mercedes sprinter chassis
we are downsizing from a diesel pusher to a class C. We had a tiffin before current one and the Wayfarer caught our attention, but when studying it a bit the 702 lbs carrying capacity killed it for u...
Forum Discussion
No, there is no tow/haul mode. The transmission is calibrated for hauling at all times, so it is unnecessary. As for engine braking, it is almost non-existent. This has to do with the differences between diesel and gas.
On a gas engine, the intake butterfly closes, creating a high vacuum within the engine. The computer shuts off the fuel supply, and you now have a very large, hard to turn air pump under the hood. This is what holds back your speed.
On a diesel engine, there is no butterfly, nor is there any vacuum. A separate pump is mounted to the engine to make vacuum for those systems. There is a slight braking effect from the engine, but there is no vacuum drawing down your speed. this is why you hear big rigs making a lot of noise on deceleration... the invention of the Jacobs Engine Brake (Jake Brake). It opens the exhaust valves and closes the intake valves differently in order to create vacuum in the engine. The result of this is the loud B-A-A-A-A-A-A-A-A-A-A-A-A-A-A-P when going downhill or slowing down. Yes, some abuse these just to make noise, but its actually an important safety device.
A more recent invention is the exhaust brake. These are more common on large DPs and buses, as they are nearly silent. Only a loud hiss is emitted by the exhaust, and most of that is quieted by the muffler. These do not offer as much braking effect as a Jake Brake, nor are they as long lasting and reliable (actuators get sooted up and stick, etc), which is why they are not commonly found in big rigs.
On a gas engine, the intake butterfly closes, creating a high vacuum within the engine. The computer shuts off the fuel supply, and you now have a very large, hard to turn air pump under the hood. This is what holds back your speed.
On a diesel engine, there is no butterfly, nor is there any vacuum. A separate pump is mounted to the engine to make vacuum for those systems. There is a slight braking effect from the engine, but there is no vacuum drawing down your speed. this is why you hear big rigs making a lot of noise on deceleration... the invention of the Jacobs Engine Brake (Jake Brake). It opens the exhaust valves and closes the intake valves differently in order to create vacuum in the engine. The result of this is the loud B-A-A-A-A-A-A-A-A-A-A-A-A-A-A-P when going downhill or slowing down. Yes, some abuse these just to make noise, but its actually an important safety device.
A more recent invention is the exhaust brake. These are more common on large DPs and buses, as they are nearly silent. Only a loud hiss is emitted by the exhaust, and most of that is quieted by the muffler. These do not offer as much braking effect as a Jake Brake, nor are they as long lasting and reliable (actuators get sooted up and stick, etc), which is why they are not commonly found in big rigs.
