Downgrades in the snow

An engine has compression. When you let off the throttle that compression creates a braking effect. Anyone that has driven a high performance sports or race car understands this very well. The higher the rpm you get off the throttle, the greater the braking effect. Jake brakes are like that compression braking on steroids.

If you decide to descend a LONG steep downgrade WITHOUT Jake brakes you MUST choose a gear that will allow you to descend MUCH MUCH slower than you could if you used Jakes. For example, I could use Jake's and descend westbound from the Eisenhower Tunnel at about 25-30 mph fully loaded with occasional use of service brakes. If I CHOOSE to descend without Jake brakes I need to drop a few gears to let engine compression alone control most of the descent. Then the appropriate speed will be in the neighborhood of 10-15 mph.

So the OP begs the question: why are you CHOOSING to descend without Jakes?

 

I think a better question would be how is he on his own and not able to make it down a mountain.

Maybe I'm just old, but I remember driving trucks that didn't have a jake.

 

I'm going to take a wild and educated guess that the OP didn't go through a training program after getting his CDL. Either that or he trained at a company that didn't have a good training program.

I spent a year as a trainer at Swift. Get this: they didn't want their trainees to EVER use the Jake brake during their 200 hours behind the wheel training. Would YOU want to certify a trainee without essential experience running big hills? I didn't. I always made sure my trainees knew how and when to use the Jake, how to run without the Jake, how to make ###### sure they never smoked the brakes, and how to chain up to get over a pass.

But then again many a trainer is unqualified or they drank the company Koolaid.

 

I must have been driving a tired old 12.7 Detroit. Engine compression without jaking hmm. I missed that one. I never noticed that fully loaded down Mont Eagle. But very low gear selection is key. As gears hold more torque than an engine produces.

 

One of these days there should be a three dimensional modeling or sand box created of your Coquihalla so I can understand it more exactly.

That is all I am going to write here.

Im pretty certain we can show you fellas a good grade or three down here wherever we happened to have them.

 

Mr @Kinny, notice that Mr @Lepton1 is talking about 10-15mph and you were talking about 45-50mph? There aren't many hard, fast rules in trucking. If someone says, "Never use a jake in the rain", they are telling you what they were taught, not what they know. Depending on where you are and how cold it is, the snow can differ also. In extreme cold, snow will feel like sand...you can actually get decent traction. The problem will be where you see the asphalt...that's where the ice will be. Put your tires where there is snow and you should be okay IF you are easy on the controls.

Most people who get into trouble in bad weather do so because they don't know how to be easy on the controls. Ever see that idiot on flat, dry ground that throttles up and dumps the clutch in his mega carrier truck so that the chassis twists? Idiot. Eaaaaaaasy on the controls. Easy on the steering, easy on the brakes, easy on the throttle, easy on the jake (instead of running stage 3, drop a gear and use stage 2 or drop another gear and use stage 1)

"Hey Six...what about ice?"

This post. If you can feel the trailer pushing the drive axles around, making the tractor to want to turn sideways into a jackknife, you are going too slow. You're going to have to increase your speed a bit and be buttery smooth on the controls. This will be one of those situations where the drivers get separated from the steeringwheelholders. You're going to have to really know your craft. Like I said, no hard fast rules...you have to be able to adapt on the fly.

Sounds scary, doesn't it?

The thing about icy roads is that all of the road will not be icy. There will be slick areas, normally shaded and dry areas. Also, on a curvy road, you may have to straighten the road out if possible. Hit the apex. Outside, inside, outside. This is the part that gets people in cars and rookies in trouble. Resist the urge to run in a pack. You will need SPACE. A veteran driver will give you your space, especially around a curve. You will see him stay an 8th mile behind you or more and pace you and wait for a straight before passing. In fact, he will probably go outside inside outside too. Thank him for giving you that space, it made your job easy. When you feel traction return, slow her back down (remember to be E-A-S-Y on the controls).

In our situation, it's not for the speed, it's because there will be less likelihood to lose control in icy conditions.

Luck in battle.

 

I cannot believe swift can be so stupid. If it was me up there in the seatie. Ima flipping the #### thing coming off Cabbage. You can fire me at the bottom when it's all over =) (Not necessarily you personally but a Swift Trainer...)

Our industry is in such a state. But I doubt the OP is being serious or even leaning towards trolling.

Any decent trucker worth his or her salt will be playing with the jacobs system from day one. It's FUN! They said. The most fun you can have while going downhill in your senior years.

//Teasing.... Im in one of those dangerous moods today I have to be careful this morning.

 

No, it's just the way a diesel engine works. Unlike a car, where a butterfly valve in the throttle controls the intake of an air/fuel mixture thereby creating a vacuum with closed or partial throttle, a diesel engine is unrestricted and takes in a full breath of air with every intake stroke. The amount of fuel injected into the cylinder is what determines the amount of power in the power stroke. Every compression stroke is compressing a cylinder full of air, which has considerable resistance to being compressed to almost double that of an older car (we're talking 18:1ish). If no fuel is injected, that compressed air acts as a spring during the power stroke, pushing the piston back down the cylinder thereby negating much of the resistance experienced by the compression stroke. The only real resistance you have is the friction of the moving parts throughout the drive train. Most dynos figure about a 20% loss from the crankshaft to the rear wheels...so figure that's all you have slowing you without an engine compression brake. If you DO have an engine compression brake, all it does is open the exhaust valves on the engine at TDC of the compression stroke, so that there is no rebound of the compressed air pushing the cylinder back down on the power stroke. In this way, the engine is using the resistance generated by the compression stroke to slow you down.

 

That is one reason I will never ever give up the old Iron, the true non computer airbreathing desiels. If you have unlimited Fuel and air along with compression that never weakens or a leak anywhere you have a engine that will run forever.

There have been many times Ive either abused a older engine or asked Mr Pyro to endure a little more heat a little longer until the top. For the most part those engines have come through. No complaints unless you are looking at a couple that were badly engineered and badly mated to crappy transmissions and rear ends for company use.

Edited.

Now famously silly compression figure has managed to have everyone some humor and laugh me out of the room for a while. My mistakes are strictly my own. I have a good morale and can stand to be lauging today. It's all cool.

I'll rework the figures tomorrow or something when I get to the end of that particular;ar issue on the table.

These are probably known many of you as "Old Man Moments" just insert name of the oldster affected.

 

Best advice is to watch what trucks are doing on the down slope as you’re climbing. Pay close attention to them. Also follow and mimick what the trucks going you’re direction are doing when you aproach and begin the downhill. Always remember your folloing distance make it huge!!! You have better traction in fresh snow then you do on compacted snow/ice.

As for the Jakes. Start on stage one, If you feel good go stage 2, And then stage 3. Watch your rpms, to high or to low could cause you to break traction and spin wheels.

Keep your traction control on. Only shut it off if you’re spinning wheels while trying to accelerate. (Mack has the traction control as a “Mud/snow button, i can see where someone who doesn’t know anybetter would think “well i’m in snow so i should flip my mud/snow switch)

Edit: i can attest to the fact if you begin to spin wheels while the jakes are on, your traction control will kick in and shut the jakes down. The Mack i used to drive was horrible for that. Lol. That’s a good thing tho