FM4-LO | Laser Optics

The Overhead line position measuring device FM4-LO is specially developed for the manual measurement of contact wire height and contact wire position (horizontal - and optional vertical - position of the wires in relation to the middle of track).

It measures quickly and comprehensively by using:

  • laser,
  • target optics (crosshair / optical lot) for quick targeting of the wire
  • and measuring bar scale.
For use in light rail
For use in long-distance rail

Applications of the overhead line equipment

  • 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




    • Quick and easy application to measure the catenary wire position
    • position determination of the catenary, the static rest position of the contact wire electric railways
    • statically-punctual measurement of the contact wire height above top of the rail catenary stagger measurement (zig-zag run) in relation to the track center
    • further vertical distance measurements (suspension cable, bridge height, crossing power lines)
    • use for erection of catenaries, assembly of and maintenance work on overhead contact lines

    Designed for building sites 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

    Flexibly to combine

    • partable (2-parts) measuring bar with carrying bag for easy and protected transport in the car
    • measuring bars for other track gauges or universal for several track gauges from 750 mm to 1676 mm
    • measuring bars with imperial units (ft, in), changeover of units in the measuring instrument
    • measuring device for track elevation
    • catenary lighting device for night or tunnel work
    • charger for rechargeable batteries
    • laser visibility glasses

    Measuring Bars

    Universal Measuring Bars

    partable [mm] gauge track: 750 to 1676 m, mm-scale


    non partable [mm]gauge track: 750 to 1676 m, mm-scale


    Measuring bars with fixed gauge track width

    partable [mm]

    gauge track: 1435 mm, mm-scale


    partable [inch]

    gauge track: 1435 mm, inch-scale


    non partable [mm]

    gauge track: 1435 mm, mm-scale


    non partable [inch]

    gauge track: 1435 mm, inch-scale


    non partable [mm]

    gauge track: 1000 mm, mm-scale


    Additional Acessories

    LED flashlight for catenary

    bracket with LED flashlight and brake


    additional measuring device

    additional measuring device for track elevation, height adjusment with scale 0 to 200 mm, mounted on a measuring bar

    aluminium casealuminium transport case for FM4-LO, acessories and documents99.53717
    carrie case for partable measuring bar

    padded, two carrying straps, one shoulder strap,
    dimensions appr. 105 x 28 x 18 cm


    carrie case for narrow gauge measuring bars

    padded, two carrying straps, one shoulder strap ,
    dimensions appr. 165 x 28 x 18 cm

    laser visibility glassesimproves the visibility of the red alser dot99.50968
    charger (UC20)input 100-240 V (AC), including four power adapters for worldwide use and two AAA batteries99.74089




    Stagger of the overhead contact line

    Measuring bar (guide rail) for track gauge [ft/in]1435
    Separable (two-part) measuring bar, carrying bagnoyes
    Mesuring range left to right / scale value of measuring bar [in]± 1 (1/8)
    System measuring accuracy [in]± 1/4
    Height of the overhead contact line
    Measuring range of the laser [ft]up to 200
    Factory setting / optional unit settings [ft]0.00
    Measuring accuracy laser / system [in]± 1/16 / ± 1/8
    Laser class (international standard IEC60825-1)2
    Laser power / wavelenght [mW/nm]< 1 / 635
    Direction laser beamvertical
    Display [mm]35 x 18, automatically illuminated
    Operating modessingle or contnuous measurement
    Automatic laser switch off [s]90
    Power Supply [V] DC1.51.2
    Quantity / type of batteries2 / AAA2 / AAA
    Rechargeable batteries, charger incl. 4 diverse plugsneinja
    Automatic power switch off [s]180
    Operating time / number of measurementsup to 5000up to 4000

    LED illumination crosshairs target optics)

    LED illumination for stagger measuring edgeyes
    LED illumination lighting device for contact wirenoyes
    Temperature range operation / storage [°C]-10…+50 / -25…+70
    Protection class (DIN EN 60529)IP64
    Dimensions / Weights

    Dimensions / weight of the measuring instrument [mm / kg]

    258 x 108 x 101 / 2.2
    Dimensions / weight of the measuring bar [cm / kg]187 x 21 x 14 / 5.2187 x 21 x 14 / 6.0
    Dimensions / gross weight of the transport case [cm / kg]54 x 15 x 24 / 5.554 x 15 x 24 / 6.0
    Dimensions / gross weight of the carrying bag [cm / kg]-105 x 28 x 18 / 8.0
    Dimensions / gross weight of the shipping package [cm / kg]197 x 37 x 37 / 15110 x 37 x 37 / 18