popular.

In recent years, air conditioners have become the most common type of cooling device. Air conditioners are devices that exchange heat between space and outside air. They have become widely used in homes because they can be used for both cooling and heating by rotating the compressor in the opposite direction.

Uses of Cooling Devices

Cooling devices are widely used in industrial and residential applications.

Room air conditioners are a typical example of home use. In recent years, one household has been equipped with at least one room air conditioner. Refrigerators can also be considered home cooling devices. Although the shape is different, the mechanism is the same as that of room air conditioners.

For industrial use, there are examples of refrigerators that use antifreeze solutions. They are used for cooling processes and heat-generating equipment. Industrial cooling devices use dozens of times more environmentally hazardous refrigerants such as chlorofluorocarbons than room air conditioners, so they are subject to legal obligations such as periodic inspections, installation notifications, and installation permits.

Principle of Cooling Devices

First, consider the mechanism of a fan or blower as a forced-air cooling device. A fan sends out cool air by turning an impeller with a motor. It serves as a cooling device because the air temperature around an object does not rise.

Next, we consider air conditioners. An air conditioner consists of a compressor, a heat exchanger, and a blower installed outside the room. This is generally called an outdoor unit. A heat exchanger and a blower are also installed indoors. This is generally called an indoor unit. Refrigerant, which repeatedly vaporizes and liquefies according to pressure fluctuations near normal temperature and pressure, is sealed in the air conditioner, and cooling is performed by vaporization heat when the pressure in the system is fluctuated by a compressor. When the pressure of the refrigerant is increased outside the room, it liquefies and releases heat. The released heat is vented to the atmosphere by an outdoor blower. The liquefied air expands and vaporizes inside the room, removing heat from the room. The indoor blower circulates the cooled air throughout the room.

Next, a chiller is a device that maintains room temperature below 0°C. Its mechanism is similar to that of an air conditioner, designed to reduce indoor temperatures. However, the cooling speed is not fast enough for the blower, and the temperature of the outdoor unit rises too high. Therefore, the water-cooling method is sometimes used. Instead of discharging into the atmosphere, water with high thermal conductivity is used as a refrigerant. The water is cooled by a device called a cooling tower. If indoor air is also averse to solidification, antifreeze is circulated.

Cooling devices generally use a heat exchange system with a compressor, but Peltier effect cooling devices also exist. This cooling device uses a substance that becomes cold when an electric current is applied. They are rarely sold as compact cooling devices.

What Is a Zero Flux Current Transformer?

A zero flux current transformer is a device used to detect the current value called the zero phase current in a three-phase AC power supply.

The sum of the vectors of the currents flowing in each phase of a three-phase AC power supply is normally symmetrical and thus zero, but when a ground fault current flows, the balance is disturbed and a non-zero value is obtained.

In the event of a ground fault, a zero flux current transformer is activated to immediately disconnect the fault location from the surrounding electrical circuit.

For this reason, they are built into RCDs in advance and constantly play a role in detecting accidents.

Uses of Zero Flux Current Transformers

When an electrical circuit in an electrical facility is electrically connected to the earth, a large current flows into that point as an earth fault current, and there is a risk of a serious accident.

Zero flux current transformers are used to prevent this, and when a ground fault current is detected, the ground fault point is immediately disconnected from the surrounding area.

Although also used for low-voltage general instrumentation, the role of the zero flux current transformers becomes more important as it is essential for higher voltage circuits, where the severity of the accident may be greater.

Principle of the Zero Flux Current Transformers

In a three-phase AC power supply, if the currents flowing in each of the three phases are equal and symmetrical, the sum of their vectors is zero.

The average value of the sum of the vectors is called the “zero-phase current,” and in the symmetrical form shown above, the zero-phase current is zero.

If a ground fault current flows in any of the three phases, the three phases are unbalanced and the zero-phase current is not zero. This allows for the immediate detection of ground faults.

“Zero flux current transformers” are a device that detects this kind of zero-phase current in a three-phase AC power supply.

Like ordinary current transformers, it has a structure in which a coil is wound around a circular iron core, and a conductor penetrates through the center of the ring.

However, while a normal current transformer has only one through conductor, zero flux current transformers have three through conductors for each of the three phases.

If the current balance of the three phases is disturbed for any reason, a secondary current flows momentarily through the coil, and this is detected as a ground fault.

It is often built into RCDs together with relays and circuit breakers and plays an important role in preventing leakage currents that can lead to accidents, fires, and other disasters.

What Is a Funnel?

A funnel is a device used to transfer liquid from one container to another.

It is mainly used in chemical experiments. The most common and familiar example is a glass funnel. Its shape is an inverted triangle with a wide opening at the top and a narrower opening at the bottom. At the bottom end is a thin tube.

Uses of Funnels

Funnels are used in two main ways: First, they are used to move liquids. Pouring a liquid directly from one container to another may cause spillage. This is fine for water or other liquids, but for hazardous liquids, a problem arises.

The second use is to separate liquids and solids in suspension. The funnels are lined with filter paper, and liquid with solids dispersed in it is poured through the filter paper and down the narrow tube of the funnels. Meanwhile, the solids remain on the filter paper and can be separated from the liquid.

Principle of Funnels

The principle of funnels depends on the type of funnel. Typical funnel principles are as follows:

1. Separation of Solid and Liquid Using a Glass Funnels

To separate solids and liquids using a glass funnel, filter paper is first placed in an inverted triangular funnel made of glass. By pouring a suspension of solids through the opening of the funnel, the insoluble material is obtained as a residue on the filter paper, while the liquid passes through the filter paper and is separated as a filtrate.

Solid-liquid separation with glass funnels is the simplest example of funnels used for separating solids and liquids, and many of you have used it in elementary school science experiments.

2. Separation of Two Liquids Using Separating Funnels

To separate two liquids using separating funnels, first pour a mixture of two unmixed liquids into the eggplant-shaped container of the separating funnels and allow it to stand still. The upper layer contains a solution of low specific gravity (e.g., oil) and the lower layer contains a solution of high specific gravity (e.g., water), which are clearly separated as two liquids.

The two liquids can be separated by opening the bottom cock and removing only the lower layer. 

3. Separation of Solids and Liquids Using Buchner Funnels

At the opening of the Buchner funnel, a circular filtration plate with numerous pores is installed. A filter paper is placed in the circular section, and a suspension of dispersed solids is poured through the opening of the Buchner funnel.

In many cases, the suspension to be poured is one that is difficult to separate from the solid and solution in a normal glass funnel due to its high viscosity or other reasons. For this reason, Buchner funnels are installed in a special device called a suction filtration bottle, and the separation operation is performed by pulling off the solvent by suction with an aspirator.

Filtration using an aspirator is called suction filtration or decompression filtration. Its advantage is that the filtration operation is completed in a shorter time compared to natural flow.

Types of Funnels

There are various types of separation funnels used in chemical experiments, depending on the application. Three types of funnels in particular are often used: glass funnels, separating funnels, and Buchner funnels.

1. Glass Funnels

Glass funnels are used to separate solid and liquid components in a suspension. Glass is the most common material for this type of funnels because of its resistance to organic solvents, which are often used in chemical experiments. A filter paper is laid over the inverted triangular opening.

2. Liquid Separating Funnels

Separating funnels are used to separate two unmixed liquids.

A cock is attached to the glass tube to allow the liquid to flow down, and by opening the cock, the liquid can be passed through and taken out.

3. Buchner Funnels

The Buchner funnels are used to quickly filter suspensions containing large amounts of solids or suspensions with high viscosity. It is made of porcelain, which is resistant to organic solvents and is used by setting it in a suction filtration bottle. In synthetic organic chemistry experiments, Buchner funnels are often used to separate large amounts of crystals from the solvent in a short time.

Other Information on Funnels

Funnel Materials and Precautions for Use

Funnel materials vary widely, including plastic, stainless steel, and glass, and should be selected according to the chemical properties of the liquid to be dispensed.

For example, in many chemical experiments, organic solvents are used that are highly reactive with plastics, so glass funnels with excellent resistance to organic solvents are used.

What Is Filtration Equipment?

Filtration is the process of removing substances from a liquid and separating the solid and liquid mixture.

Particles suspended in a liquid are called a slurry, and a sheet of porous material used to separate the liquid and solids is called a filter media. A filtration equipment device is a device that performs filtration using filter media to separate liquids and solids in a liquid. The filter media, which is a porous plate with fine holes, is used to separate liquids and solids.

Filtration is one of the oldest technologies used by humans, and is said to have been used to filter wine in ancient Mesopotamia around 6000 BC.

Uses of Filtration Equipment

Filtration equipment is used in a variety of places. Examples include filtration for swimming pools, bath water, machine tools, and wastewater, sewage filtration, and filtration for air and water purifiers.

An example of a use for simple filtration is the use of a coffee dripper to filter coffee. Similar filters are also used to separate dust sucked up by vacuum cleaners, and filters in air conditioners and air purifiers filter particles in gases rather than liquids. In the production process for Japanese sake, the filtration process is also used to separate sake from sake lees.

There are also filtration equipment devices for drinking water purification, rainwater filtration equipment for securing drinking water for disaster victims, and filtration equipment for well water.

Principle Uses of Filtration Equipment

Filtration equipment uses filtration media to separate liquids and solids in liquids. There are three main types of filtration equipment: cake filtration equipment, cakeless filtration equipment, and clarification filtration equipment.

In filtration equipment, a cake layer grows on the filtration media as filtration progresses. When a predetermined amount of the cake layer is formed, the cake must be discharged.

In the cakeless filtration method, the liquid flows at high speed over the filter surface, and the cake layer is agitated and removed, enabling continuous use. Cakeless filtration is also called dynamic filtration due to its dynamic characteristics.

Clarification filtration equipment is used to further remove turbidity that could not be removed by other methods of purifying water. The water is passed through filter media such as sand to supplement and separate the turbid substances. Particles that are supplemented are much smaller than the space between the filter media, but they are supplemented by the cohesive action. Therefore, cohesionless particles cannot be supplemented by sand filtration.

What Is a Warehouse Management System (WMS)?

A warehouse management system (WMS) is a management system that specializes in all operations performed in a warehouse, such as receiving/issuing, inventory control, and stocktaking.

Similar to the warehouse management system (WMS), an inventory management system is a system that manages the inventory and quantity of products.

A warehouse management system (WMS) is a system that specializes in overall management in a warehouse, not only inventory management but also more detailed management of operations performed in the warehouse, such as receiving/issuing history, inventory, product location, and personnel management. In particular, warehouse operations can be standardized.

Warehouse operations, in particular, can be effectively managed by this system to standardize and streamline operations, prevent errors, and reduce costs.

Uses of Warehouse Management System (WMS)

Warehouse management systems (WMS) are used in all industries that require inventory management, including the logistics and manufacturing industries. In recent years, they are also being used by retailers and restaurants, regardless of the size of their business, and there is a growing demand for more efficient warehouse management operations and IoT.

Traditionally, a warehouse management system (WMS) has been conducted using paper or Excel-based systems. However, such systems required manual input for every entry and exit of goods, and a great deal of labor was required to manage inventory locations. In addition, as the workload and number of workers increase, the number of errors, such as incorrect data entry or forgetting to enter data, tends to increase.

By implementing a warehouse management system (WMS), it is possible to reflect information automatically on incoming and outgoing shipments, including their location in the warehouse. Combined use of portable terminals, such as barcode readers, eliminates the need for data entry work and prevents errors such as mistaken entries.

Principle of Warehouse Management System (WMS)

A warehouse management system (WMS) generally includes the following functions:

1. Receiving Management

Receiving schedule and label management of goods to be received. 

2. Inventory Control

Inventory control manages information, such as the number of items in stock, location, and date of manufacture. 

3. Shipping Control

Manage shipping schedules, provide instructions for goods to be shipped, and create picking lists.

4. Inventory Control

Inventory display function and input assistance using a scanner are available. Inventory is managed in real time, reducing the time and effort required for inventory.

5. Bookkeeping and Label Issuance

Delivery slips and labels can be issued.

These functions can be further enhanced by input assistance using portable terminals, such as barcode readers and scanners, and by using tablets and other devices to simplify input and confirmation operations. A warehouse management system (WMS) can be integrated with other management systems, but it is often used as a stand-alone system.

This is because a warehouse management system (WMS) requires flexibility in the field, and the system and management methods must be flexible.

How to Select a Warehouse Management System (WMS)

When choosing a warehouse management system (WMS), it is important to consider whether the system has the features you are looking for, whether it is easy to use, and whether it can be integrated with other systems.

Although each industry handles different items, the functions performed by a warehouse management system (WMS) basically do not vary depending on the items handled. Most warehouse management systems are equipped with the basic functions necessary to manage parts, products, materials, food, and other items. On the other hand, some warehouse management system (WMS) specialize in parts, so it is important to decide which management functions your company will focus on.

Another key factor in choosing a warehouse management system (WMS) is whether it is easy to use and easy to view for the employees handling the system. For warehouse operations in a large site, some types of systems can be carried around on tablets, while others can only be handled on PCs. It is important to make a selection based on actual operations.

Basically, a warehouse management system (WMS) is usually linked to other systems. The main examples are procurement management systems, financial management systems, and other systems that manage people, goods, money, and information. The ability to link with such systems is another important point, and it is necessary to select one that allows centralized management.

What Is a Process Control System?

A process control system is a system that streamlines the process control operations in the manufacturing industry.

It refers to a process control system that manages “processes,” which systematically categorize each operation at a manufacturing site, and keeps track of the progress. Processes are operations such as receiving, inspection, processing, and shipping in the manufacturing industry.

The purpose of a process control system is to ensure that products are delivered on time and that each process of manufacturing is planned and operated efficiently. The system is also indispensable for production control because it has functions such as inventory control, worker management, and quality control.

Uses of Process Control Systems

Process control systems are widely used in all areas of production. They are used not only in manufacturing but also, in some cases, in software development, in terms of managing the software development process.

In larger manufacturing sites, process control systems are generally operated as part of a higher-level production control system, rather than as a stand-alone system. In small factories or software development sites, it is used by setting up a process for each product and displaying it on a Gantt chart to grasp progress and manage delivery dates.

Some sites create and operate their own process control system using Excel, so small factories and software development sites operate with the minimum functions of a process control system.

Principle of Process Control Systems

The typical process of a control system works by following three steps: 

1. Process Setup

For each product, the sequence of processes is clarified, and the materials, parts, machinery, equipment, personnel, working hours, and deliverables for each process are set. Since this includes not only in-house production processes but also all processes outsourced to subcontractors, it is also necessary to identify whether the process is outsourced or in-house. 

2. Process Planning

Based on the quantity of products to be manufactured, the delivery date, and the working hours of each process, a schedule for each process is established and put into a Gantt chart. A Gantt chart is a diagram in which the contents of each process are described on the vertical axis in the order of processes and the schedule bar on the horizontal axis, so that the flow of the entire process can be visually confirmed.

The process plan clarifies the work to be performed in each process and also specifies the assignment of workers. If an inspection is required before the deliverables are transferred to the next process, the inspection is also considered as one of the processes, and the procedures and pass/fail criteria are specified. 

3. Process Progress Management

Record the status of work in the field and constantly check the progress. At this time, visualization of the plan and actual results, such as a Gantt chart, makes it easier to grasp the progress.

A process plan is not something that can be established only once. After the plan is executed, the actual results are evaluated, and if there are areas for improvement, they can be fed back into the next work plan, leading to further streamlining of the work process, which can also be used for on-site improvements.

Other Information on Process Control Systems

Functions of Process Control Systems

The basic functions of a process control system are schedule management and progress management. Other functions include inventory control, worker management, and quality control, and they are operated in various combinations depending on the product, manufacturing type, and scale of production.

Inventory Control System
Inventory control systems are used in production control systems to grasp and control the amount of product inventory in real time at the distribution site. Inventory control systems are also used for inventory counts to determine the cause of the difference between the actual number of items and the number of items in the data.

Worker Management System
A worker management system is a system that manages the entry and exit of workers and manages the assignment of workers. The system can view information on the working conditions and health status of assigned workers, which is useful for utilizing human resources that are important for production management.

Quality Control System
A quality control system is a system used by a company to improve the quality of its products and services. Each company has different goals for quality control, and quality control systems are used to achieve those goals.

What Is a Drive Chain?

A drive chain is a chain utilized to transmit power between rotating shafts that are spaced apart.

Most drive chains consist of metal roller chains. These roller chains operate in tandem with sprockets and thin gears to transfer power from the input to the output shaft.

Altering the sprocket teeth count on both the drive and driven ends can modify the rotation speed. Beyond drive chains, conveyor chains are also used in factories for product transportation along production lines.

Uses of Drive Chains

Drive chains find application in driving the wheels of bicycles and motorcycles, in automobile engines and transmissions, and industrial machinery. Bicycle drive chains represent a common example of their application in everyday life.

Drive chains in sports bicycles, like road and mountain bikes, must not only convey power but also adapt to various speed shifts. The chainring and the rear wheel sprockets, featuring different teeth counts, can be swapped to alter gear ratios.

The design of the drive chain allows significant lateral movement based on the sprocket’s position, enhancing its versatility. In automobiles, drive chains are integral to engine timing, transferring power in 4-wheel drives, linking transmissions to drive wheels in motorcycles, and operating in chainsaws and forklifts.

Principle of Drive Chains

The drive chain transmits power as the teeth of the driven sprocket engage the chain’s rollers, thus pulling the chain. Rollers, maintained in position by pins and bushings, with plates affixed on either side, facilitate continuous power transmission.

Structure of Drive Chains

The drive chain comprises four main components: pins, bushings, rollers, and plates.

1. Pin

Pins support rollers that directly receive power from sprockets and connect the plates. They must withstand significant shear stress during power transmission.

2. Bushing

Bushings facilitate the smooth sliding action between pins and rollers, essential when rollers engage with sprockets under pressure, thereby minimizing friction and wear.

3. Plate

Plates, connected by pins, transmit power under tension. Inner and outer plates are arranged alternately, and chains must be linked by connecting these plates.

4. Sealing Rings

Certain drive chains include sealing rings to encase lubricating grease for the bushings.

Other Information on Drive Chains

1. Standards for Drive Chain

Drive chains adhere to various domestic and international standards. Chain sizes are denoted in inches, with a three-digit number representing the pitch and inner pin width.

2. Alternatives to Drive Chain for Power Transmission

Aside from drive chains, rubber belts, gears, and shafts also transmit power. Nevertheless, drive chains are prevalent in daily-use products like cars and motorcycles due to their reliability and cost efficiency. Metal belts are commonly used in continuously variable transmissions (CVTs) for vehicles, though metal chains are sometimes preferred for their torque transmission efficiency despite being noisier, limiting their market presence.

What Is a Current Collector?

A current collector is a device used to supply electricity from an electric wire to a train or other transport device while it is running.

It is used as a power feeder for cranes, hoists, etc. in factories. Trolley wires are placed on the ceiling or sides of the track of the transport equipment, and current collector wheels and shoes are connected to the trolley to collect the power.

There are various types of current collectors, including pantographs commonly used on trains, pole collectors for cranes and hoists, and trolley poles.

Uses of Current Collectors

Current collectors are primarily used in self-propelled industrial and commercial equipment. Specific uses include the following:

• Overhead cranes and hoist cranes in factories
• Bullet trains and linear motor cars
• Trams and subway trains
• Self-propelled transport robots in factories

They are mainly used to move heavy machinery and equipment on a constant track. Current collectors require wires to be stretched, so they can only be used on predetermined tracks.

Principle of Current Collectors

Current collectors consist of the following parts: current collectors, arm, and insulator.

1. Electron Collector Part

The current collectors are the part that actually contacts the bare wire. It contacts the current-carrying point and conducts electricity. For this reason, alloys such as copper, tin, and carbon, which conduct electricity easily, are used. Since it is worn by contact, it needs to be replaced periodically. 

2. Arm Bar

The arm bar is the part that supports the electron collector while pressing it against the bare wire. A spring is used to press the current collectors against the wire. It is characterized by the fact that it has some play to cope with the impact of running. 

3. Insulator

The insulator prevents this voltage from being applied to the traveling equipment. If voltage is applied to the running gear, it is very dangerous because it can cause equipment failure or electrical shock. Insulation by insulators prevents such accidents.

Types of Current Collectors

There are various types of current collectors, of which pantographs, pole collectors, and trolley poles are three typical examples.

1. Pantograph

Pantographs are applied to various types of rolling stock and are the most common type of current collectors. There are two main types: the wheel type and the shoe type.

The wheel type collects power when the wheel contacts the overhead wires and has high arc resistance. On the other hand, the shoe type has a plate-shaped shoe in contact and provides a stable supply.

2. Pole Collector

The wheel of the pole collector makes contact with the bare trolley wire and collects power.

3. Trolley Pole

These current collectors were often used in trolleybuses and railroads in the past. It is made of iron or other metal pipe and energizes when the trolley wheel at the end comes into contact with an overhead line. Although the structure is simple, the number of trolley wheels is on the decline because of their tendency to separate from the overhead wires. It is applied to cranes in factories.

Other Information on Current Collectors

1. Reasons for Using Current Collectors

Trains run by rotating motors that use electric energy. There are many vehicles in the world, but it is surprisingly unknown that trains are the only vehicles that do not carry their own energy.

The reason for this is the performance and distance that trains can travel. If you want to run a heavy vehicle for a long time and over a long distance on electricity, batteries do not have enough energy capacity. A generator would be excessive, and energy for power generation would have to be provided separately. Therefore, if the vehicle is to be operated over a long distance, it must be replenished along the way.

Due to the above limitations, it was determined that the most efficient way to get electricity is to take it from an overhead line that has been electrified. Based on this idea, current collectors were invented as devices to collect electricity from overhead wires.

2. Changes in Current Collectors

Current collectors have been used in electric trains since their commercialization, including Japan’s first commercial train, which opened in 1895. The current collector at that time was a trolley pole with a single pole, which was replaced by a trolley pole with two poles when the two-wire overhead system was introduced.

However, the trolley pole must be manually operated by the conductor at junctions to prevent derailment. The pole must also be raised or lowered when changing the direction of travel. Therefore, as technology advanced, trolley poles gradually fell into disuse. As time progressed, view gels and pantographs were introduced to solve and improve various problems related to overhead wires and operation. Today, pantographs are widely used, and in Japan, pantographs are used almost exclusively.

When pantographs were first introduced, only foreign pantographs were available, but after much trial and error by domestic manufacturers, domestic pantographs became the mainstream. Even now, improvements are being made to improve the functions and performance of pantographs.