Frequently Asked Questions
Question:
Why is the Vericom more accurate and more repeatable than other competitive brake testing devices?
Answer:
The Vericom has unique algorithms referred to as Run Duration Protocol (RDP™). Most other devices require the operator to decide when the run starts or stops. Most accelerometers devices choose zero G or -0.2G as the stop point, which will cause up to a 0.230 second error. This would be a 10% error for a typical braking test. RDP produces an objective calculated drag factor (f). All other devices produce a subjective f because the elapse time of the skid test is estimated by the user.
= Run duration protocol (RDP™)
= Point of activation threshold
= Point of termination recognition
Question:
How do I justify skidding a vehicle to determine drag factor?
Answer:
- Newton’s second law of motion says so.
- SAE Standard J2505 says so (June 2003).
- Drag sleds do not give the same number as the Vericom. The best you can expect with a drag sled is a number within 20% to 30%.
Question:
Can I prove the Vericom is accurate?
Answer:
Yes, by comparing the calculated speed of the Vericom with any known speed. The VC4000DAQ, VC4000PC and the VC3000DAQ have appendage speed devices available.
Question:
Can I prove I used the Vericom correctly?
Answer:
Yes, by comparing the calculated speed of the Vericom with any known speed. The VC4000DAQ, VC4000PC and the VC3000DAQ have appendage speed devices available. By confirming the speed you have proven the Vericom is accurate and you used it correctly.
Question:
If I am using an exemplar test vehicle to measure f should the test vehicle be equipped with ABS or stand brakes.
Answer:
Normally using a vehicle with ABS is recommended, when the ABS drag factor is 0.85 ± 5% or higher, then you can predict a standard brake drag factor to normally be 0.75 ± 5%. If some doubt does exist then use an exemplar ABS vehicle if the vehicle involved in the accident has ABS and use an exemplar vehicle with standard brakes if the accident vehicle has standard brakes.
Question:
What about f for a Critical Speed Yaw (CSY).
Answer:
To measure a drag factor for a CYS use a test vehicle with ABS. This is true if the accident vehicle is equipped either ABS or standard brakes.
Question:
Is there a normal range for drag factor?
Answer:
Drag factor should always be measured because the road surface can change and the type of vehicle can make a difference. However about 80% of the time drag factor is predictable when we categorize exemplar vehicles as follows:
| Vehicle |
drag factor |
| Passenger vehicles with standard brakes |
0.75 ± 5% |
| Passenger vehicles with ABS |
0.85 ± 5% |
| Passenger vehicles with high performance tires and brakes with ABS |
0.95 ± 5% |
| Motorcycles |
0.90 ± 10% |
| Commercial vehicles |
0.62 ± 10% |
| Pickup trucks are 5% less than passenger vehicle |
|
Question:
What are the advantages of Profile Professional software?
Answer:
Profile Professional software is a powerful graphing software that does tables, line graphs, analog meters, overlays and does calculations with range tables. It allows you to analysis, compare and store the data. Profile Professional software is designed for courtroom presentations. It is an essential requirement for comparing ABS to standard brakes and lateral G applications. Profile Professional software is included with the VC4000PC, VC4000DAQ and RFM4000.
