the groove centre-lines in each coupling part lying on a sphere

Yielding couplings, i.e. with means permitting movement between the connected parts during the drive > Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts > one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members > the rolling members being balls, rollers, or the like, guided in grooves or sockets in both coupling parts > the rolling members being guided in grooves in both coupling parts > the groove centre-lines of each coupling part lying on a sphere

Yielding couplings, i.e. with means permitting movement between the connected parts during the drive (couplings disconnectable simply by axial movement F16D1/10; slip couplings F16D7/00) > Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts > one coupling part entering a sleeve of the other coupling part and connected thereto by sliding or rolling members (F16D3/18, F16D3/24 take precedence) > the rolling members being balls, rollers, or the like, guided in grooves or sockets in both coupling parts > the rolling members being guided in grooves in both coupling parts > the groove centre-lines in each coupling part lying on a sphere