RACO trapezoidal thread spindles (TR) consist of a vortex or optionally ground spindle in combination with a spindle nut made of special bronze. Depending on the choice of spindle geometry and the drive, self-locking at standstill is achieved for this design. Even high static loads above the nominal dynamic load rating are safely held in any intermediate positions. Higher positioning speeds and lower friction are achieved by using multiple trapezoidal spindles.

At the same time, the surface quality prevents the "slip-stick effect", which describes the jerky sliding of solid bodies moving against each other. RACO also manufactures so-called hydrostatic spindles for this purpose.

Grinding in an air-conditioned room requires both compliance with tolerances for holding the workpieces in the machine and their dimensional accuracy in terms of concentricity and axial runout. The pitch distortion caused by heat input (whirling & hardening) is corrected and thus eliminated during grinding.