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03-12-2016, 05:19 PM
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#1
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Senior Member
Join Date: Jan 2016
Posts: 540
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Just how DO you use an Engine Brake?
I suppose I could search this forum's database, but I'm sooooo tired of searching for MHs.....I admit I'm feeling lazy (and tired).
OK. You drive up a 6% grade with a 5k lb trailer behind you. You get to the top and it's a 5 mile 6% grade going down. Do you down shift the tranny? Do you get to the speed you want and activate the engine brake? Do you tell the Misses it's her turn to drive? What exactly do you do? An inquiring mind wants to know!!!
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Lovey & Thurston - Cali Foothills
2001 HR Vacationer (SS Minnow) - Gasser!
Obviously A Lowly and Inferior MH
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03-12-2016, 05:20 PM
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#2
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Senior Member
Winnebago Owners Club Ford Super Duty Owner
Join Date: Jul 2012
Location: Where the Rig is Parked
Posts: 1,393
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I just put on the engine brake. It controls the transmission.
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03-12-2016, 05:23 PM
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#3
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Senior Member
Join Date: Jan 2016
Posts: 540
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Wow! That was quick. OK, but when do you turn on the engine brake? Ya see, I have 60-70k miles on gassers, but I can't say it enuff.....I know squat about DPs. I bet I even pull up to the unleaded pumps B4 I realize I'm about to do a bad thing!
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Lovey & Thurston - Cali Foothills
2001 HR Vacationer (SS Minnow) - Gasser!
Obviously A Lowly and Inferior MH
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03-12-2016, 05:46 PM
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#4
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Senior Member
Join Date: Oct 2006
Location: Rochester NY
Posts: 2,706
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My answer is that my engine brake is always on! When you are in cruise, it's smart enough to activate the engine brake to keep you at the set cruise speed + a couple mph.
I know that if you are not using cruise, if your engine brake is 'activated' it will downshift to '2' every time you let up on the petal. If your engine brake is programmed this way, most folks keep it turned 'off' until you need it (more on this topic) as the downshifting seems to be too agressive. In my case, I have mine programmed differently, called 'latch' mode, which I can control via the cruise switch, thus why it's on all the time. I also have mine programmed to downshift into '4' vs. '2' as I find this much less aggressive. I can and do manually downshift it further if necessary.
OK - back to your original question. If you find your engine brake's operation not the way you think it should be, keep it off during most driving. When on cruise control, you can keep it 'on', and if you exceed your set cruise speed by about 3-5mph, it will slow you down going down a hill.
Also, be proactive when going over the crest of a hill and starting down the hill. You should be at the same speed going down the hill as you climbed it, and in the same gear. Engine brake on in these circumstances. And usually the transmission is smart enough to downshift for you. But I recommend manually downshifting before you get going too fast when going the downside of a hill. Remember - going down the hill you should be in the same gear as when you climbed the hill, with the engine brake ON.
Try it a few times and you will get the hang of it.
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Don
'07 Winnebago Journey 34H - CAT C7, Koni's, MCU's, SS Bell Crank, Safe-T-Plus
'07 HHR Toad, SMI AFO, Blue OX
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03-13-2016, 08:30 AM
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#5
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Moderator Emeritus
Join Date: Jan 2000
Location: West Palm Beach, FL. USA
Posts: 27,563
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We just leave the engine brake on 90%+ of the time. I only turn it off when I want to coast a bit, e.g. in stop & go traffic or low rolling hills.
There are a couple different ways exhaust or engine brakes (they are different, though they achieve the same thing) can work, but most of those installed in the last 15 years will automatically downshift as needed for effective braking. Back in the 90's manual activation and downshift was common, but that is largely unnecessary now that engine and transmission share electronic controls that automatically manage it..
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Gary Brinck
Former owner of 2004 American Tradition and several other RVs
Home is West Palm Beach, FL
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03-13-2016, 08:42 AM
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#6
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Registered User
Join Date: Mar 2010
Posts: 8,777
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Quote:
Originally Posted by B Dubya
I suppose I could search this forum's database, but I'm sooooo tired of searching for MHs.....I admit I'm feeling lazy (and tired).
OK. You drive up a 6% grade with a 5k lb trailer behind you. You get to the top and it's a 5 mile 6% grade going down. Do you down shift the tranny? Do you get to the speed you want and activate the engine brake? Do you tell the Misses it's her turn to drive? What exactly do you do? An inquiring mind wants to know!!!
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B Dubya
Exhaust Brakes - How Engine Brakes Work | HowStuffWorks
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03-13-2016, 08:43 AM
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#7
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Senior Member
Monaco Owners Club
Join Date: May 2012
Location: DFW, Tex-US
Posts: 6,196
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I too am in the leave it on camp....
the extra braking has saved my bacon a couple of times already in emergency stops towing the toad
AND since it uses the engine backpressure to stop, it's saving that expensive brake job for much later
heck, even when I had the large deezle trucks towing my 5'ers I would use the engine braking and neither one of my trucks ever needed a brake job before I traded them in !
__________________
'11 Monaco Diplomat 43DFT RR10R pushed by a '14 Jeep Wrangler JKU. History.. 5'ers: 13 Redwood 38gk(junk!), 11 MVP Destiny, Open Range TT, Winn LeSharo, C's, popups, vans, tents...
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03-13-2016, 10:47 AM
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#8
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Registered User
Join Date: Mar 2010
Posts: 8,777
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Quote:
Originally Posted by JohnBoyToo
I too am in the leave it on camp....
the extra braking has saved my bacon a couple of times already in emergency stops towing the toad
AND since it uses the engine backpressure to stop, it's saving that expensive brake job for much later
heck, even when I had the large deezle trucks towing my 5'ers I would use the engine braking and neither one of my trucks ever needed a brake job before I traded them in !
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JohnBoyToo
Although I only use the Pacbrake when it's needed the disc brake pads on my coach lasted 144,000 miles).
Mel
'96 Safari, 146k miles, (mine since '01)
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03-13-2016, 10:54 AM
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#9
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Senior Member
Country Coach Owners Club Solo Rvers Club iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 37,725
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Mine's on most of the time. Then I select Low, Medium or High. High is pretty much useless for most highway grades though.
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2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft, HWH Active Air
Charter Good Sam Lifetime Member, FMCA,
RV'ing since 1957, NRA Benefactor Life, towing '21 Jeep JLU Rubicon Ecodiesel
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03-13-2016, 11:28 AM
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#10
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Registered User
Join Date: Mar 2010
Posts: 8,777
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Quote:
Originally Posted by Mr_D
Mine's on most of the time. Then I select Low, Medium or High. High is pretty much useless for most highway grades though.
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Mr_D
Do you have an exhust brake?
Or a compression release engine brake?
(I thought only compression release engine brakes had variable settings).
Mel
'96 Safari, with an exhaust brake, (by Pacbrake)
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03-13-2016, 07:44 PM
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#11
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Senior Member
Join Date: Nov 2011
Posts: 884
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Just how DO you use an Engine Brake?
I leave the Jake Brake on 99% of the time. However, I had Allison reprogram the transmission so it does NOT automatically shift down to the next lower gear. Mine will stay in whatever gear I'm in at the moment. Our coach has the Cummins ISL with the 2-stage compression brake. Even in the LOW position, the braking effort provided with the original Freightliner programming was just too aggressive.
Freightliner programs them from the factory so the transmission will down shift to the next lower gear as soon as possible without over-revving the engine in that next lower gear. In other words, the Jake is programmed to deliver 100% of its braking effort 100% of the time. That makes the Jake brake useless when you want less than 100% braking effort. Freightliner takes the position that the typical motor home driver is not smart enough to know how to use an engine brake properly, so they dumb it down by programming it to deliver 100% braking on every stop.
But what about just slowing down for an interstate off ramp? Or driving on surface streets in stop and go traffic? Or going down a gentle grade? In all of those situations the use of a Jake brake is helpful, but not at 100% braking effort. With mine programmed to stay in the same gear, I can enjoy gentle braking effort on every stop. If I need more engine braking than what the current gear provides, a couple button pushes on the Allison transmission control and I've got more.
The transmission still downshifts by itself as I slow down, but it does so at 1,000 RPM in each gear down through 2nd, where it drops out at the 1,000 RPM point, which occurs at 15 mph. The Jake provides gentle braking effort all the way down to 15 mph on every stop.
This programming change took less than 30 minutes at an Allison shop and cost $50. Absolutely the best improvement in drivability I have made to this coach.
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03-13-2016, 08:21 PM
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#12
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Senior Member
Join Date: Jan 2016
Posts: 540
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^^^^^ While I thank you for that detailed explanation, for now I'll just file it in my DP folder for future reference, as this is way beyond my pay grade.
__________________
Lovey & Thurston - Cali Foothills
2001 HR Vacationer (SS Minnow) - Gasser!
Obviously A Lowly and Inferior MH
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03-13-2016, 08:26 PM
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#13
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Senior Member
Country Coach Owners Club
Join Date: Dec 2010
Posts: 7,754
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Rule of thumb is that you go down the hill in the same gear you came up the hill.
I leave my exhaust brake on all the time. Main reason is I don't want to fool with looking for the switch
__________________
Don
2002 Country Coach Intrigue
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03-13-2016, 09:10 PM
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#14
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Senior Member
Monaco Owners Club
Join Date: Jul 2011
Location: B.C.
Posts: 4,638
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The safest way to use your exhaust brake is to slow right down at the top of the hill and shift down to the gear you pulled the hill in. Engage your exhaust brake and see if it is holding your speed back without braking. If it is holding back too much you can up shift and reach a gear that it will hold you back without having to use too much foot brake. It is much easier and safer to gain speed slowly than to try an slow it back down.
Gaining too much speed at the top of the hill can heat up your brakes very quickly trying to get to the point where the exhaust brake will do the lions share of the work.
Once you have tried this a couple of times you will get the feel for the right gea, and how it holds back.
__________________
Dennis & Marcie & Captain Hook The Jack Russell,aka PUP, 2006 Itasca 29R 2017 Equinox toad. RVM59
We came, we went, nothing broken, nothing bent!
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