Re: MAN launches CLA BS-IV compliant bus chassis in India Quote:
Originally Posted by blackwasp Retarder - heavy vehicles like buses and trucks have a secondary brake to improve the life of the conventional friction brakes.
AFAIK there are 2 types-
1. Hydraulic - here oil (or hydraulic fluid) is pumped into a chamber with vanes. This causes additional drag slowing down the driveshaft. These are silent.
2. Electric / Magnetic - Electromagnetic induction is used to slowdown the drive / axle by supplying it with an electric current...
Engine valve brake - Here, the one exhaust valve is kept open in the compression and the expansion stroke to slowdown the engine... |
So these basically work by increasing the engine braking?
The first two seem to be independent of the actual internal combustion process and more to do with the drive shaft rotations. By reducing these rotations, the drive power supplied to the wheels is greatly reduced which should help lose speeds quickly.
If that is correct, what happens when the retarder swings into action while the engine is still rotating at higher RPMs? Or does this all work only with the foot off the accelerator?
Regarding the exhaust valve, does it mean that the exhaust gasses are retained or fed back into the combustion chambers to retard the combustion process itself? If so, any ill effects on the engine? |