Locating bearing
= 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>.<Rolling bearings by SKF>[Section B.2, printed p.70, arrangement functions and bearing supports consisting of one or more bearings]{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 $\sqrt{180^2+120^2}\approx216.3\,\mathrm N$. 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.<Shafts and Bearings by SDP-SI>[§4.0, cases(a)–(b), radial support reactions; case(g), helical-gear axial thrust and bearing loads]{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.