Self-contained modular pivot, notably for robots

A self-contained modular pivot mechanism for coupling first and second machine elements adapted to be rotated through any angle in relation to each other about an axis of rotation, comprising first and second portions connected to said first and second machine elements respectively, said first portion comprising a first tubular member, an internally toothed annulus of a reduction gear, means for rigidly connecting said first tubular member with said annulus, means for centering and locking said annulus against axial movement on a first flange, said first flange secured to the first machine element, said second portion comprising a second tubular member, a pair of rolling-contact bearings, means for disposing said pair of rolling-contact bearings between said first and second tubular members at their opposite ends to center and dispose coaxially said second tubular member in relation to said first tubular member, said second portion further comprising a second flange, means for detachably securing said second flange to said second tubular member at the portion thereof opposite to said first flange, a pivot driving motor, means for securing said pivot driving motor to said second flange, and wherein said second machine element is secured to said second portion of said pivot mechanism, whereby access can be had to said motor independently of the connection between the two machine elements.