What is a Wheelset
A wheelset consists of two wheels rigidly fixed on a single axle and rotating as a single unit. Passenger and freight wagons use solid-rolled wheels, while locomotives employ wheel centres with tyres. The wheelset serves as the main component for movement and keeping the rolling stock on the rails.
Structure and Components
- Wheels have a conical profile, allowing the wheelset to shift automatically when passing curves, thus preventing slippage.
- Flange — a projection on the inner part of the wheel that prevents derailment.
- Axle connects both wheels and transfers the load to the bearings.
- Bearings ensure free rotation of the axle within the axlebox and bogie.
- Locomotives are equipped with gearboxes for transmitting torque from the engine to the wheels.
The combination of these elements forms the wheelset.
Main Functions of the Wheelset
- Traction transmission from the traction motor to the rails.
- Load distribution of the rolling stock onto the rails, ensuring stability.
- Guiding function — keeping the wheelbase on the rails.
- Self-centering of the wheelset in the track gauge due to the conical wheel profile and flange.
Curve Negotiation
Since the wheels are rigidly fixed on the same axle, when negotiating a curve, the outer wheel must travel a longer distance. Due to the conical wheel profile, the axle shifts so that the outer wheel rests on a larger circumference than the inner one. This allows curves to be negotiated without wheel slip.
Wheelset Weight
Depending on the type of rolling stock, a wheelset may weigh between 1150 and 1450 kg.
Common Faults
- Cracks on wheels or axles — pose a serious safety hazard.
- Wheel tread wear — wear of the running surface of the wheel.
- Metal build-up — metal deposits occurring due to overheating and wear.
- Flat spot — flat areas on the running surface formed during wheel skidding.
- Flange thinning — reduction in flange thickness, impairing the wheel’s ability to stay in the gauge.
Maintenance and Standards
- Wheelsets are manufactured and serviced in accordance with technical regulations and standards.
- In case of wear, the wheel is re-profiled or the tyre is replaced.
- Regular inspections are carried out at depot technical inspection points and specialised service centres.
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