Introduction / Context
Railway axle boxes house the bearings supporting wheelset axles. These bearings must sustain very high radial loads, shock, contamination, and long maintenance intervals. Selecting the correct rolling-element bearing type is essential for safety and durability.
Given Data / Assumptions
- Conventional freight/passenger railway service.
- Dominant radial loading; axial loads are minor and controlled by separate locating features where needed.
- Preference for standardized, field-proven bearing types.
Concept / Approach
Cylindrical roller bearings provide line contact with large radial load capacity and good speed capability. They are widely used in axle journal applications worldwide. Depending on locating/non-locating arrangements, one bearing may carry axial positioning (via shoulders/seating) while the other allows axial expansion.
Step-by-Step Solution
1) Identify load profile: high radial, low axial → favors roller over ball bearings.2) Compare roller types: cylindrical rollers excel in radial capacity and can be configured as locating/non-locating; spherical rollers add self-alignment but at higher cost and are less common in standard axle boxes.3) Conclude cylindrical roller bearings meet typical axle journal requirements.
Verification / Alternative check
Industry practice (AAR, UIC) and OEM catalogs list cylindrical roller bearings for axle journals, often in standardized cartridge or adapter assemblies.
Why Other Options Are Wrong
- Deep groove ball bearing: limited radial capacity relative to rollers for the same envelope.
- Double row self-aligning ball bearing: better misalignment tolerance but lower radial capacity than cylindrical rollers.
- Double row spherical roller bearing: high capacity and self-alignment, but typically used where misalignment is severe; not the mainstream choice for standard axle boxes.
- Tapered roller bearing: carries combined loads and is used in some rail applications, but the standard textbook MCQ answer for axle boxes is the cylindrical roller bearing.
Common Pitfalls
- Assuming self-aligning designs are necessary; axle journal housings are engineered to maintain alignment within bearing limits.
Final Answer
cylindrical roller bearing
Discussion & Comments