FM4-LO | Laser Optics

The FM4-LO contact wire measuring device is specially designed for static point measurement of contact wires. The laser beam of the FM4-LO determines the position of the catenary in relation to the track center as well as from the top of the rail.

This enables you to measure quickly and easily the:

  • Contact wire height and stagger (zig-zag)
  • Messenger wire height and stagger
  • Bridge and tunnel heights, height of crossing power lines
  • With accessories: Distance between pole leading edge and track center (FM4-LO Edge Configuration)


  • Project planning and construction of overhead line systems
  • Regulatory and maintenance tasks on catenary and contact lines
  • Calibration and control and of continuous, dynamic geometry measurement methods
  • Optimized for flexible and mobile use in light and long-distance rail


In combination with the measuring bar, the measuring device can measure contact wire stagger on track gauges in the range of 750 - 1676 mm. The measurements can be performed quickly and in any weather condition.


Designed for construction site environments

  • Target optics with crosshairs for quickly catenary detection in daylight and including bright sunshine
  • Non-contact laser distance measurement of catenary height, visible red laser spot on the target surface
  • Single or continuous measurements as useful search function and for differentiation of the distances
  • Automatic display illumination, LED back lit for target optic, stagger scale illumination
  • Special protection against dust and water for use at almost any weather conditions
  • Minimal staffing expenses for logistics and measurements
  • Without affecting traction power supply through contactless measurements and insulated track contact
  • Contactless measurement (optic, laser); therewith no interruption of the current supply during the measurements in the corresponding track section necessary

Optional accessories

  • LED lighting device for measurements in the dark
  • Laser glasses for better visibility of the laser point
  • Carrying bags and power adapter for more comfort
  • Measuring bars for worldwide track gauges from 750 – 1676 mm
  • Edge configuration for distance measurement from the pole leading edge to the track center

    Länge [cm]197110110