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Author Topic: Jake Brake and effectiveness  (Read 4485 times)
bobofthenorth
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« Reply #15 on: January 01, 2010, 09:54:51 AM »

I figure if I am ever cited for using Jakes in one of those towns I'll make the appearance and ask the judge if he would rather I had cold brakes or hot ones when his grand-daughter steps off the curb.  The ones that really bug me are the ones with the sign at the top of the hill and the short cycle traffic light right smack dab at the bottom of the hill before you really get into the town.  Not a soul around for miles and they expect me to ride my service brakes down the hill - I don't think so.
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R.J.(Bob) Evans
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luvrbus
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« Reply #16 on: January 01, 2010, 10:07:12 AM »

I see the unmuffled signs about every where I travel now for a while you would see the NO JAKE BRAKE signs but haven't seen those lately.
I was told if you do see one call Jake and they will have it removed and FWIW no engine brakes are not for Jake only the PAC exhaust brake is a load critter also


good luck
« Last Edit: January 01, 2010, 10:10:32 AM by luvrbus » Logged

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Ed Hackenbruch
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« Reply #17 on: January 01, 2010, 10:08:08 AM »

Lin, i just tried to send you an email and a personal mail. Did you get either one?   damn computer!!!!
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1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA
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« Reply #18 on: January 01, 2010, 10:11:05 AM »

Jake brakes turn the engine into an air compressor.  Hence the faster rpm the engine goes, the more horsepower it produces for braking.  On most 4 stroke engines, including the Series 60, 2300 rpm is the maximum recommended engine speed when using Jake brake.  2300rpm also applies to any 92 series (92 series should NEVER be taken above 2300rpm for any reason).  On 71 series, 2500rpm is allowed (unlike 92 series, 71 series many times were turned up to 2800rpm for more horsepower-but, still 2500rpm is the highest recommended).  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #19 on: January 01, 2010, 10:58:35 AM »

In comparing Jakes and Service Brakes, we need to be sure we are comparing apples to apples.

All things being equal, the service brakes will outperform the jakes in the slippery, because they have the grip of all the tires available, and are more closely modulated via the brake pedal.

The jakes get the benefit of only the 4 drive tires and whatever grip they can muster. The sudden action of a downshift during the deceleration can tear them loose.

Too many Transport Canada/NHTSA reports cite the retarder or engine brake as being involved in slippery road collisions.

How do you know that the brakes on your coach are all doing their fair share of the job?

If only one or two of your brakes are doing the work, linings are contaminated, linings are burned and crumbling, the relay valve is failing, wrong valving plumbed in by you or some previous owner, sticking valves, then you'll get slides from those couple of wheels in slippery conditions, and little deceleration.

Trouble is, under "normal" conditions, the little braking you have is enough to stop.

If we put our coaches onto a brake dynometer, I can guarantee many of us will not like the results, having brake positions that show good adjustment but do little gripping inside the drum to stop the coach.


happy coaching!
buswarrior

« Last Edit: January 01, 2010, 11:01:03 AM by buswarrior » Logged

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Eagle Andy
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« Reply #20 on: January 01, 2010, 12:10:45 PM »

All good points on the jakes ,  As someone who drives big heavy stuff everyday and this year in all kinds of road conditions , When Iam driving in wet conditions with temps above freezing I pretty much use my jake at will , That being said iam also awear of whats going on around me . In below freezing conditions Iam a little more cautious . Now when Iam appproching a down grade in winter conditions Iam grabbing grears alot sooner  and I usel my jake as needed , but not for very long I use my brakes alot more in those conditions. I know there are a lot of different thoughts on this Iam only shareing what I do , Its what Iam comfortable with So I guess all Iam saying is we all have are comfort  levels be aware of your conditoins and use your common sence . FWIW
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« Reply #21 on: January 01, 2010, 12:37:36 PM »

Using Allisons for braking is an expensive proposition since it generates so much heat and heat is the #1 enemy of AT.

Jakes don't heat the AT at all and the engine is designed for all this heat, in fact the engine needs a bit of heat when going down grade.

I never ever use an AT for retarding. Even service brakes are cheaper than ATs.

I, too, have experienced that burned service brake smell from another vehicle on the western Tehachapi down grade, sure scared me at first.

For what it's worth, my 4sp 4104 with 671 does a great job of retarding in 4th gear, it all depends on starting from the top at slow speed.
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« Reply #22 on: January 01, 2010, 12:43:57 PM »

I drive a MCI D3, S60, 7 speed manual for the hockey team. Great Jakes by the way. I use them pretty well all the time, except in town or if it is really icy. They really slow me down nicely when taking my foot off the pedal. I pretty well ignore the "no engine brakes" signs, driving downhill into town like is very common in BC. Mine aren't very loud with a good muffler anyway. I am of the same opinion as B.O.T.Norh on this issue. One of the coaching staff on board is a RCMP highway patrol, and he agrees with me. They usually don't bother enforcing those bylaws, as they would not stand up in court, against the safety factor. Really loud ones without a muffler is another matter. How about all the loud pipes on Harleys in the summer? The cops generally ignore that too around here. Although some bikers would argue that it is a safety issue...

Happy New Year to all you nuts by the way,

I don't post much, but I read the board every day,

JC
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JC
Invermere, BC
1977 MC5C, 6V92/HT740
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« Reply #23 on: January 01, 2010, 12:50:19 PM »

Those with proper mufflers have no need to worry about postings against engine brake use.

They are concerned with the ones who make lots of noise, and there are more than enough sound bylaws to deal with them.

Signs are put up by town councils to shut up the rate payers.

But, let's remember the Golden Rule as often as we can:

be courteous in someone else's neighbourhood.

happy coaching!
buswarrior
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RJ
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« Reply #24 on: January 01, 2010, 03:54:53 PM »

All -


We have one of those signs coming into Fresburg SB on SR-41, it says "Truckers - limit engine brake usage".  Interesting wording on a yellow sign.

Now, here's an interesting bit of trivia, at least for here in Californication:

Black & White traffic signs are enforceable by the local gendarmes.

Yellow & Black traffic signs are advisory only, cannot be enforced by the militia.

So law enforcement cannot legally cite you here for using an engine brake based on a yellow advisory sign.

Might research in your locality?

FWIW & HTH. . .

 Wink

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RJ Long
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Lin
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« Reply #25 on: January 01, 2010, 04:31:04 PM »

Here is a link to an article summarizing state regs for Jakes.  It seems that the key words are "indiscriminate use" and "un-muffled".   Notice Kansas seems to be the only state that bans there use for certain vehicles.  One would guess that they feel any use on their terrain is indiscriminate.

http://www.cga.ct.gov/2004/rpt/2004-R-0741.htm

I also found other articles which said that the the State of New York ruled that municipalities do not have the right to legislate about highway braking, and one that said that attorneys for the City of Glendale, Ca advised their city counsel that they did not have the right to pass engine brake laws.  Jacobs is active in opposing such laws claiming that the issue is really modified mufflers and not their product.  They say that highway police should just be enforcing existing muffler and noise laws.

I think that this comes down to a common sense and common courtesy issue.  If you are driving through a residential area, even on a freeway, that has a minimal grade--don't turn them on.  If safety is involved, you must use them.
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Lin
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« Reply #26 on: January 01, 2010, 04:37:30 PM »

Oh, and for your listening enjoyment:

jake brake
(The video's owner prevents external embedding)
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hargreaves
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« Reply #27 on: January 01, 2010, 04:50:03 PM »

A question on jakes and 740 allisons: does the transmission stay in lockup when the jakes are applied? and if so, how is this acclomplished? I would think that if it was in lockup there would be no heat buildup in the trans. I amasking because I am currently converting to an auto.   

Gerry
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now as of Feb 2012 series 50 B400  . Sunshine Coast British Columbia
belfert
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« Reply #28 on: January 01, 2010, 05:53:11 PM »

A question on jakes and 740 allisons: does the transmission stay in lockup when the jakes are applied? and if so, how is this acclomplished? I would think that if it was in lockup there would be no heat buildup in the trans. I amasking because I am currently converting to an auto.   

I believe the other poster is referring to a transmission retarder, not Jake Brakes.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
TomC
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« Reply #29 on: January 01, 2010, 07:42:45 PM »

If you have a normal HT740, it usually locks up in the upper end of 2nd gear and stays locked up all the way to 4th.  When using the Jake brake, the transmission will stay in lockup and down shift at low rpm's till it falls out of torque converter lockup at around 20mph.  You can keep the engine rpm higher by down shifting manually at an earlier time-but don't allow the engine to go above 2400rpm-because the transmission will upshift to protect the engine even if you have it locked in a lower gear selection.  You can also get lockup in 1st by pulling it down into 1st, but many times will drop out of lock up still at around 20mpg.  On the HT740, you can have a solenoid installed that gives you a manual lockup switch on the dash to keep it locked up whenever you want-but then you have to watch that too since you can stall the engine if you don't release it in time.

No matter what your throttle position is on the Allison transmissions, there is always going to be heat to dissipate through the transmission cooler since Allisons produce heat just with the natural dragging of the clutches through the transmission fluid.  About to the tune of 20hp worth of drag more then a manual transmission-and that's directly from Allison.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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