The overtravel unit protects the PHS1 probe head in the event of a collision by deflecting and providing an electrical signal which can be used by the CMM controller to stop machine motion.
A kinematic joint held in place by a coil spring enables the body to relocate itself once any obstruction has been removed.
NOTE: The head must be re-datumed in the event of overtravel.
Information on the re-datuming procedure is given in the PHS1 programmer's guide (Renishaw part number H-1000-6005).
The following figure shows the location and deflection capability of the overtravel unit:
Overtravel unit deflection: