mizuki_hitoshi said: Engine brakes are pretty hard to understand intuitively, huh (^^;) Mr. Liger was printed on the back of the truck's trailer. We laughed. I guess that sort of company really is out there, huh? (lol)
Rheeve said: engine break is used with manual transmission cars, have those here in sweden too.
I'm pretty sure all manual transmission cars can do this. You just need to keep gear off neutral when you cut the gas, maybe shifting down to a lower gear.
KichiroT said: I'm pretty sure all manual transmission cars can do this. You just need to keep gear off neutral when you cut the gas, maybe shifting down to a lower gear.
I'm not sure it's called the same thing, but gas/electric hybrids do something similar, basically using the electric motor as a generator and bleeding off speed to partially recharge the battery.
Heparine said: Particularly old cars don't have it (my first one didn't), but it definitely became standard before servo did.
Well, from what I read, it's more of a side-effect of the fuel/air intake system (if you cut the gas the right way, a vacuum forms, counteracting the normal engine action. If you've got the drive engaged, that'd slow the car down as well), so I'm not sure how you can "add" it. Or maybe my understanding is incomplete. Any mechanics around?
KichiroT said: Well, from what I read, it's more of a side-effect of the fuel/air intake system (if you cut the gas the right way, a vacuum forms, counteracting the normal engine action. If you've got the drive engaged, that'd slow the car down as well), so I'm not sure how you can "add" it. Or maybe my understanding is incomplete. Any mechanics around?
Oh wait, I thought you were talking about the brake booster (that also uses the vacuum of the engine, but to multiply the force applied to the brakes, unless you run on neutral). Carry on.
As I understand it, all internal combustion engines have an engine/exhaust brake ability in some way. It is what happens when you reverse the process of feeding the engine fuel. Basically, when the engine is fed fuel, the energy from the combustion transfers through the system to the wheels producing torque and acceleration. Letting go of the gas, and forcing the engine to rev in the higher ranges (by shifting down) the energy required to keep the engine at such high revs come from the kinetic energy of the car in motion. This way, your car's kinetic energy is converted to thermal energy in the engine, which is then dissipated by the coolant system. The high revs associated with engine braking causes a lot more noise and is often banned in residential areas. Large trucks have exhaust braking, which is a kind of engine brake.
Engine braking for the most part is the use of the vehicle's driveline/powertrain to slow the driven wheels down.
Jake-brake is a way for most diesel engines to "skip" the compression stroke and resisting the driveline and wheels to turn, which slow the vehicle. Exhaust braking restricts the exhaust gas from exiting the engine at normal rate which slow the engine's ability to pull in fresh air/fuel mixture; again slowing the driveline down. Downshifting is the most popular way, selecting a lower gear ratio would allow the engine compression to "fight" the turning of the wheels. Engine braking is a way to reduce riding the brakes and possibility overheating them on long slope. Many long-haul and semi truck drivers know the important of engine brake.
Most modern automatics naturally have engine brake. Letting off the gas in drive slows the vehicles down faster than in neutral. Automatic transmissions can be downshift manually; select 2 or L at moderate speed will create a notable decrease of speed.
Some reasons why engine braking is not allow in some area is first, the noise level. Jake-braking gives off a very loud machine gun like sound which in populated area is very annoying. Sometimes ear damaging. Second is traffic safety. Engine braking does not illuminate the rear brake lights like normal service (foot) brakes. On many parts of the US interstate, road lighting is poor to none, depending on mostly vehicle lights. Because judging distance is poorer at night, brake lights are importance to communicate to other that the vehicle ahead is slowing down.
Another way to teach other about engine breaking is think about a bicycle, one with a solid chain from the crankset to the rear sprocket and wheel (No freewheel hub or slip). Think of the legs as the engine, it can push down on the crank to move the bicycle. But when rolling down hill, let the legs go limp and on the pedal. Now the wheel is turning the crankset. Add a little resistant with the legs and the wheel have to fight that and begins to loss energy.
unicode said: Pretty much how a fridge works, right? Consume energy to extract heat from gas.
In a way, but then again everything is a transfer and transformation of energy. Where a fridge uses compression to extract heat out of a coolant, engine braking uses the movement of the car to drive the engine's combustion, transforming the energy to heat. Tundra's explanation is pretty comprehensive.
ThymeParadox said: Danbooru, come for the Touhous, stay for the mechanics lessons.
Quoted for truth.
Got a little used to itSo the engine's running, but it's a brake? Ummm...Aaaah! Ahead! Look ahead of you!A Common QuestionBy the way, I've been wondering for a while...Yeees?Just where is the "engine brake" on the car?Huh?Ummm...The engine brake uses the force of the engine's revolution itself as a load to apply the brakes.Huh?