Engine braking vs foot braking in snow/Ice.

Driving in slippery condition, If you know the safe speed of the corners you will have to negotiate, that is the speed you want to go down the hill unless you know you can slow down before that corner. Using a Jake works OK if used in say 2 cylinder position, at lower RPM. If you have to, brake slow and steady all the way down the hill stab breaking will put you in the ditch. If the hill is well traveled you will have two polished tracks and there is more traction in the snow build up area in the middle of the lane, and edges of the road.
In a car you want to practice going to neutral without looking. When the vehicle is cold and at fast idle, and you want to stop put it in neutral and use the brakes, especially in the area of an intersection where the ice is polished. Try it in a parking lot. Do not use neutral at any great speed. Slow and steady wins, not to slow that every rut will throw you around, not to fast that you slide of the road. Knowledge of the road, is important to make any time when it is really slippery, Know when to speed up to run a hill without having to put down to much power, and when to slow before a crest of the hill. Know when you have to put on chains, so you do not cause problems for other people

 

Keep off the Jake,use light pressure on the brakes.Modern tractor trailers have ABS which help in snow.

 

Another important distinction between automobiles and trucks is the difference between gasoline engines and diesel engines.

In both cases, shifting to a lower gear results in higher engine speed. However, in a diesel engine, this does NOT result in a slowing of the vehicle like it does with a gasoline engine because of the differences in which these two engine types operate.

Gasoline engines have a throttle, which controls the amount of air entering the engine. With your foot off the accelerator, the throttle closes, and the resulting vacuum of the piston trying to suck in air results in a braking effect.
Diesel engines have no throttle - they vary power by adjusting the flow of fuel. With your foot off the accelerator, air still continues to flow into the cylinders.

"Engine braking" does not exist in a diesel engine without Jake brakes. Rather than trying to suck in air against a closed throttle, Jakes operate by releasing the combustion gases that would normally force the piston downward in the power stroke. Without those gases expanding in the combustion chamber, the piston works against itself (against the air below it) as it continues its cycle. This causes the braking effect.

There are also systems which impede the flow of exhaust gases from the cylinder, creating more pressure for the piston to work against.

 

All good answers.

In addition, a car does not have a hinge in the middle with 75% of the weight behind that hinge riding on 45% of the rubber. Basic physics will tell you not to mess up the balance of this suddenly on slick surfaces. Any method that can be used to avoid messing up the balance is a good idea. Since engine brakes cause a sudden shift in power distribution, forcing the balance of that weight forward on the entire setup, the vehicle will be much more likely to break loose. This is a bad thing. Regaining that balance can be a real challenge. That's why jakes are generally avoided in slick conditions.

You can get away with a lot more in a car for the reasons outlined above and because cars have a lower center of gravity. Despite this, trucks are more stable in wet or wintery conditions because of having more rubber and weight to the ground. That's why you see cars spinning out on ice and snow before trucks.

Excellent question.

 

15% is the point of no return......

 

keeping the jake off prevents the tractor from slowing down too much, causing the trailer to swing out....

so keep jakes off.....

i question the "light brake pedal" as there will always be one set of brakes NOT in proper adjustment to all the others. when that wheel locks up (and it will) jack-knife will occur..normal brake application/pressure (by your foot) is what is to be used. (non abs trucks, or non working abs brakes)

as for cars with automatics...??

descend any hill in 2....this gives you torque and enough braking power from the engine/transmission.......in fact, you can climb the hill in 2 as well, and use steady gas pedal pressure, to avoid wheel spin out.

if an automatic car has over-drive, shut that off, as the wheels will slip causing the transmission to hunt for a gear to be in.......and can cause over speeding on the slippery surfaces. drive on slippery surfaces in DRIVE only, dis-engage the over-drive, again, hunting of the gears will take place.

 

I said to keep the Jake off,Light brake application, in my opinion, allows the ,brakes to apply more evenly.Could be wrong,but it's worked for me the last 30 years in extreme winter conditions in New England.

 

with a constant light pressure on the brake pedal, if a set of brakes are not adjusted properly, you risk jack-knifing, as well as over-heating that set of brakes. but do as you wish, i too live in New england....so what..??? New England, Rocky Mountains, Cascade Mountains, Blue Ridge Mountains....we here in New England are no more "blessed" than one thinks we are......

 

Please show me where I said constant ? or about using a Jake ? I'm sorry that you have a problem with comprehension.Also didn't know that this was a pissing contest.

 

"light brake application" is the same as steady/constant pedal pressure. as YOU didn't specify the exact way you meant, "light"...does that mean you "lightly apply the brakes"..as you are trying to stop....??? and if YOU READ IT RIGHT, i never said that you had the jakes on.....