How steep a grade...

[Brewerbob]

How steep of a grrade do you have to have before your aerodynamic brick becomes a runaway? Coming back from WV the grades were as steep as 7% per the signage. At 55mph, I never gained more than 2 or 3 mph on the grades. Was the retarder in my tranny doing something? It didn't down shift. I was actually hoping for a bigger build up in speed to get back up the other side.

[turf]

your sideline says you have an MT643. thats a locking transmission in 3 and 4th i believe. you can slow down or downshift and not runaway.

the AT545 does not lockup and has very little ability to hold you back, so a long 5% grade could be problematic with a different transmission.

a retarder is a separate device. it has a control on how much "retardation" you apply to the driveline. it would have hi-low knob or a 1-5 setting.

[jctrembly]

Sounds like you came across I-68 on your way home. That's my area, our bus Normally​ have an exhaust break, which is just a butterfly valve in the exhaust to increase back pressure. They are either on or off no levels to choose from as the case with a Jake brake.

You could add one to your bus but is does cost a little to do so. Anytime you think your brakes are getting warm, find a safe spot to stop and check them. If you see smoke coming off your brakes, they are already hot and they need to cool off.

Coasting down a hill to pick up speed to go up the other side is a good deal, just watch your RPM's as you can over rev your engine and not realise until some gets expensive.

The best braking method for going down a hill is to gear down, and use light consistent brake pressure. You can bring in down to 5 mph below your ideal Engine RPM and let off the brakes. However, you don't want to get on your brakes slow way down, release your brakes and pick up speed. That cycle actually increases your brake temp more than the light consistent pressure.

The truck I drive now has the 8.3l replacement​ with an exhaust brake. It does pretty good. When it's broke down the sub trucks never have exhaust brakes, so have go to go down hills alot slower and use all the weak Engine braking I can get. At that point I'm normally near max weight for that truck too.

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[cowlitzcoach]

I drove harvest truck for several seasons going from the processing plant in western WA and the corn/carrot fields in the Columbia basin in central WA. It required going back and forth across White Pass on US12. The top of White Pass is 4000' and the bottom on the western side is less than 1000'. A 3000' drop in seven miles can be a bit of challenge when you throw in the fact it is a two lane highway with lots of twists and turns.

One night heading back to the plant with a full load of fresh corn on board, 105,500 lbs. give or take 1,000 lbs. I went over the crest of the pass and went to hit the jakes for the first curve on the downhill side. Needless to say I went into full pucker factor when the jake did not engage.

Going down a steep hill with a lot of curves in a gear or two higher than what you would be in if you didn't have a jake brake is more than a little bit disconcerting.

Fortunately the road levels out in places which allowed me to start dropping gears before I got to the next steep portion.

I would never have gone over the crest in such a high gear if I had any inclination that the jake was non-op. It had been working on the trip east and so far on the trip west. Leave it to Murphy to apply the law to the steepest down grade of the whole trip.

So instead of a gear that would keep me in the 35-40 MPH range I was a couple of gears lower in a gear that would keep me in the 25-30 MPH range.

[Brewerbob]

Originally Posted by turf

your sideline says you have an MT643. thats a locking transmission in 3 and 4th i believe. you can slow down or downshift and not runaway.

the AT545 does not lockup and has very little ability to hold you back, so a long 5% grade could be problematic with a different transmission.

a retarder is a separate device. it has a control on how much "retardation" you apply to the driveline. it would have hi-low knob or a 1-5 setting.

I meant locking or whatever mine has. On the way to the storage lot it seemed to accelerate down hill more. Steeper but shorter hills.

[EastCoastCB]

Runoff ramps are scary on a maiden voyage.

https://www.youtube.com/watch?v=W5PZvtSvp9s

[Brewerbob]

Originally Posted by jctrembly

Sounds like you came across I-68 on your way home.

I did.

You could add one to your bus but is does cost a little to do so. Anytime you think your brakes are getting warm, find a safe spot to stop and check them. If you see smoke coming off your brakes, they are already hot and they need to cool off.

Trying to go faster, not slower.

Coasting down a hill to pick up speed to go up the other side is a good deal, just watch your RPM's as you can over rev your engine and not realise until some gets expensive.

Drop to neutral then.

The best braking method for going down a hill is to gear down, and use light consistent brake pressure. You can bring in down to 5 mph below your ideal Engine RPM and let off the brakes. However, you don't want to get on your brakes slow way down, release your brakes and pick up speed. That cycle actually increases your brake temp more than the light consistent pressure.

I don't have a temp gauge but I doubt my brakes were warm much less overheated. I stayed off of them.

[jctrembly]

Going down I-68 empty I doubt your brakes became very warm either. When I reply, I don't direct it any anyone individual but just to put it out as general info. I've seen trucks on I-68 catch fire and burn to crisp due to over heated brakes. Depending on where that happens it really screws up traffic for about 6hrs as there are places where you just cant bypass with a truck.

I've seen many other trucks on I68 have smoke just rolling from there Axel's while the driver is talking away in there cell phone oblivious.

I live on a mountain here in WV and we have a 9% grade when we go west. Yes, we lose truck drivers on that section even with warning signs, runaway truck ramps and the like. Heck, untill recently we would have people ditch there cars when they got scared. 4-wheel disk brakes seems to have reduced that, now they just warped there rotors due to the heat.

The school bus here all have exhaust brakes, it's easy to get addicted to them as with a Jake you can travel down a grade faster safely with one than w/o one.

Some of the new electronic automated manual transmission drop into netrual when a truck is going down a hill for fuel savings. The tranny will reengage when a Jake brake is used or a certain speed is exceed or when you need power. I have yet to drive one of those trannys but in time I'm sure I will.

Some folks just don't think about over speeding a Diesel as Diesel Engine has a much smaller RPM range, it can cause some concerns when one goes to put a transmission back in gear only to find out the vehical speed is too fast and when it does "drop" back into gear your at the red line.



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[jctrembly]

Originally Posted by cowlitzcoach

Needless to say I went into full pucker factor when the jake did not engage.

I guarantee you did! I was in an old loaner truck and a wire came loose from the Jake. I wasnt close to your situation but it really made me think about how to handle that situation should it have became a problem. I'm glad you were able to stay safe.


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[Brewerbob]

Originally Posted by jctrembly

Going down I-68 empty I doubt your brakes became very warm either. When I reply, I don't direct it any anyone individual but just to put it out as general info.

NO worries. No offense was taken.

I've seen trucks on I-68 catch fire and burn to crisp due to over heated brakes. Depending on where that happens it really screws up traffic for about 6hrs as there are places where you just cant bypass with a truck.

I've seen it too and tried to alert the driver but without a CB...

Some folks just don't think about over speeding a Diesel as Diesel Engine has a much smaller RPM range, it can cause some concerns when one goes to put a transmission back in gear only to find out the vehical speed is too fast and when it does "drop" back into gear your at the red line.

My redline is 65mph, so long as I'm not above that when I drop it back into gear I should be fine no?

[cadillackid]

ive run my DEV bus over I-68 a couple times... I just did general common sense measures... let the bus slow down on the uphills and didnt try to race.. and then let it do its thing on the downhills startimg out at a slow speed... knowing the terrain was a help... ive run 68 a bunch of times over the years in various cars...

every now and then I did the stab and go... drop the speed a quick 5.. I did allow the bus to slowly speed up as an overall from the time I started to the time I ended up at bottom.. so thats "free energy to expel"...

I see some of the truckers keep their foot to the floor up and over the top and then still on the gas t oget "up to speed" as they start down the grade rather than continue to go slow and let gravity speed them up... those are the ones I usually smell brakes later on.
-Christopher

[jctrembly]

Yes, stay under 65 when you engage your transmission and your good. 😀

Unfortunately, Less and less trucks have CB's and many of the ones who do seem to keep them turned off until they are stuck in traffic. At times it's quite funny as I'll hear about a jam up, bypass it on the skinnies and there is always alot folks complaining​ about being stuck. The only good thing about less CB usage is alot less knuckle heads talking filth.

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[Brewerbob]

Originally Posted by cadillackid

ive run my DEV bus over I-68 a couple times... I just did general common sense measures... let the bus slow down on the uphills and didnt try to race.. and then let it do its thing on the downhills startimg out at a slow speed... knowing the terrain was a help... ive run 68 a bunch of times over the years in various cars...

every now and then I did the stab and go... drop the speed a quick 5.. I did allow the bus to slowly speed up as an overall from the time I started to the time I ended up at bottom.. so thats "free energy to expel"...

I see some of the truckers keep their foot to the floor up and over the top and then still on the gas t oget "up to speed" as they start down the grade rather than continue to go slow and let gravity speed them up... those are the ones I usually smell brakes later on.
-Christopher

From all the brake fires and scare stories I just assume someone is freewheelling a hell of a lot more than me. On that route even cresting at 55, I only gained 3 maybe 4 mph tops. Was wondering if that is a result of my tranny, being a flat nose, etc. No one, even the cell phone talking trucker is lighting anything on fire or going over a guard rail because of +4mph.

Not knowing the road, being dark, raining and crappy headlights there was only one curve that I was a little nervous about. Never hydroplaned and never felt the wheels slip so it was for nothing.

[jctrembly]

No so much from freewheeling but from being heavy, going to fast (too high of gear) not using the engine brake, and lack of training and/or lack of concern.

Would you believe some of these fleet's today still spec trucks without an engine brake of any kind. All to save a few pennies.

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[cadillackid]

Originally Posted by jctrembly

Yes, stay under 65 when you engage your transmission and your good. 😀

Unfortunately, Less and less trucks have CB's and many of the ones who do seem to keep them turned off until they are stuck in traffic. At times it's quite funny as I'll hear about a jam up, bypass it on the skinnies and there is always alot folks complaining​ about being stuck. The only good thing about less CB usage is alot less knuckle heads talking filth.

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the internet... I keep the tablet mounted to the dash that shows me the traffic in real-time... one screen was WAZE up, the other screen has the Co-Pilot truck GPS with realtime traffic... I never have to touch the screen I just glance when it flashes and can talk voice to it if I wish to re-route... seems to be better than listening to all the pussy-craving truckers on the CB..

-Christopher

[turf]

not to poke the bee's nest or anything....

i think the next colorado get together need to be near the bottom of some pass. Lake Granby or somewhere in the high country that requires at least one big downhill no matter which way you get there.



you know, so we can talk safety!

haha, i had to goggle what a cb was. i forgot

[EastCoastCB]

Originally Posted by jctrembly

Yes, stay under 65 when you engage your transmission and your good. 😀

Unfortunately, Less and less trucks have CB's and many of the ones who do seem to keep them turned off until they are stuck in traffic. At times it's quite funny as I'll hear about a jam up, bypass it on the skinnies and there is always alot folks complaining​ about being stuck. The only good thing about less CB usage is alot less knuckle heads talking filth.

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all I've heard on CB's the last decade are foreign voices and languages, and bit of lot lizard banter.

[EastCoastCB]

Originally Posted by cadillackid

the internet... I keep the tablet mounted to the dash that shows me the traffic in real-time... one screen was WAZE up, the other screen has the Co-Pilot truck GPS with realtime traffic... I never have to touch the screen I just glance when it flashes and can talk voice to it if I wish to re-route... seems to be better than listening to all the pussy-craving truckers on the CB..

-Christopher

THIS^

[jctrembly]

Lol, love it turf!

Waze is a great Tool, but you can't follow it for a truck blindly, and you have to be careful even with a bus due to height, length, weight restrictions. Many folks dont realize all the truck restrictions until you drive a truck.

Trucking GPS's have alot of fake restrictions in them also. For example US40 starting at the Eastern of the PA/MD line to Uniontown PA shows a 10 ton weight limit. But it's not, they want the trucks to go across I-68 and then take the PA Toll road up to Uniontown. I've seen the same thing in many other states. That causes the truck GPS to reroute a truck down roads not intended for trucks and then the locals complain about trucks on those very roads. I set my truck GPS for height and leave the weight at 5 tons. Before i was dedicated I kept state maps to verify weight I limits. Even I. WV we have many truck restrictions on our roads that a GPS will follow, but only 1 in 15 are posted. If it's not posted, it's not applicable, but it does keep those GPS following trucks well away.

Heck, a large portion of side roads in PA have a 10 ton weight limit. I know many of us can easily beat that when loaded. PA did this due to the gas well fracking. Honestly, in the bus I could careless about those signs, but if something happens that would be an easy fine add on..

That sorta happend me to in NYC. I hooked an illegally parked car on a corner with my trailer ICC (rear) bumper. It was on my blind side, very tight intersection, and he was right on the corner. In NYC illegal parked car = his fault. I did get an "out of truck route" ticket though. I was a street off of my destination since I missed the turn, a had to go up that street due to the elevated subway I couldn't​ fit under and a slew of cars behind me. Needless to say, it ah, yea it messed up his car pretty good. The first thing the guy said to me was, well eveyone told me not to park here. Lol.

Other than the ticket (with points, but not in WV) the NYPD were pretty cool, but they had no idea how to get me out of there due to the cross cross of the elevated subway lines. I was much more careful going to that small manufacturer from then on.

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[turf]

i have an "rv" gps and if you have it on that setting, it will send you on some crazy routes.

i got kicked off I-70 and 300 mile detour because i followed the gps. the gps said i-70 was closed because i was on the rv setting. no reason why its closed, just closed. on the way home i turned the gps off and went through. the point the gps noted for the restriction was a 12' wide bridge construction zone,not a closed road.

i miss maps

i have a drawer full of them.