I have been googling this for 10 minutes and it seems the same to me. Are both methods not just using the air from the intake to add more resistance to the pistons and crankshaft?
In: Engineering
Yes, but how they operate varies.
A regular gas vehicle engine mostly works on the principle that there’s a near-vacuum on the intake (which is controlled by the gas pedal) whereas the output via the exhaust is at full pressure. So there’s naturally pressure there against the engine spinning and no matching pressure to help speed it up.
A diesel vehicle has a very different fuel system, and so Jake Brakes work differently. Instead, when the cylinder is at the point where ignition of the fuel is expected to happen with the air in the cylinder fully compressed, the exhaust path opens prematurely as a secret escape hatch allowing the air in the cylinder to escape. Engine momentum was spent compressing the air, but with the air escaped it does NOT help press against the cylinder again for what would be the combustion/power stroke. It basically makes the engine work as an air compressor and letting all the compressed air out, which is why it makes that distinct noise and why you see signs on the road like “Avoid use of [unmuffled] engine brakes]” for the noise.
Latest Answers