Train Drive System
Suspension drive system
|Suspension drive system
There are only a few examples of the suspension drive system in use today, such as the Enoshima Electric Railway and the Hakone Tozan Railway. This method has the advantages of a very simple structure, low manufacturing cost, and the ability to accommodate large main motors.
The main electric motor is bridged between the wheel axle and the bogie frame (suspended between the wheel axle and the bogie frame), so it is called the suspension drive system.
In the suspension drive system, the main electric motor is arranged parallel to the axle, and the small gear (spur gear) on the main electric motor shaft drives the large gear on the axle.
|Suspension drive bogie (TDK583 type by Toyo Denki)|
|A bearing is provided on the axle side of the main electric motor, and this bearing part is placed on the wheel axle. Between the axle and the bearing, the bearing is sandwiched by a flat bearing called an axle metal. The main electric motor moves only on the circumference by the flat bearings, so the relative distance between the main electric motor and the wheel axle is constant. There are two types of support systems for this mounting part: the nose suspension system and the bar suspension system.
In the nose suspension method, a projection (nose) on one end of the main electric motor is fixed to the bogie frame.
A spring or anti-vibration rubber is inserted between the bogie frame and the nose to cope with axle mutation.
The bar suspension system is a system in which a bar-shaped part (bar) is attached to one end of the main electric motor and fixed to the bogie frame. This method is advantageous for bogies with a short axle distance, and a spring is inserted between the frame of the bogie and the bar. It was mainly used for streetcars and light railways.
The photo above left is Deha600 type (transferred from Tokyu Tamagawa line to Enoshima Electric Railway).
Cardan drive system
|The Cardan drive system is a system in which the main electric motor (motor) is fixed to the bogie frame on the spring and the gear system on the axle side is driven via a universal joint (universal joint).
The Cardan-driven trains with advanced design and performance that appeared in the 1950s were called “high-performance trains”. It contributed to increase the train operation density with high acceleration and deceleration performance. Typical example is JR 103 series train.
|Right Angle Cardan Drive System
The right-angle Cardan drive system is a combination of worm gear and spur gear, and the main electric motor is mounted on the bogie so that the drive shaft is parallel to the rail direction.
The use of spiral bevel gears made it possible to achieve a quietness that could not be achieved with parallel cardan drive, but it required high-precision machining, which made it difficult to put into practical use.
In Japan, Toshiba Corporation and Hitachi, Ltd. manufactured the TD parallel cardan drive system, which is mainly used by Sagami Railway and has been adopted in the current trains of Series 7000, 8000, and 9000.
The photo left is Sagami Railway Series 7000(7707F).
|Right Angle Cardan Driven Vehicles|
|TD Parallel Cardan Drive System
The TD parallel cardan drive system is a combination of two hollow-shaft parallel cardan flexure plate joints and a compact TD (Twin Disc) joint between the electric motor and the gear on the solid shaft.
If this TD coupling is replaced with a WN coupling, the structure is the same as the WN parallel cardan drive system.
Toyo Denki Mfg.
This system has been adopted by many JR and private railway companies because of its simpler structure, lower noise level, and high maintainability compared to the WN system.
The photo on the left shows the DT61G electric bogie of Series E231 of JR East.
|TD Parallel Cardan Driven Bogie|
|WN Parallel Cardan Drive System
In the WN parallel Cardan drive system, the main electric motor is fixed to the bogie frame parallel to the axle, and the output shaft of the main electric motor and the drive gear are connected via a WN coupling that permits large displacement.
Inside the WN coupling, displacement is absorbed by utilizing the tolerance between the cylindrical internal gear and the external gear installed inside it, and the internal external gear is fixed by a spring to prevent it from being misaligned. The WN coupling is a different mechanism from the Cardan coupling because it is an axle-less drive system with elastic support of the main electric motor load “on the spring”.
The photo on the left is Odakyu Electric Railway Type 5000 (5256F).
|WN Parallel Cardan Driven Vehicles|
|The name “WN” is said to be derived from the initials of Westinghouse Electric Company (an electrical manufacturer) and Natal Corporation (a gear manufacturer) in the U.S., which were involved in the development of the system. Odakyu Electric Railway’s current commuter trains use the WN parallel cardan system.|
main electric motor
DC double-winding commutator motor
|The DC double-winding commutator motor is a generation-old motor.|
|DC double-winding commutator motors are controlled by resistive control or field chopper control.
Regenerative braking can be used, but the structure is complicated and the weight tends to increase. There is also an AC commutator motor with the same structure that can be used for both AC and DC.
The output characteristic of the DC double-winding commutator motor is that it generates the maximum torque at startup, and as the rotation speed rises, the torque decreases and the rotational force increases, making it suitable for a wide range of speeds.
However, the problem was that the brushes and commutators were subject to wear and tear, which required consumable parts and maintenance.
Please click here for more information about DC motor brush material (carbon black).
|TM83 type DC double-winding commutator motor|
Cage Type Three-Phase AC Induction Motor
|The cage-type three-phase AC induction motor is currently the mainstream electric motor for electric trains.|
|This is an electric motor that generates a rotating magnetic field with three-phase alternating current and uses a cage rotor with a “cage structure” in which both ends of the conductors are shorted together. (Photo 3)
It generates AC voltage of voltage and frequency proportional to the instantaneous rotation speed, and is called the inverter method as speed control with excellent characteristics.
The advantage of this electric motor is easy maintenance as there are no brushes, slip rings or other wear or contact energized parts.
The above photos (2) and (3) show the MT68 cage-type three-phase AC induction motor installed in the JR East E231 Series.
Permanent Magnet Synchronous Motor
|Permanent magnet synchronous motors are considered to be the next generation of electric motors.|
|The feature of the permanent magnet synchronous motor is that the rotation speed is determined by the power supply frequency, and the running can be controlled as desired by the dedicated variable voltage variable frequency control VVVF inverter device. The smooth power is realized by the good start-up that is not found in conventional motors.
Also, there are no commutators, brushes, field excitation circuits, or slip rings (a mechanism that transmits power and signals without contact), so maintenance is easy.
|FS779M type bogie||DDM Permanent Magnet Synchronous Motor|
|The photo above left is an electric bogie of Tokyo Metro Series 16000 with permanent magnet synchronous motor, and the photo right is JR East Series E331 with DDM (direct drive motor ). Permanent magnet synchronous motors were adopted for the first time in Japan in 2006 by JR East with Series E331, and Tokyo Subway adopted them in the renewal of Series 02 (Marunouchi Line) that started in 2009, and started commercial operation in February 2010.
The Series 16000, introduced in November 2010, was the first mass-produced new train to adopt the system.
Bolsterless bogies and air springs
|TRS-03M type bogie (Tobu Railway)||FS072 type bogie (Seibu Railway)||TR246N type bogie (JR East)|
|The main type of bogies used today are bolster-less bog ies, such as the DT50 type bogies used in the JR East 205 Series.
Wing springs with stacked plate springs were used in the past, but the method of mounting the main electric motor has changed from the suspension drive system to the Cardan drive system, and bolster-less bogies were introduced to improve straight-line stability and reduce unsprung weight.
This bogie is said to have greatly surpassed the conventional type bogie with its simple structure and running performance that omits the pillow beam (bolster).
The JR East E233 Series, which is currently the mainstay of the line, is equipped with TR255 and DT71 type axle-beam bolsterless bogies, while the Odakyu Electric Railway 4000 Series is equipped with TS-1033 and TS-1034 type axle-beam box-supported bolsterless bogies.
|Air springs lined up in the inspection area||Air spring attached to the bogie||Air spring joint part male||Pneumatic spring joint part female|
|The air spring that connects the bogie to the car body is the suspension used in the pillow spring section of the bogie and greatly affects the ride quality.
It is equipped with an automatic height adjustment valve to maintain a constant car height, and the supply and exhaust air is adjusted by compressed air produced by an air compressor.
Air springs are widely used in everything from streetcars to bullet trains.
Current collector ( pantograph)
|In Tokyo, a voltage of 1,500V DC is flowing on the overhead wires. The positive electrode is on the overhead line side and the negative electrode is on the rail side. The overhead line is officially called an overhead train line, and is a wire that is stretched above the space where the train passes (around 4.5m above the ground) in the overhead train line system, and continuously supplies power while coming into contact with the power collector of the electric locomotive or train.
The power collectors are roughly classified into diamond-shaped and single-arm pantographs, and are manufactured by Toyo Denki Seisakusho and Koshin Seikosho. For the Tokyo Metro Ginza Line and Marunouchi Line, which use a third-gauge current collection system that is not an overhead wire system, please refer here.
Shinkansen, Joban Line (north of Toride Station) and Tsukuba Express (north of Moriya Station) use AC power.
|DC 1,500V overhead train line|
This was the main current-collecting system before the 1990s and is characterized by its good tracking performance at low and medium speeds.
It is called a rhombic pant ograph because it looks like a rhombus when viewed from the side as it rises. The frame of the pantograph is made of steel pipes and assembled into a truss shape from the upper and lower frames, and is composed of the slider and the part that comes in contact with the overhead wires.
The single arm type was produced in Japan until around 2005.
The single-arm pantograph was developed and patented by Faiveley S.A. of France in 1955. In Japan, it has been produced since the early 1990’s when the patent protection period of Faiveley S.A. ended, and electric railway companies began to equip the pantographs.
Compared with the rhombic pantograph, the area occupied by the pantograph when folded is smaller, and by reducing the joints that become sliding resistance and equipping stabilizers, it was possible to achieve both weight reduction and high rigidity of the frame, which improved the tracking performance of the overhead wires at high speed. Nowadays, single-arm pantographs have become the mainstream, as they have fewer components and are more cost-effective to manufacture and maintain.
|PS33D type pantograph|
Pneumatic Compressors, Electric Generators, Stationary Inverters
|HS20 type K Pneumatic Compressor||MH3119 Pneumatic Compressor||tank (of liquid)||Pneumatic pressurizer fitted|
Compressed air produced by a pneumatic press is stored in a tank and used to open and close doors and operate brake shoes when necessary.
When the air pressure in the tank drops below a predetermined level, the pneumatic comp ressor is triggered. The pneumatic compressor is an important device of the train which cannot run if it does not work. In recent years, the pneumatic compressor has been designed to be quiet when in operation.
Photo (3) shows the Odakyu 4000 type and Photo (4) shows the Odakyu 8000 type.
An electric generator, commonly called an MG ( Motor Generator), is a generator that produces service power for in-train fluorescent lights, air-conditioning and heating units, control units, etc. The generator is input from DC high-voltage power from an overhead line and generates AC low-voltage power (AC100V or higher) to be used as service power. The MG is input from DC high-voltage power from overhead lines, and the generator generates AC low-voltage power (AC100V or higher) to be used as service power. This equipment was adopted during the period when power conversion with semiconductor devices was difficult (until the 1980s). Due in part to the poor power conversion efficiency, the power conversion method has now shifted to stationary inverter control and other power conversion methods.
|Stationary Inverter (SIV)
Unlike conventional electric generators, stationary inverters are mainly used as service power supplies that do not have a drive unit. It is also called static inverterorSIV(Static InVerter ) to distinguish it from the VVVF inverter control system for running trains. When it was first introduced, it was an inverter using GTO elements, but now it consists mainly of IGBTs(Insulated GateBipolar Transistors ). Since the SIVs are not able to operate if they stop, the trains are equipped with two or more SIVs in a train formation or a dual-mode inverter system in which the VVVF inverter for running trains is operated as a SIV in an emergency.
Close coupling and semi-permanent coupling
|Tobu Type 50050 Close Coupler||Connected state||JR East Series E233 Close Coupling||Connected and running|
The basic function of a close coupler is to transmit tension between cars. The couplers are equipped with the basic function of transmitting the tensile force between the cars.
When the couplers face each other, the square bar-shaped parts are inserted into each other’s holes and locked internally.
On cars equipped with the automatic uncoupling device, the release lever has an air cylinder built in, and the release can be operated with the train uncoupling switch in the driver’s cab. The box under the close coupling is a jumper coupler for control signals (Photo 3 above). This is a mechanism to connect the control circuit etc. by pushing in the rod which opens the cover of each other when coupling.
Semi-permanent couplers are used to connect intermediate cars in a fixed formation (see photo 3 and 4 above). The combination is made at the maintenance yard at the rail yard. This coupler is used on the assumption that it is not disengaged. In addition to this, brake pipes that supply air pressure for brakes and jumper plugs that connect electrical wiring, etc. are used to connect the cars.
|Tobu Type 6050 Permanent Coupler||Tobu Type 50050 Permanent Coupler|
|Parallel type automatic coupler
The parallel type automatic coupler is widely used for locomotives, general passenger cars, freight cars, etc., and has been used for many years on Japanese railroads. The coupling can be swiveled on a horizontal plane, and the vertical error (22mm gap) covers the coupling surface, allowing cars with couplings of different heights to be coupled together. In principle, this type of coupler is used only for emergency rescue purposes, and the Tsukuba Express, Keio Inokashira Line, and Tokyo Metro Nanboku Line (see the photo on the left) use this type of coupler for fixed formations only. The Tokyu Meguro Line and the Toei Subway Mita Line, which are directly connected to the Tsukuba Line, also use the same type of train.
|Parallel type automatic coupler|
Jumper plugs are connectors for connecting control circuits and power supplies between vehicles.
A thick cable about 1m long called a jumper plug has a female connector and a male jumper plug (left photo) on the car body side. While a coupler connects two cars mechanically, a jumper plug connects control and power supply between cars.
The photo shows the jumper plugs on the intermediate cars of Tokyo Subway Series 6000.