1. Findings / Comments On-road test procedure (1/2)
On-road test depends on weather conditions (seasonal dependency)
Driving 85km/h over a representative distance requires a closed test track with a straight line more than 2km to ensure:
constant speed level
constant fuel flow
constant operating behaviour of the auxiliaries
The straight line on which the test takes place needs to be plane
If the test track is not designed as a round circuit:
40t long haul trucks are to warm up on puplic roads (highway)
A distance between highway and test track causes a temperature drop on the powertrain before the measurements
Opportunities to turn the vehicle in large radii are required for not stressing the Kistler rims
After warming up the vehicle for 2 hours the Kistler rims must be calibrated
temperature drop of the rear axle
Temperature drop of the powertrain during each lifting

2. Findings / Comments On-road test procedure (2/2)
High effort for lifting the loaded rear axle regarding the Kistler rim calibration
On test tracks without a closed workshop the rear axle needs to be lifted by pneumatic jacks. Two more trucks are necessary to provide the needed air supply not to demand the air compressor of the test vehicle.
Contingent on Kistler rims
Long delivery periods
High acquisition, calibration and repair costs
Highly sensitive measurement system
Calibration of required measuring equipment have to be kept up to date(costs, efforts)
Measuring errors of measurement instrument are causing a difference between VECTO and recordings
No blockade in the running research & developement on chassis dyno

3. Findings / Comments Chassis dyno test procedure (1/2)
While doing measurements for CO2 certification chassis dyno are blocked for research&developement projects. It hinders the company in developing consumption optimized vehicles. Delays occure by bringing innovations to serial.
Running the vehicle on chassis dyno in its most relevant operating points for more than 3 repetitions oils of driveline components reaching their maximum allowable operating temperature.
After a warming up and running the vehicle for 3 times ambient temperature at non air conditioned chassis dynos is reaching levels where the „tropical protection“ of trucks is working (seasonal dependency)
A power reduction occurs
Lifting the rear axle on chassis dyno for calibrate the Kistler rims is impossible without any crane or wheel loader.
So for each lift the vehicle needs to be taken of the chassis dyno
repeatability is getting lost
Companys with an 1-axle chassis dyno are not able to measure 4x4 – vehicles and articulated busses

4. Findings / Comments On-road test procedure (2/2)
Contingent on Kistler rims
Long delivery periods
High acquisition, calibration and repair costs
Highly sensitive measurement system
Calibration of used measuring equipment have to be kept up to date (costs, effort)
Measuring errors of measurement devices are causing a difference between VECTO and recordings
Measuring errors of all the required equipment (Kistler rims, flow meter) need to be taken into consideration
The control of chassis dyno and vehicle itself has an impact on results. On a 1-axle chassis dyno the vehicle registers the front wheels are not moving and sending error messages regarding plausibility.
It not depends on weather conditions like rain, wind or snow