A precision measurement tool or specified dimension used to verify the correct spacing between opposing elevator guide rails during installation and maintenance.
Full Definition
Rail gauge refers both to the physical gauge tool — a calibrated steel bar or digital measuring instrument — used to measure the distance between the running faces of opposing guide rails, and to the specified nominal dimension itself. Correct rail gauge ensures that guide shoes or rollers run centrally and with the correct clearance, preventing excessive lateral forces, vibration, and guide shoe wear. Rail gauge is measured at each bracket location during installation and recorded in the installation record. It must be within the tolerances specified by the elevator manufacturer, typically ±0.5 mm. Gauge deviations indicate rail bracket distortion, building settlement, or thermal movement and must be corrected before the elevator is returned to service. In seismic design, wider rail gauge tolerances may be permitted with heavier guide shoes.
