Typical Applications

Vehicle Ground Speed
Distance Measurements
Vehicle Crash Testing
Speedometer Calibrations


Powerful Torsion Spring
Extremely Rugged
Digital Pulse Output


HFW80 Fifth Wheel Sensor

Fifth Wheel

Designed for all types of uses involving vehicle speed and distance measurements, the HFW80 Fifth Wheel Sensor is accurate, reliable, rugged, and easy to use.

The fifth wheel features a high resolution optical encoder and low tire diameter growth to ensure excellent accuracy. A helical torsion spring allows a compact design and provides surface tracking by keeping the wheel in contact with the ground during dynamic maneuvers.

A powerful helical torsion spring keeps the wheel in contact with the ground at all times.

The fifth wheel is ruggedly constructed from high strength materials and precision components. Originally designed for use in the “high-G” environment of vehicle crash testing, the fifth wheel has also performed well in many less demanding applications including low speed measurements over rough terrain. It has proven reliable with a service record of over 10 years.

The output of the fifth wheel sensor is a TTL level digital pulse which may be used to measure either speed or distance traveled. Coupled with the GMH Engineering digital display, a complete measurement system is obtained. The fifth wheel also readily interfaces with most off-the-shelf digital tachometers, control systems and data acquisition systems.


  • Digital Optical Encoder
  • TTL Compatible
  • Counts available: 500 or 1024 counts per revolution
Temperature Range
  • -40 to 212° F (-40 to 100° C)
Speed Measurement
  • Range: 0 to 80 mph (0 to 129 km/h)
  • Accuracy: Better than 0.2 mph (0.3 km/h)
  • 20 ft. (6.1 m)
  • 4 conductor, tinned leads
Distance Measurement
  • 0.1 in./pulse (2.5 mm/pulse) with 500 count encoder
  • Arm, Body & Mounts: Anodized 6061-T6 aluminum
  • Axle: Heat treated tool steel
  • Pivot Pins: 303 SST
Tire / Wheel
  • ~15.5 in. (39.4 cm) O.D. pneumatic tire
  • 16 in. ABS thermoplastic
  • Overall Length: 44.25 in. (112.4 cm)
  • Swing Arm Length: 32.25 in (81.9 cm)
Tire Growth
  • Less than 0.5% at 50 mph (80 km/h)
  • 20 lb (9 kg)
      Fifth Wheel Measurements  

Mounting Plate Dimensions in Inches


Fifth Wheel Dimensions in Inches