Patent ID: 7024780

Claim:
A method of determining whether a guide rail has a rectilinearity suitable for use in an elevator installation for moving persons or goods, comprising the steps of: a. prior to use in an elevator installation, orienting an elevator guide rail with a longitudinal axis substantially parallel to a reference axis; b. emitting at least one light beam along the reference axis from a light source; c. providing a light detector for detecting the light beam; d. displacing at least one of the light source and the light detector along an elevator car travel face of the elevator guide rail and detecting a spacing between the guide rail travel face and the reference axis at a zero position on the elevator guide rail and at a plurality of spaced apart length positions on the elevator guide rail; e. determining whether there is a change in the detected spacing at any of the spaced apart length positions from the detected spacing at the zero position; and f. upon determining that there is at least one change in the detected spacings, calculating on the basis of a permissible deviation in rectilinearity whether each change in the spacings is permissible or impermissible whereby the elevator guide rail can be used in an elevator installation if all the changes are permissible.