We manufacture and sell railway wheels, axles, and bogie trucks, as well as forged products including crankshafts, an important component in automobile engines. Our products meet needs for extremely high dependability and safety.


Railway Parts


Excellent microcleanliness

Undesirable inclusions or voids in wheel material may cause subsurface cracking under severe wheel loads. Therefore, ultrasonic testing criteria have been revised to be stricter in North America to prevent defects in freight car wheels.
Nippon Steel & Sumitomo Metal wheels are able to confidently satisfy these new criteria, owing to the world's highest level of cleanliness achieved by excellent steelmaking technologies.

Estimation of permissible defect size according to fracture mechanics

Estimation of permissible defect size according to fracture mechanics
Tread dia. : φ914mm (36") Static wheel load : 160kN (36,000lbs)
US Patent No. US 6,357,297 & US 6,372,057

Technological development

We are constantly engaged in research and development to contribute to the rail industry with new products that meet the demands of the day. A typical example is the "New Corrugated (HT Corrugated) Wheel," which allows for lightweight design by combining the concept that a "corrugated plate can be thinner than a flat plate because it is stiffer than a flat plate" with the "HT (High Toughness) wheel," which has excellent resistance to the effects of heating due to tread braking.

High Toughness (HT) Wheel

We developed the world-leading High Toughness (HT) wheel as a wheel that is not susceptible to changes in residual stress despite the thermal effects of tread braking.

Comparison of residual stress after drag braking

Residual stress distribution after drag braking
V=80km/h(50mph), μP=300kgf(660lbs.), 1hour duration

New (HT) corrugated wheel

The New (HT) Corrugated Wheel has been developed based on the same concept as the High Toughness Wheel.
It combines the features of being lightweight and braking heat-resistant.


Solid wheel
Solid Wheel
Corrugated wheel
Corrugated Wheel
A type
A type
A type solid wheel
A type Wheel
A type corrugated wheel
A type Corrugated Wheel
A type braking heat-resistant (HT) wheel
A type High Toughness Wheel
A type braking heat-resistant new corrugated wheel
A type High Toughness Corrugated Wheel
B type
B type
B type solid wheel
B type Wheel
B type corrugated wheel
B type Corrugated Wheel
C type
C type
C type wheel
C type Wheel
Noise damping wheel
Noise damping effect


Optimal design

Based on our years of experience and performance, we offer total design of parts and components, including gears, gear cases and bearings, suited to each user's applications. In particular, in recent years, as new types of trains such as the Shinkansen are being built to run at higher speeds, we have continued to strive to incorporate improved weight, quietness, and safety performance into our development and design work in order to meet clients' expectations.

Superior testing facilities

Final inspection rolling rig testers, as well as a variety of other types of test equipment, such as high-speed loaded spin test equipment exclusively for drive units, normal- and low-temperature starting testers; and a swaying coupling load tester, allow us to provide optimized assessment and evaluation results.

Sophisticated manufacturing technology and facilities and an integrated quality control system

We are also equipped with steelmaking facilities, forging and heat treatment facilities, as well as gear machining and honing facilities, to supply a variety of high-quality gears under an integrated quality control system. In addition, our gear cases are highly precision-machined, and then assembled and inspected in a fully equipped cleanroom under strict control systems.


Gear assemblies for traditional railway cars (mono-block gear case)

Gear assemblies for traditional railway cars (split gear case)

Gear assemblies for Shinkansen bullet train cars (Aluminum gear case)

Drive unit mechanism

Gear Coupling


Superb manufacturing technology and facilities

We operate extensive steelmaking facilities suited to the manufacture of a variety of products. Our facilities include those with forging, heat treatment, machining and testing capabilities, and they utilize sophisticated manufacturing technologies developed through years of experience. We can assure both consistent quality and a high level of dimensional accuracy.

High-quality forging stock

Our forging stock is manufactured using Numerical Control (NC), resulting in superior uniformity. Performing simultaneous forging in four directions at once makes it possible to manufacture products with consistently high levels of quality.

High dimensional accuracy

Equipped with a full range of automated, high-output machining equipment for lathing, grinding, and finishing the end faces of axles, we can achieve high dimensional accuracy by using the most suitable machining tools for each shape.

Integrated quality control system

Using high-quality ingots and billets supplied by our own steel works and electric furnaces, we carry out manufacturing under a stringent, integrated quality control system in all processes from raw material to final shipment.


Drive axle for electric train

Trailing axle for electric train

Trailing axle for freight cars

Hollow axle

Developed to reduce unsprung mass, the hollow axle achieves weight reduction of around 20% per unit.
The hollow structure also enables ultrasonic flaw detection from the inside, making inspection easy and accurate.

Induction-hardened axle

Induction-hardened axles are subjected to induction hardening on the axle surface, resulting in a great increase in fatigue strength.
They are widely used for high-speed, heavy-load rolling stock.


Currently, the main type of coupler is known as the Tight-Lock Coupler. It has no clearance between the contact parts to offer a smooth, comfortable ride even when the train is starting or braking. These are known as rotary-type couplers. They maintain their coupling with parts known as locks. This system is widely employed on the Shinkansen as well as other private and public railways.
In addition, we design and manufacture coupler systems that comply with specifications for higher speed trains and improved curving performance.

We have also developed a double-action-type rubber draft gear to enabling coupling longer and heavier trains and to reduce shock-noise on starting and braking. This mechanism is now widely employed in cars on private and public railways.



Rotary Key-Block Type Tight-Lock Automatic Coupler
Semi-Permanent Type Coupler
Tight-Lock Coupler for Shinkansen
Automatic Tight-Lock Coupler
Bar-Type Coupler

Rubber Draft Gear

W-Action Type
Noise level: 10 to 15 dB reduction


Superior manufacturing technology

No fasteners are used in the assembly of the wheelsets, which are mounted by a tight-fit technique utilizing only the tightening force between the fitted parts. We also have a hydraulic press fitting technology, which accomplishes smooth fitting, using hydraulic pressure and high-precision dimensional control of the fitted parts.

Superior facilities

We have wheel and bearing mounting presses for various types of products, as well as run-out and balance measuring equipment and roller rigs for post-assembly testing.


High-speed driving wheelset

High-speed trailing wheelset

Driving wheelset for commuter trains

Trailing wheelset for commuter trains


Bogies for the Shinkansen must be built for safe and comfortable rides at speeds exceeding 300 km per hour. The utmost care is given to safety, and each bogie undergoes all necessary tests. Currently, we are engaged in an effort to design new bogies for even faster speeds.

We make the fullest use of the wealth of experience and know-how we have gained in the many years we have worked to meet the needs of our customers, including both public and private enterprises operating all types of railways. These efforts include the manufacture and design of bogies for linear motor cars. These bogies must be small in size to accommodate cars built low to the ground. Our breakthrough success in meeting this requirement has enabled builders to reduce the section area of tunnels to a minimum and to achieve lower construction costs. We have also developed bogies for tramcars that must accommodate barrier-free design featuring very low car floors.


Bogies for Shinkansen bullet trains
Bogies without bolsters for electric trains
Bogies with bolsters for electric trains
Bogies for subway linear motor cars
Bogies for tramcars with lower floors
Bogies without bolsters for diesel-driven railway cars
Bogies with bolsters for diesel-driven railway cars


Features of forged steel brake disks

  1. 1. Superior resistance to cracks from heat
  2. 2. Significantly higher toughness to avoid fractures
  3. 3. Superior wear resistance


Disks attached at the wheel


Active suspension system

This system reduces the amount of swaying in railcars by over half compared with conventional cars. This is the first time this has been successfully brought to market, and our product has already been incorporated into first-class trains such as the Shinkansen and other express trains. In this system, actuators located between the car body and the bogies immediately compensate for any swaying movement sensed in the car body. We can also optimally tune the system for each car and rail line, providing passengers with the comfortable ride they need.

Pneumatic spring tilting system

This system can enhance train curving speeds by 10 to 15 km/h, which enables much earlier train arrival times. Air springs installed on the bogies are inflated and deflated to tilt the car body, in the same way that a motorcycle rider inclines his or her body when cornering, allowing the vehicle to take curves smoothly. This system gives the bogies a far more simple construction than pendulum-type car bodies, also resulting in easier maintenance.

Status monitoring system

This system has the function of providing data that can be used to help locate the source of any abnormal car vibration and to manage ride comfort. For instance, it constantly looks out for any occurrence of "hunting," which directly affects running safety, At the same time, it also capable of recording all data related to car vibration and ride comfort to assist in car inspection and maintenance. This can be accomplished by a simple mechanism consisting of accelerometers and signal processing equipment.


Active suspension system

Pneumatic spring tilting system


  • They are light and compact.
  • Their response time is short.
  • They have a small number of parts and are easy to maintain.


Caliper used for Shinkansen
Caliper used for monorail
Caliper used for new transport system

Variable load rotational bending fatigue tester for railcar axles


It is very important to accurately assess the actual strength of axles to make them both adequately safe and lightweight. Due to test equipment limitations, fatigue testing on actual axles has been conducted under fixed amplitude loads. However, the loads on actual cars constantly fluctuate, and it would be difficult to say that actual conditions have been recreated in those tests. Therefore, a new tester, capable of simulating variable load conditions closer to actual operation, was introduced in 1995 to replace the conventional fixed -load rotational bending fatigue tester.


Testing simulating actual conditions

We can verify the fatigue strength of axles, including the fitted parts, by assembling test wheels and a test axle that matches an actual axle.

Testing by automatic control

Tests can be conducted at maximum loads of up to 157kN, and programming the conditions allows for long-term unattended operation testing.

High-speed brake tester for railcars


With the increasing speed of trains, the need to investigate high-speed braking performance of brake disks for railway applications has increased. Therefore, we introduced a high-speed brake test machine in 2001 in addition to our conventional tread and disk brake test equipment. In addition to brake testing at the equivalent of up to 600km/h, this machine also handles basic brake performance tests and durability tests, as well as run-curve test conditions similar to those in an actual car, with controlled brake torque and deceleration rate.


Brake testing compatible with increased speeds

Brake testing is possible at maximum speeds of 600km/h (with a wheel diameter of 860mm), making it possible to perform high-speed compatible brake performance and durability testing. (16 ton-equivalent severe-load brake testing is also possible at 400km/h with a wheel diameter of 860mm)

Various brake control tests (run-curve)

Brake tests are also possible with constant torque control and constant deceleration rate control, making it possible to conduct brake tests under conditions similar to those in actual operation, taking grade, run-curve, running wind, etc. into consideration. Test data, such as average friction coefficient and torque can also be automatically recorded.

High-speed loaded spin test equipment exclusively for railcar drive units


High-speed compatible

We have achieved maximum test speeds of 500km/h (200km/h faster than our conventional test performance), making the testing equipment compatible with high-speed train development.

Evaluation under actual car torque loads

In the past, performance was verified by running tests on actual cars after the cars had been completed. With this testing equipment, characteristics can be simulated under actual torque load conditions.

Analysis and predictive design of acoustic characteristics

By employing a semi-anechoic chamber and an axel and pinion shaft drive system, we can now analyze the noise sources and acoustic characteristics from the drive unit itself, without any disturbance from other noise sources, facilitating more accurate predictive design.

Railcar bogie spin testing rig


High-speed railway systems such as the Shinkansen have drawn attention from the viewpoints of environmental and energy issues. At the same time, much higher speeds are being pursued. The bogie spin testing rig has rotating rail-wheels that correspond to rails, on which a load frame, which corresponds to an actual car body, is set. This allows the various problems that arise when a railcar is running at high speeds, such as running instability, to be worked out in advance.


High-speed compatible testing

Having attained a maximum test speed of 500km/h, we can conduct running-stability validation tests that are compatible with the future development of high-speed performance.

Testing for all types of bogies

The track gauge and axle center-distance are all variable on the test machine to enable testing of a variety of bogies.

Fatigue test equipment for railcar bogies


Railcar bogies must meet extremely high standards. It is also important that they are lightweight. Using the bogie fatigue tester, we can conduct strength assessment tests to check long-term serviceability by applying repetitive loads that simulate actual usage conditions of real bogies.


Testing under various load conditions

Testing can be conducted under various load conditions, such as several sine wave and rectangular wave load waveforms, and load waveforms that simulate actual conditions.

Testing by automatic control

Fatigue testing under long-term unattended operating conditions can be conducted by automatic control.

Automotive and construction machinery parts

Industrial machinery parts

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