Braking/OverDrive Options when dealing with steep incline/decline

[braduah]

Awesome folks of RVforum....

Based on experience, what is the best way to handle hills/mountains when traveling?  I'm new to rv'ing and trying to understand the best way to let the engine provide the braking vs 'riding' or 'pumping' the brakes.  Below are the Engine/Tran Specs of the unit..

V-10, F-Series Super Duty
320 hp @ 4,750 RPM
460 ft-lbs @ 3,250 RPM
Gas, 6 speed automatic with Overdrive

Any input for this newbie would be much appreciated!

 

[Mothership]

Don't be afraid to use your transmission!

Shift down a gear or turn off your overdrive for long downhill runs. I will use lower gears for stops also. Start downhills slowly and keep it slow and steady. Once you gain speed and momentum it's hard to slow with just breaks. Keep in mind if you do overheat the breaks they loose efficiency, they will fade and the break components can be damaged.

 

[Lou Schneider]

Commercial truck drivers are taught to use the transmission as the primary braking device going down a hill.  Shift into a lower gear and let the engine rev up to hold the rig back.  Brakes are used sparingly, if at all, to avoid overheating and fade-out.

Interstates and other major highways in mountain areas have signs at the top of long downgrades, telling you how steep and how long the descent will be.  It won't take long until you learn that you can descend a 4%-6% grade at or near the speed limit without using the brakes by turning off the overdrive or downshifting by one gear and letting the engine speed up while a 7%-8% grade means you'll have to go more slowly and use a lower gear.  These are just examples, the actual performance will vary according to the characteristics of your rig.

Don't be afraid of going slower than the speed limit down a long and steep downgrade.  That's what the right hand lane is for and trucks will be doing the same thing.

Modern automatic transmissions won't let you harm the engine by over revving it - if the engine speed gets too high they'll automatically switch to a higher gear.  This can be thrilling if it happens while you're in the middle of a steep downgrade because you'll lose a lot of the engine braking force. 

The response is to hit the brakes hard and quickly slow down until you can shift the transmission into a lower gear than the one you were using. 

Likewise, automatic transmissions won't shift into a gear that will harm the engine, even if you select it.  Once the speed is reduced to where the transmission can shift into the lower gear the engine will then resume holding the rig back.

And certainly don't continuously ride the brakes on the way down.  Even light brake pressure over a long period of time will overheat the brakes.  If you do have to use the brakes, brake firmly until your speed drops by 5 -10 MPH, then get off of them and let them cool before the next application.

 

[jackiemac]

Our truck can be a little noisy at times.  My other half looked up you tube for some tips on the driving and that helped us a lot. 

 

[DearMissMermaid]

If you have the original Engine Manual, by all means read it!

Mine explained all about overdrive, brakes, uphill and downhill mountain driving as well as tons of other useful info.  ;D

It explained the max MPH for shifting down on mountains etc. Anyhow, I ran over the mountains several times now, and I just follow the manual recommendations and my own common sense.

At one point I had a well-meaning friend traveling with me who thought they were going to bully me into their way of thinking and driving, until *ahem* I showed them the engine manual from Ford that clearly explains the best and safest way to handle the rig in unique situations. They actually came around to the "new" way of thinking.

So read the manual, and if you don't have one, download and print it.

Another friend just bought a PleasureWay and it had no manual. They were asking me about mountain driving, so I downloaded and printed the manual for them. Then we went to Office Depot who let us use their 3 hole puncher. We were able to find a notebook to fit it all and now they are studying their manual.  ;D

 

[KandT]

So to ask a related question...  I put my MH in tow/haul as soon as I start out.  When I take my foot off the accelerator, am I being slowed by the engine? 

I can descend a fairly descent highway hill without needing the brakes and I assumed it was simply the inefficiency of the MH - wind resistance etc. but as I read more I am wondering if the e450 isn't setup to start engine braking as soon as a foot is off the acccelerator at least on a descent.

I am surprised at how well that engine does slow the MH and downshift when in tow/haul.

 

[Mile High]

Let the engine do the braking, but don't let it over-rev.  With my gassers I would find a spot on the tach that I wouldn't let it go over, and when it got there I do a hard, short, braking to bring the speed down and start all over.

 

[KandT]

What is considered over rev?  On the downhill I will let it hit 3500 or so and the uphill 4500.  I suspect I am getting 2 miles to the gallon at 4500 rpm's.?

 

[billandpam]

I have found that with the MH in tow haul all I needed to do was tap the breaks once and the trans would down shift to maintain my set speed.  Even on some long 7% grades in the Rockies.

Bill

 

[billandpam]

I try and keep the RPM below 4500. Just because I don't like to hear the engine screaming, although everyone says the Ford V10 likes RPMs.

Bill

 

[Stephen S.]

I try and keep the RPM below 4500. Just because I don't like to hear the engine screaming, although everyone says the Ford V10 likes RPMs.

Bill

Thing is, with a V10 you have 10 bangs per revolution instead of 8. It sounds like the V10 is turning 25% faster at the same RPM.

 

[araghunathan]

Similar question to KandT and braduah

Hi yall - new to the forum and RV driving. Have a lot paranoia related to mountain driving and brake glazing. We have an 38' Class A RV converted from a school bus. We're about 26000lbs, Cummins ISB5.9 with an Allison 4 speed transmission, air brakes, but no jake or exhaust brakes. We're heading thru AZ later this month and will be driving on I17 to and from Camp Verde up to the Cottonwoods Campgrounds. The Mountain Directory says '6% grade for 7 miles". Do yall have suggestions for safe speeds/gear (2nd or 3rd) to maintain for that length of descent with my rig capabilities and any other strategies for navigating these and future downhills? without actually driving, is there an way to determine the governed RPM speed?

Any advice will be greatly appreciated. Thanks in advance.

-Anand

 

[X-Roughneck Strike 3]

Hello, Fellow Texan and Welcome to the Forum.

It's a old thread, but Lou or Gary and the others will come by to tell you exactly how much of a white knuckle ride you will have before you crash thru that guard rail to your certain death later this month...Only Joking.

I have no clue to the answer with your particular set up. I was looking at School Bus Myself as you can pick them up fairly cheap, and they are built like tanks, I'll bet? When I was looking at them, somebody stated the Insurance might be a bit pricey?

They have to be built far more rugged than these particle board RVs that you do not dare get wet inside. I love my particle board Winnebago Aspect 30J, BTW. Really do.

I took my Gasser V10 thru Scenic Highway 12 from Bryce to Arches. A Delivery Van Truck with extended Frame Rails and a Big old House sitting on it. Was fun. The Sights were amazing on the Drive thru Kanab, and Sunrise Utah @ 9000 Ft. Amazing, and I felt pretty safe while doing it. I used that old Trans to Slow me down. Felt like a 14 year old shifting gears on the steering column.

Too early for popcorn, but I am watching to see what the Gear minded people have to say. I do know that Brakes on RVs and Oil Well draw-works are extremely important.

 

[CharlesinGA]

OP should be using the tow/haul switch on the gearshift lever. Read about it in the manual. In T/H when you step on the brake the transmission downshifts automatically, release the brake and push again, it again downshifts. The owner's manual will fill you in on all of the details on how it works.

Charles

 

[Larry N.]

OP should be using the tow/haul switch on the gearshift lever. Read about it in the manual. In T/H when you step on the brake the transmission downshifts automatically, release the brake and push again, it again downshifts. The owner's manual will fill you in on all of the details on how it works.

Charles

Those don't exist on the diesel that araghunathan has. The original, about a gasser, was from 4 years ago. Without an engine/exhaust brake of some sort, steep descents can be awkward, to say the least. I've never driven a diesel without one, so I can't offer any tips, other than perhaps slow in a low gear might help -- maybe.

 

[Laura & Charles]

Larry is right… do all you can to control downhill speed with your transmission. I rely HEAVILY on my engine brake, but its programmed to work with transmission gear selection (down shifting) which, frankly, the tranny seems to do most in retarding my speed. (Engine brake makes a noticeable difference, just saying I’ve been in situations where engine brake made a noticeable difference, but downshift worked fine.

General rule of thumb: when you peak a steep incline, descend the downhill side using the same gear you needed climbing the peak.

 

[HappyWanderer]

Of all the diesel trucks I drive, only one doesn’t have a Jake Brake. You need to pay close attention to the transmission and tach, just like a gas engine.

 

[unni]

Similar question to KandT and braduah

Hi yall - new to the forum and RV driving. Have a lot paranoia related to mountain driving and brake glazing. We have an 38' Class A RV converted from a school bus. We're about 26000lbs, Cummins ISB5.9 with an Allison 4 speed transmission, air brakes, but no jake or exhaust brakes. We're heading thru AZ later this month and will be driving on I17 to and from Camp Verde up to the Cottonwoods Campgrounds. The Mountain Directory says '6% grade for 7 miles". Do yall have suggestions for safe speeds/gear (2nd or 3rd) to maintain for that length of descent with my rig capabilities and any other strategies for navigating these and future downhills? without actually driving, is there an way to determine the governed RPM speed?

Any advice will be greatly appreciated. Thanks in advance.

-Anand

Cummins 400HP 3000 trans downhill questions

re: your RPM getting high. Cummins says the higher RPM when slowing is not harmful like it is under power. The TCM and ECM "talk" to each other to ensure neither the engine nor Allison are damaged by over-revving. When RPM reach the maximum safe level the Alllison will upshift, regardless of...

www.rvforum.net

Also best driving speed is not to exceed 50 downhill and learning to drive outer to inner lane as you enter the turn when turning left and inner to outer when turning right. Easy done in a car as you have speed to exceed traffic behind you but requires quite a lot of attention to fast traffic behind you as you are slow and BIG. Scares you a first few times but comes naturally afterwards. This is not recommended to general public. But learning to drive like this will add on to your recovery from losing control situations without glazing the brakes. Alternate between brakes usage and lower gears.
In your scenario it may not be needed but good to learn to keep an eye on the engine heat at all times driving downhill. Have a wonderful drive. You will loose your love for 'car' driving after this and may end up using the bus for groccery shoping. Good luck

 

[unni]

Awesome folks of RVforum....

Based on experience, what is the best way to handle hills/mountains when traveling? I'm new to rv'ing and trying to understand the best way to let the engine provide the braking vs 'riding' or 'pumping' the brakes. Below are the Engine/Tran Specs of the unit..

V-10, F-Series Super Duty
320 hp @ 4,750 RPM
460 ft-lbs @ 3,250 RPM
Gas, 6 speed automatic with Overdrive

Any input for this newbie would be much appreciated!

Your engine is a rock. Blindly use tow-mode downhill combined with initial braking to activate it and at times even downshifting manually. Electronically controlled radiator fans in your Rig will take care of the heat to the most part unless you are driving August/September in AZ/TX/CA/NV etc.
Same engine on almost all Cruise America RVs. They last almost 4-5 years and 100000 miles without any issues. Then the resell them in bulk. . Yours being driven by you only should last a really long time.

 

[araghunathan]

Thank you all for your advice. I'm slightly less paranoid, but its still there. What I've gathered from the collective guidance is to downshift, watch the RMS, and take it slow (below 50mph). For clarification - we are a 4 speed Allison automatic transmission; we are a front end diesel as well. There isn't a tow/haul mode on this rig, probably because Bluebird didn't envision it being used as a motor coach, unlike their Wanderlodge discontinued offering.