KD171 · Pivot Friction Apparatus

Experimental apparatus for the study of frictional torque and axial thrust in pivot bearings

Experiments

Verification of the frictional-torque vs. axial-thrust relation for a flat pivot: T = ⅔ μ W R
Influence of the cone angle (60°, 90°, 120°, 180°) on the frictional torque at constant thrust
Determination of the friction coefficient μ for a brass-on-steel contact pair
Comparison of a plain pivot with a ball thrust bearing — sliding vs. rolling friction
Application of measured μ values to the sizing of a conical clutch
Verification of Amontons' law across multiple pivot geometries

Description

Pivot bearings — the conical and flat end-supports that carry the axial load of a rotating shaft — are among the oldest machine elements in engineering, yet their tribological behaviour contains subtleties that are easy to overlook in a purely theoretical treatment. The frictional torque is not simply proportional to axial thrust: it depends critically on the geometry of the bearing surface. A shallow cone concentrates contact pressure into a small annular band and amplifies the friction torque dramatically compared with a flat pivot; a ball thrust bearing eliminates sliding contact almost entirely and reduces the torque by an order of magnitude.

Construction

A circular turntable is mounted on a vertical shaft and loaded axially by calibrated weights placed on its surface. The shaft tip engages one of four interchangeable pivot sets — cone angles of 60°, 90°, 120°, and 180° (flat) — seated in a fixed mild-steel housing. Pure torsion is applied to the turntable through a symmetric pair of cord-and-pulley load hangers, and the torque required to initiate rotation is read directly from the weight on the hangers. A ball thrust bearing is also supplied, enabling a direct comparison of rolling-element and plain-pivot performance under identical conditions.

KD171 interchangeable pivots — 60°, 90°, 120° and 180° (flat)

Specifications

Turntable Ø 200 mm, approx. 1 kg

Pivot sets 4 interchangeable — 60°, 90°, 120°, 180° (flat)

Pivot material brass (pivot) on mild steel (seat)

Thrust bearing ball thrust bearing included

Loading symmetric dual cord and pulley — applies pure torsion with no side loading

Measurable quantities axial thrust, frictional torque, friction coefficient μ

Mounting wall-mounted; bench support frame optional

Operation fully mechanical — no power, no software, no consumables

Scope of delivery

KD171 pivot-friction assembly
4 × pivot sets (60°, 90°, 120°, 180°)
2 × load hangers, 10 m spare cord
1 × ball thrust bearing set
Calibrated weights: 10×0.1 N, 10×0.2 N, 2×1 N, 8×2 N, 2×50 N, 1×100 N
Instruction manual

19 kg

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SCHIMB

15 ANI

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5 ANI

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