Bking:
cav551:
Try reading that again and then THINK. Of course HGV have a secondary brake. The question was asking: what do you have to do to operate it, use the hand valve or the footvalve? Others seem to have understood that point and also that not all manufacturers go about doing things the same way. Now with your infinite knowledge of everything maybe you can answer the question, Daf hand or foot? Renault hand or foot? etc. The clue being whether the tester asks for the secondary brake to be operated on RBT.Secondary brake is the application of air to all chambers before the hand valve is fully applied.
When the hand “brake” is fully applied air is dumped from the spring brakes.
The secondary brake is in reality using the hand valve as a footbrake.
Thats why the hand valve only exhausts as you pull it over the lock point.
Try it.
I dont think its as simple as that between the different makers.
As an example Daf on the pit footbrake on then apply handbrake = release of air.
Scania on the pit footbrake on then apply handbrake no air at all just the click noise the handbrake being applied
Daf 4x2 tractor up to 63 plate on the RBT no secondary, Daf 4x2 Euro 6 64 plate onwards on the RBT secondary on drive axle only.
Scania 4x2 tractor on the RBT 65/66 plate no secondary either axle.
Merc 4x2 tractor on the RBT secondary both axles and a royal pita to get a pass first go!
Plus it doesnt stop there as different chassis/wheel configs and markets all have different specs, also changes between model years soemtimes in the same year.