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Topic: Help with info re: Retarder (Read 1128 times) previous topic - next topic

Help with info re: Retarder

I am posting this for Kent Speers, who is presently on the road driving his new(to him) 1993 U300SE 40' coach back home after purchasing it in Denver.  It has a 6V92 Detroit  350HP engine w/ retarder and (he thinks) a Jake brake as well.  Allison 746 trans.  There is a 3 position switch for the Retarder, Off ... On 1 ... On 2.  There is a switch on the`dash marked "Override" that is original to the`coach.  Also,  a`switch marked "Aux Pump".    Kent has gone through the manuals briefly, but has not seen a reference to these switches.  Can anyone shed light on the Retarder switch, when the Jake is activated, and what the others refer to?  Kent has been playing with them, but doesn't feel any great differences in performance.  He is presently in Kansas ... on the way to Kansas City ... Help??
Carol & Jeff Savournin
Usta have a '93 U225 36', Usta have a '95 U320 40', Usta have a '02 U320 40'
Usta have a 2006 Born Free, Usta have a 2011 Phoenix Cruiser
Usta have a 2012 Jeep Wrangler Unlimited 4dr
"Your time is limited, so don't waste it living someone else's life."  Steve Jobs

Re: Help with info re: Retarder

Reply #1 –
My best guess at this is that I do not think his coach has a "retarder" as in "transmission retarder". The switch for the jake brake is generally marked "RETARDER" which may give the impression that there is a transmission retarder.The jake brakes can have 3 position switches, OFF, 1, 2. Where, in position 1 the jake is active on 1/2 of the engine cylinders for lighter braking and when in position 2 all of the cylinders are active and give maximum engine braking. Not sure about how the jake brake works on the Detroit engine.
Rick

Re: Help with info re: Retarder

Reply #2 –
One more thing, if he feels no difference when he throws the switch then there is something wrong with the system. On my coach, when the switch is thrown, the transmission will downshift to 4th (if RPMs allow it) and the jake brake will activate. My jake has only one position so it goes to maximum braking. Make sure the cruise control is off or you will have to step firmly on the brakes to activate the jake brake.
Rick

Re: Help with info re: Retarder

Reply #3 –
Quote
On 9/16/2010 3:26 PM, Rick wrote: 
One more thing, if he feels no difference when he throws the switch then there is something wrong with the system. On my coach, when the switch is thrown, the transmission will downshift to 4th (if RPMs allow it) and the jake brake will activate. My jake has only one position so it goes to maximum braking. Make sure the cruise control is off or you will have to step firmly on the brakes to activate the jake brake.
 
Rick 1995 U-300SE 40'
CAT 3176B
I will add that I believe he only has the JAKE as his retarder. It is likely a 2 speed jake.
 
Any DDA shop (Detroit Diesel Allison) can explain the trans and jake interaction for his coach.
 
My 95 U320 M11 Jake is wired the same as Rick's 3176 CAT - one speed.
Does the job...
 
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Help with info re: Retarder

Reply #4 –
I also thought the Jake was inop on my HT746/6V92. Went to Allison Rep in Dallas. Went for a ride, It does very little in 4th, but really works good in 3rd and 2nd going down a hill.
I used today coming down Pipestone going into Butte MT. Going up I was in 2nd doing 40 MPH, RPM about 1400-1500. Coming down I needed to shift in to 3rd or I would have come down @ 25 to 30 MPH.
My switch is three position, Off (no red light ) next is partial Jake, all the way is full. After off the red light in switch stays on
No need to apply service brake after turn it on if you turn it on before you get off the throttle.
I have used it with the cruise control on. If the engine (cruise control) call for throttle to bring it up to set speed it also disengages the Jake. when the throttle backs all the way off ( to hold speed) the Jake comes on (if armed).

I would really love to have the transmission retarder, But as an upgrade @ this time is $8000 to $9000. It was a $10000 option in '93

bill
1993 U300, 6v92
build 4366
USAF retired, Flight Engineer, C124, C130
 ATP, A & E.  & ex AI

Re: Help with info re: Retarder

Reply #5 –
The Override switch allows you to keep the engine running when shutdown engine light comes on. without that the engine quites on 1 minute.

Hope you like the SE as much a I like the '93 U300
1993 U300, 6v92
build 4366
USAF retired, Flight Engineer, C124, C130
 ATP, A & E.  & ex AI

Re: Help with info re: Retarder

Reply #6 –
It is very simple to figure if you have the transmission retarder or the Jake brake.
Simple apply it/brakes so you can feel the effect, then while braking,  listen, if you hear it in the exhaust it is the JAKE BRAKE, if silent it  surely is the transmission retarder.
FWIW
Dave

Re: Help with info re: Retarder

Reply #7 –
Thanks to everyone for all the help. I think I finally figured things out. It does have a two speed Jake brake I've learned that from the information given by the other members. With my window open I can hear the Jake brake and I can feel its action.

I finally found the section pertaining to those three switches in my manual. Someone had moved it clear to the back under the HWH tab.Once again thanks to all, especially you Carol.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: Help with info re: Retarder

Reply #8 –
Quote
RE Dave:
It is very simple to figure if you have the transmission retarder or the
Jake brake.
------
If someone wants to know if they have an Allison transmission Retarder, look at the end of the transmission where the drive shaft connects. Retarders have a separate (retarder) unit about 4" deep that is bolted to the end of the Allison transmission.  Without a retarder the transmission is shorter and drive shaft longer.
 
Retarder transmissions also have an external cylinder accumulator that is often on the curb side of the transmission.  This is the part that was at risk of falling off on ISM engines. Accumulator has a single large diameter hose connected to the retarder end of the transmission.  When retarder is first activated a piston in the accumulator instantly loads the retarder section with a quantity of transmission fluid to get retarding started without a longer delay.

Re: Help with info re: Retarder

Reply #9 –
If you haven't found out yet. The aux Pump sw is for winter operation. The heat lose for the coolant was pretty severe in the 40' coach.
an Aux Pump in the coolant line pressues it to the front heat exchanger.
1993 U300, 6v92
build 4366
USAF retired, Flight Engineer, C124, C130
 ATP, A & E.  & ex AI

Re: Help with info re: Retarder

Reply #10 –
Jake brake on U300 Detroit Diesel:

Yes, switch has 3 positions, off, first position activates Jake on the exhaust valves on the right side of the engine, second position (all the way down) works on both sides. If you are heading downhill at 70-80 mph in fourth, it will provide fairly good breaking action on VERY MILD grades. On steeper grades you will want to be in a LOWER gear and the Jake really shines here especially at higher rpm. I don't let the rpm go above 2000 (on a Detroit) before I apply the service brakes, let the rpm drop to 1700 or so and then let the Jake do the work again repeating the above sequence. I have been down 12% grades with only moderate use of the service brakes (you can't smell them at the bottom) and not held up traffic much. When you lightly touch the throttle as the road may flatten a bit, don't need the braking action, the Jake brake switches off automatically but will activate again when you lift off the throttle. Nice! On a couple of REALLY steep, twisty roads, I have pulled off the road and stopped, punched the Jake switch , selected first gear and started down without ever using the service brakes. No anxiety this way wondering if it shifted down to first.
If the road may be slick as in the first rain for a while, I think about it before hitting the switch. Same with suspected black ice early in the morning. SLOW DOWN anyway in the rain. 30,000 lbs. is a lot of weight. I don't use the Jake in the snow! Lots of weight in the back and if the back end comes loose in the snow (or the rain) heading downhill, you will NEVER catch it, especially with a toad trying to push you around. Unless you absolutely have to drive, pull off and turn on the TV if it's snowing.

You can keep out of most trouble by heading down the other side of the hill in the same gear as you went up the hill. If you went up in third, manually punch in third on the transmission selector before you start down.

A Jake Brake or transmission retarder is not designed to overcome any malfunction, wear or other problem your service brakes may have! If your brakes don't seem 100%, get it checked out and if you think your air parking brake will ever help in any emergency, it won't.

Best driving to everyone,

Pierce & Gaylie Stewart
93' U300/36

Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Help with info re: Retarder

Reply #11 –
Pierce, Good wording, I just would like to mention on the DDA engines, the higher the RPM the more effective the Jake Brake becomes, and taking the engine up to 2300 RPM is not going any harm at all and makes the Jake much more effective.
As for RPM, we routinely turn the 71 or 92 series 2300 to 2600 RPM with no ill effects, the key is not to keep them above 2600 RPM very long.  Have turned one at 3600 RPM and had no ill effects, but that was for non highway playing with crazy turbos, and injectors, a real fun/expensive learning experience.
One small point, when and if you need work done on the engine, make sure it is done by a DDA mechanic as a lot of good meaning non DDA mechanics are clueless to the proper injector, valve adjustment and sequence, then wind up with a rod thru the block due to wrong timing, injector setting, sad to say but seen that more than once.
Enjoy the 6V-92 and only use the 40 Weight oil, not 15W-40.
FWIW
Dave

Re: Help with info re: Retarder

Reply #12 –
Glad my two sources of Foretravel and 6V92 got together.
Pierce and Dave always have good info.
1993 U300, 6v92
build 4366
USAF retired, Flight Engineer, C124, C130
 ATP, A & E.  & ex AI

Re: Help with info re: Retarder

Reply #13 –
I sure am glad to have this help. The one remaining question is the coolant. Does this engine take standard antifreeze without additives or does it require something like SCA with special anitfreeze.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback