Tow Dynamometer

Tow Dynamometer
The custom-designed Tow Dynamometer is attached to and towed by any vehicle undergoing road testing. It serves two purposes:

  • When used in conjunction with WESTEST extensive data acquisition capabilities, a range of performance data can be captured from various mechanical components as the vehicle operates under loaded conditions.
  • Various loading conditions can be simulated such as hill climbing at gross vehicle weight as the vehicle operates.

State-of-the art controls connected to the Tow Dyno allow test vehicles to simulate a variety of load conditions without having to leave the safe and controlled confines of the flat test track. As a test vehicle moves pulling the Tow Dynamometer, an air-cooled eddy current Power Absorbing Unit (PAU) converts the vehicle’s kinetic energy into heat. The DAC/PC-based control system, using closed-loop feedback control, regulates the amount of load imposed on the test vehicle depending on the control method.
The tow dynamometer can be configured to operate under a variety of control scenarios depending on evaluation requirements.

Control modes include:

  • Constant velocity
  • Constant load
  • Constant power
  • Grade simulation


  • Peak power: 375 kW (500 hp)
  • Continuous power: 260 kW (350 hp)
  • Peak drawbar force high-range ratio: 15,230 N (3,424 lb)
  • Peak drawbar force low-range ratio: 32,000 N (7,200 lb)
  • Peak speed 1:1: Ratio 120 km/h (72 mph)
  • Peak speed 2.1:1 70 km/h (42 mph)
  • Ballasted trailer weight: 10,224 kg (22,540 lb)
  • Unballasted trailer weight: 8,047 kg (17,740 lb)


The WESTEST Tow Dynamometer is equipped with:

  • Adjustable trailer hitch (16 to 24 inches),
  • Standard gladhand air brake connections
  • Standard trailer electrical connector (SAE J560b)


  • Laptop computer wireless interface
  • Constant speed mode
  • Constant force mode
  • Constant power mode
  • Manual control mode

Testing Applications

  • Engine Performance
  • Drive Train Component Evaluation
  • Transmission Component Evaluation
  • Road Grade Simulation
  • Trailer Towing Simulation
  • Fuel Efficiency
  • Auxiliary Components
  • Failure Analysis
  • Vehicle Heating & Cooling Systems
  • Tire Testing