Summary

Wheels carry the vehicle’s load and touch the rail directly. For this reason, they are among the most safety-critical parts of any train. A solid rolled wheel is a single-piece steel wheel. Manufacturers form it by forging and rolling. Both passenger and freight vehicles use this type of wheel widely. This article explains the structure of solid rolled wheels and the quality principles behind them. It then presents a freight wagon wheel supply project by WCE’s Rail Technology and Engineering Business Unit (RTE).

1. What Is a Solid Rolled Wheel?

Engineers also call a solid rolled wheel a monobloc wheel. Its hub, plate and rim come from one piece of steel, with no separate tyre. The American Public Transportation Association (APTA) defines “wrought” as a forging process that rolls metal into a disc-shaped part [2].

In Europe, EN 13262 sets the characteristics of solid forged and rolled wheels for all track gauges. It defines five steel grades: ER6, ER7, ER8, ERS8 and ER9. In addition, it covers wheels made from vacuum-degassed steel [1].

2. Wheel Anatomy

APTA defines the main parts of a wheel as follows [2]:

• Hub – the central cylinder that fits onto the axle
• Plate – the thinner section that links the hub to the rim
• Rim – the ring at the wheel’s outer edge
• Tread – the outer surface of the rim that runs on the rail
• Flange – the lip that sticks out from the tread and guides the wheel along the rail

3. Quality Principles

3.1 Heat Treatment and Surface Finishing

ASTM A504 requires rim quenching and shot peening for wrought carbon steel wheels. After that, the manufacturer finishes each wheel by rough boring and machining [3]. Rim quenching hardens the tread so it resists wear. Meanwhile, the rest of the wheel stays tough.

3.2 Inspection and Testing

The same standard also calls for several checks [3]. First, a heat analysis confirms the chemical composition. Next, a Brinell test measures rim hardness. Finally, ultrasonic and magnetic particle methods check the wheel without damaging it. In addition, APTA requires the supplier to give the purchaser the results of all required tests [2].

3.3 Marking for Traceability

Every wheel must carry identification marks. APTA prefers these marks on the front or back hub face whenever practical [2]. As a result, operators can trace each wheel back to its production lot and test results throughout its service life.

4. Case Study: Solid Rolled Freight Wagon Wheels by WCE RTE

• Scope: Supply and delivery of 600 solid rolled wheels, 300 each for two freight wagon types
• Delivery point: The client’s stores warehouse
• Client: A client in the rail sector
• Contract period: Approximately 3 months
• Progress: All wheels delivered – 100% completed as planned

The cover image shows the delivery process. On the left, a forklift unloads wrapped wheels from a shipping container. On the right, wrapped wheel stacks stand in neat rows, ready for handover. AI created all images as technical illustrations. They are not site photographs, and they do not identify any person, client or location.

5. Observations from This Project

• Large orders of safety-critical parts need careful planning. Production, transport and receiving must work together so the full quantity arrives on time.
• The wheels travelled in protective covers inside shipping containers. This helps protect the tread and flange from damage during transport and storage.
• Separating the two wheel types from the transport stage onward makes receiving and warehousing faster and more accurate.

6. WCE Services

WCE’s Rail Technology and Engineering Business Unit (RTE) provides engineering, maintenance and component supply for railway rolling stock. We serve both passenger and freight fleets, from sourcing and transport through to delivery.

Contact: +66 65-937-6283 | international@wce.co.th | www.wce.co.th
We engineer your success.

References

[1] CEN. EN 13262:2020 Railway applications – Wheelsets and bogies – Wheels – Product requirements. https://www.sis.se/en/produkter/railway-engineering/railway-rolling-stock/general/ss-en-132622020/ (accessed 8 Oct 2026)
[2] American Public Transportation Association (APTA). APTA PR-M-S-012-99, Rev. 3: Manufacture of Wrought Steel Wheels. 2025. https://apta.com/wp-content/uploads/APTA-PR-M-S-012-99_R3.pdf (accessed 8 Oct 2026)
[3] ASTM International. ASTM A504/A504M-08(2013) Standard Specification for Wrought Carbon Steel Wheels. https://store.astm.org/a0504_a0504m-08r13.html (accessed 8 Oct 2026)