ISO 13044-2 in its current draft describes ACV (ACS / FACS) as a system designed for 24 V operation only; however, most modern brake systems (as considered by UN R13) can be operated under different voltage levels (8-32V).
The various working documents submitted for this meeting were discussed in detail. For the outcome of the discussions, please see document ACV-06-10.
Provisions for mismatching between 12/24 volt
The group went through the 12/24v document from Jost. In Australia most trailers are 12v. The group concluded that this working group does not need to make mention of this at all as the situation is not critical.
Measuring response time
Jost made some measurements. Response time of an ACV is lower than with a helix cable. When we are measuring with a simulator, we have to measure the supply system. We need a set of rules for the conventional system (annex 6) and a set of rules for the automated system.
If volume L in annex 6 is left then we have a problem. A valve adds 0.06s. We need to change the volume in annex 6 for the automated system.
If the connection line between truck and trailer is different then this must be taken into account. We actually need a longer length.
The group agreed that the method as outlined still applies but there are open issues:
- Is there room for a different value of L? If the volume L is changed then it must be changed in the calibration also.
- Timing is a secondary issue. We know the measurement is good but we don’t know how it should be changed.
Solid connection of hoses
This item was not discussed.
A point for the next meeting : think about a manual button that would make the driver leave his cab.