Locating bearing

A locating bearing support establishes a shaft's axial position relative to its housing while supplying the required mechanical support. Depending on the arrangement, a locating support can consist of one bearing or a coordinated set. Its function must be distinguished from a non-locating bearing support that accommodates axial displacement, including relative thermal expansion.^[ref]

For an ideal two-support example, place the locating support A at $z=0$ and a radially supporting, axially free support B at $z=200\mathrm{mm}$. An upward transverse gear load300N at $z=80\mathrm{mm}$ gives downward radial reactions180N at A and120N at B by static equilibrium. If the gear also exerts an axial force of120N and A is the sole axial restraint, the axial reaction at A is $-120\mathrm{N}$ and that at B is zero.

The magnitude of A's combined external reaction vector is $\sqrt{180^2+120^2}\approx 216.3\mathrm{N}$. This vector magnitude is a force-balance result, not automatically the catalogue's equivalent dynamic bearing load or life-rating input. Those calculations distinguish radial and axial loading according to bearing type and operating conditions. Helical gears provide a practical example requiring both load components.^[ref]

The location of the axial restraint also determines how shaft expansion changes component positions. If A fixes one end and the other support permits extension, a point a distance $z$ from A moves approximately $\alpha z\Delta T$ in a simple uniformly heated bar model. Thus choosing a locating support affects alignment and axial positioning as well as which support carries thrust.