Q1: What is the pivot friction apparatus used for in engineering education?
The FX-522 is used to investigate friction in axial (pivot) bearings — bearings that support loads acting along the shaft axis. Students measure the friction torque at the onset of rotation for different bearing cone angles, bearing housing materials, and axial load magnitudes, developing a quantitative understanding of how these three variables independently affect axial bearing friction. A rolling contact bearing comparison experiment is also supported.
Q2: What is the effect of cone angle on pivot bearing friction?
The cone angle determines the geometry of the contact surface between the bearing journal and the housing. As the cone angle decreases from 180° (flat disc) toward a sharper point, the contact radius and contact pressure distribution change, altering the friction torque for the same axial load and material pairing. The FX-523 allows students to measure this effect directly by testing all four cone angles — 60°, 90°, 120°, and 180° — under the same axial load and material conditions.
Q3: How is the friction torque measured on the FX-522?
Friction torque is measured using the onset-of-motion method. A rope is wound around the 200 mm disc periphery and loaded incrementally using weights on a hanger, or pulled by hand. The load at which the shaft just begins to rotate at near-constant slow speed corresponds to the friction torque of the bearing at the current axial load, cone angle, and material combination. The friction torque equals the applied rope load multiplied by the disc radius (100 mm).
Q4: How is the axial load varied on the FX-522?
The axial load is varied by stacking calibrated weights on the upper surface of the aluminium disc. The disc’s own weight contributes a baseline axial load, and the two additional 5 kg weights — along with the fine-increment weight set — allow the total axial load to be increased in controlled steps. Repeating the friction torque measurement at each axial load level generates a friction torque versus axial load characteristic for each bearing configuration.
Q5: What is included in the scope of delivery for the FX-522?
The FX-522 is supplied as a complete experimental kit including: one pivot friction experimental unit with vertical shaft, anodised aluminium disc, interchangeable bearing journals (60°, 90°, 120°, 180°), and interchangeable bearing housings; two sets of calibrated weights (2 x 0.5 N, 2 x 5 N hangers, 4 x 2 N, 4 x 1 N, 6 x 0.5 N, 10 x 0.1 N); two additional 5 kg axial loading weights; one thread; one storage unit with foam inlay; and one instructional manual covering experimental procedures, cone angle theory, and data recording guidance.
