| Author | Message | ||
| Roger Baughman (Roger)
Registered Member Username: Roger Post Number: 30 Registered: 11-2006 Posted From: 69.232.66.128  Rating: N/A |
I suspect that someone will know the answer to this question. After using my Jake brakes I sometimes forget and leave the brake on and then step on the fuel pedel to go faster. I will realize the Jake Brake is on and turn it off. Is this harmful to the engine or the Jake Brakes? Thanks for your help guys, Roger | ||
| Dan West (Utahclaimjumper)
Registered Member Username: Utahclaimjumper Post Number: 105 Registered: 1-2005 Posted From: 208.66.38.115 Rating: |
If you dont have a throttle pedal lock-out than you can bend valves, not good, a simple throttle pedal micro switch will prevent this from happining | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 205 Registered: 10-2003 Posted From: 74.244.14.221  Rating: N/A |
On my 6-71 it is just a microswitch that is activated by a rod in place of the buffer screw on the govenor. When you push the go pedal the govenor comands fuel and disengauges the jake all at once. Unless I am missing something I don't see how you could bend a valve with this type of set up | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1205 Registered: 10-2003 Posted From: 71.58.110.9  Rating: |
What is going to bend the valves? The pistons don't get any closer to the valves whether the Jakes are on or off. | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 192 Registered: 3-2006 Posted From: 166.90.247.59 Rating: N/A |
Roger In order for the Jake brake to work you have a switch in the tranny that only allows the Jake to work if the tranny is in lockup and another switch on the govenor that completes the circut when the throttle is closed to turn the Jakes on. If either switch is opened the Jakes disengage. I leave my Jakes on all the time so they are there when I need them. Hope you can understand this. Bill | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 565 Registered: 8-2006 Posted From: 207.231.75.253 Rating: |
Well, With the exception of the first reply, everyone is right. Lets think about this a second or two. Jakes operate by opening the exhaust valve(s) at the top of the compression stroke, on a signal from the fuel injection cam, (or the DDEC) under certain conditions. Those are the Jake buffer switch feeling the rack in the no fuel position, (because the engine is being turned by the driveline faster than the throttle position,) and the trans and or clutch switches closed, (trans. in forward, no foot on clutch.) As the Jakes open the exhaust valves at the top of the stroke anyhow, throttle position can't move the pistons any closer to the head.... A buffer switch out of adjustment will cause black smoke when the jake is on, as some fuel is being injected, then immediately thrown out when the exhaust valve opens at the top of the stroke, releasing all the compression. A direct answer to the original question is NO, to both parts. As Bill says, many people leave the switch on all the time. Jakes make for a much faster double-clutch! HTH, George | ||
| Stephen Fessenden (Sffess)
Registered Member Username: Sffess Post Number: 743 Registered: 1-2002 Posted From: 66.38.120.219 Rating: N/A |
There is a jumper that is put on the throttle switch for adjutsting something. That was left on mine and I had what you describe. A mechanic pulled the jumper and it functioned normally, turning off the jake when the throttle was depressed. The only time I turn the Jake off is when I want to coast a bit on level ground and when I want to be polite in congested areas. Otherwise it stays on most of the time. The trucker that owned this bus before me showed me an emergency stop with full brakes, full Jakes and downshifting the Allison automatic. It makes a difference. | ||
| Roger Baughman (Roger)
Registered Member Username: Roger Post Number: 31 Registered: 11-2006 Posted From: 75.18.113.191 Rating: N/A |
Thanks guys for the infomation on the Jake Brakes, Roger | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 838 Registered: 12-2000 Posted From: 174.144.209.97  Rating: N/A |
Running with the Jakes on all the time can reduce mileage slightly because every time you lift off the throttle the Jake slows you more than just coasting would. Takes more fuel to get back to original speed. Lifting off the throttle to just above idle prevents the Jakes from coming on. Jack (Message edited by JackConrad on October 02, 2008) | ||
| Roger Baughman (Roger)
Registered Member Username: Roger Post Number: 32 Registered: 11-2006 Posted From: 75.18.113.191 Rating: N/A |
Thanks Jack, very helpful. Roger | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 348 Registered: 7-2006 Posted From: 75.210.128.19 Rating: N/A |
Jack....not sure I totally understand your last sentence. When I flip the switch, the Jake is either on....or off. I just re-read the entire thread and realize that perhaps my Jakes are a bit "different" somehow. I can leave them on or not, everything is hunky dory BUT....when I get close to idle speed, for instance at a stop sign, the engine will kill if they are on. I mentioned this in a thread several years ago but didn't seem to get any definitive information. Maybe just didn't read close enuf. : )  George...one clue that something may be amiss is that indeed I do get black smoke when they are first switched on. RCB (Message edited by chuckllb on October 02, 2008) | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1227 Registered: 5-2001 Posted From: 65.74.65.209 Rating: |
The buffer switch, if it is adjusted and working right, will prevent the engine from dying when your foot is off the throttle. The rack goes to no injection when slowing down and it presses against the buffer switch, which turns the Jakes on. When idling, the rack is far enough away from the no fuel position that the Jakes will not come on. When we got our coach, it had Jakes, but there was no buffer switch. Ours acted like yours does until we got the switch installed. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| JC Alacoque (Jc_alacoque)
Registered Member Username: Jc_alacoque Post Number: 75 Registered: 7-2006 Posted From: 72.45.68.242 Rating: N/A |
RCB, maybe you don't have a buffer switch or it is defective. I know a bus with a foot switch. You turn the Jakes circuit on with a switch on the dash, then when you need them on, you press the floor switch with your left foot. When you need to use the clutch, of course the Jakes come off. Quite a simple system, and much cheaper than a buffer switch at $180.00. JC | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 571 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
RC, Tom just got my vote, as his explanation is exactly correct! To the black smoke issue, the buffer switch adjustment is the culprit again, as it is allowing the Jakes to operate while the governor is asking for some fuel. It is also possible that you have Steve's problem above, (a jumped out buffer) so look and see if you have one, and that it has one wire on each of two terminals. Its in the vee, low on the front of the gov housing. If you have fast idle, there is a concentric shaft with an air cylinder right there with it. There is a good explanation on setting the buffer in the archives. HTH, George | ||
| Mike Eades (Mike4905)
Registered Member Username: Mike4905 Post Number: 172 Registered: 12-2000 Posted From: 68.200.183.92 Rating: N/A |
I broke a valve train rocker arm and luke told me it was caused from leaving my jake on all the time. It might have been because I was overloaded. I don't know. I now run with the jake off unless I need it for a major hill. On th enew buses I drive the jake is on all the time as per the manufacturer. | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 349 Registered: 7-2006 Posted From: 75.211.196.233 Rating: N/A |
Interesting...thanx, folks. Incidentally, I have a Cummins 220 turbo,pancake style. Any difference here? One hears very little about Cummins on this board.... as it has been for the 7 years or so I have been participating. Thanx again. RCB | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 299 Registered: 3-2007 Posted From: 71.55.193.233 Rating: N/A |
RC: We are DETROIT IDIOTS over here and who makes cummins? Honda? Just kidding again of course. I still love my ole DD. I know some had cats and hated them and either pulled a swap or traded for another dd. I have a friend that has an Eagle with series 60 and auto that a run he used to make with 8v-71 at 45 mph he can run at 65 up the grade . LONG LIVE DD's gomer | ||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 72 Registered: 7-2006 Posted From: 205.250.179.187 Rating: N/A |
mike there are very few good dd meck. that know how to put a jake on properly. south Or. deisel had one , Ted at Wiiiams Cal,Jim in Victoria, Mike in Nanaino and Wayne at Camprell River and that is the list of guys that can touch the jake on my bus. and yes there are other good meck. out there and they will tell you that they want nothing to do with a jake on a DD. they have all told me the same thing that if a DD blows up and it has a jake on it they will say oh it was the jake but when asked why the they get red in the face and admitt it was not set up right or was not wired in proper, Not the fault of the jake product, just poor installation or set up, so if you go to a shop and the guy goes for a book to see how it should be done, try another shop however even the best of them will get out the book and Verifie that he did it right. before anyone works on your jake ask them how many that he has installed and be sure that he has the right tools for the job. have it done right and enjoy the ride. | ||
| Douglas Tappan (Dougthebonifiedbusnut)
Registered Member Username: Dougthebonifiedbusnut Post Number: 65 Registered: 10-2004 Posted From: 75.69.223.64  Rating: N/A |
Hey RC, I have an 855 Cummins in my crown as you know I have a hard time dissagreeing with Luke but unless the electical end of the engine brake was incorrect I can't see how leving the jakes would break a rocker. AS for your Cummins I've been driving big trucks most of my working life and if the electical side of the jake is correct you dont ever need to turn your jake off. Having said that beware! There are times when you don't want your jake on like if your in a snow environment or wet one.Some jakes are better than others. Cat and Cummins brakes will stop the wheels from turning in slippery conditions. I have little experiance with DD's so can't comment. | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 489 Registered: 10-2006 Posted From: 208.100.193.239 Rating: |
Since I'm in the process of getting a bus with both Jake's and a retarder, my concept is rather simple. Wire the Jake into a of/on switch and the brake light circuit , so ONLY when breaking is started the Jake will come on. The retarder also will be on a switch , for in town or hills that are bigger than Old Jake can handle. Any reason not to take this approach? FF | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 146 Registered: 1-2007 Posted From: 208.81.157.90  Rating: N/A |
FF, I would want to use the jakes without 'riding' the brakes. Long downhill grades come to mind. If you use cruise control there is potential for hitting the jakes with throttle applied unless they are wired through a buffer switch too. A foot switch is a simple way to go. Don 4107 | ||
| JC Alacoque (Jc_alacoque)
Registered Member Username: Jc_alacoque Post Number: 76 Registered: 7-2006 Posted From: 72.45.68.242 Rating: N/A |
FF, the nice feature about Jakes is that they come on and slow you down before you have to apply the service brakes. That keeps them cool for when you really need them. If you want to keep it simple, use a foot switch like Don 4107 sugests, and see my post above Oct 02. JC | ||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 76 Registered: 7-2006 Posted From: 64.180.195.198 Rating: N/A |
the best thing to do is go to your local DD dealer amd ask for a copy of the Jake brake wiring, it will show that you can have either a simple on off switch or the 2 position switch that has the high low feature, this means that when in the high position all cyl. are effected by the jake, when in the low position only half of the cly are used, this is a good feature as you can sneak through towns without it waking up everyone within 2 miles. as you will see from the diagram they will give you that you wire from the ignition switch to the jake switch to a micro switch that is operated by the clutch pedal, this means that when you do not have your foot on the clutch it allows power to the buffer switch on the gov. now when you put your foot on the clutch pedal it opens the circuit and shuts of all of the jake masters which are located under the engine covers that cover the rocker arms. the masters control the slaves. as the buffer switch is how part of the gov fuel control if you attempt to apply fuel it will cut out the Jake, this feature allows you to shift gears without worrying about the Jake being on. if there is a better way to wire in a Jake i am sure that the people at the Jake would know about it and their way has worked for a lot of people over the years. | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 492 Registered: 10-2006 Posted From: 208.100.193.8 Rating: N/A |
There are lots of times I wish to simply coast , not break , but not be on the throttle . How does the Jake handle that? Turn off the switch every time? A tiny amount of brake air will light the tail lights , no actual breaking is done , so the foundation breaks wouldn't actually be on. FF | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1211 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
You can study or download this info free at the Jacobs engine brake site. | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 147 Registered: 1-2007 Posted From: 208.81.157.90 Rating: N/A |
Fred, You really want to have the Jake switch in a handy spot. You also want to consider having the option of partial Jakes. I forget what engine you 'new' bus has, but if you can split the Jakes into each bank (V-eight) or group of cylinders (inline) it is more likely that you can have the right amount of Jake brake for any grade or situation. Many times going down grade all it takes is alternating between partial and full Jakes to maintain the desired speed envelope. Many trucks have 3 position Jakes: Two, four, or six cylinders. Very handy. If you wire them up to work only with the brake treadle you will still be turning them on and off. Good luck Don 4107 | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 350 Registered: 7-2006 Posted From: 75.211.201.180 Rating: N/A |
Interesting statement, Don....but can't see how it is more beneficial than simply "learning" how to use "full" Jakes....Kinda like learning to shift..or brake...or steer...etc. In the past seven years, I have learned a lot of respect for handling a coach,,,,under a variety of circumstances. Nothing like experience. FWIW RCB | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 148 Registered: 1-2007 Posted From: 208.81.157.90 Rating: N/A |
Nothing wrong with using full Jakes or no Jakes. Just handy to choose the amount you need to do the job. How can I win the 'who has the most switches on the dash contest' if I don't take every opportunity to add another toy. Kinda like having a porta-potty and a sleeping bag for an interior. Gets the job done. Sometimes more toys are fun and useful too. Thats why we have buses, to do it the way we think it should be done. Have driven without Jakes, have driven with single level Jakes, have driven with multi level Jakes. Since I have to install Jakes in our new bus, you can bet the option of one bank or both is going in too. Do I need Jakes? Nope. Do I want Jakes? Yep. Just like I don't 'need' power steering but it sure is nice. Doing it my way and hope you are doing it yours, Don 4107 | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 578 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
I would like Fred to explain how an air operated brake light switch can light the BRAKE lights, while the air operated cylinders don't apply the brakes? | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1366 Registered: 12-2000 Posted From: 76.68.120.122  Rating: N/A |
Hello Fred. If I have read your post completely, you are looking to use the jakes in an automatic/blended fashion in conjunction with the brakes, and the retarder will be used stand alone as you desire? Sounds good to me. You do want to be careful with a long "cracking" type brake application, as you describe for getting the jake circuit to power up, the front shoes will be ever so lightly against the drums, the rears maybe, maybe not, depending on the relay valve's sensitivity. If they touch, they will be making heat, and potentially lots of it over an extended descent. I'd wire it as you describe, and have a double throw switch to change to a manual control, if so desired. Best of both worlds, auto and manual! branch idea thinking: What I have never understood is why the jake switch is always some place you have to reach for it.... I'd prefer the control to be on the shifter, since gear use is usually part of the exercise.... happy coaching! buswarrior | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 320 Registered: 2-2001 Posted From: 69.77.156.190 Rating: N/A |
If you want partial or full Jakes, the switch you want is double throw with center off position. On our Eagle it is located on the switch panel on the left under the driver's window. It's no trouble to have it there. I have partial or full choice and I like it. You can always use the switch on full but sometimes that's more braking than is required. The half position is handy. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 579 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Just as BW says, wiring the Jakes thru the brake light switch will cause cracking. My brake light switch is factory plumbed in the rear brake cylinder circuit, not the pilot circuit from the treadle to the relay valve. So, that means that all of the brakes would have to be on to get any Jakes. Its an idea, but IMNSHO, not a good one. Same feeling about a button on the floor, who wants to go down a long hill with their foot stuck on a button? Not to mention that everyone else will be stepping on it trying to dim the lights. Mine has a factory air horn button on the left floor also. Suggestion is definitely a switch where it is real convenient, and a double throw switch, reasonably convenient, with the rest of the switches for two speed? Now, I have a question: Jakes AND a retarder on the same driveshaft, trans, and universals? George | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 351 Registered: 7-2006 Posted From: 75.209.220.186 Rating: N/A |
...eh what? ( I'm with you George....I think... ) RCB | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 580 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Good Morning RC, "I think, therefore I am." (Somebody said that.) I think you got my drift! (I said that.) Lets see if this causes the same consternation with at least a few others! Regards, GMT | ||
| John Lacey (Junkman42)
Registered Member Username: Junkman42 Post Number: 56 Registered: 3-2007 Posted From: 66.82.162.14  Rating: N/A |
George, You made a interesting observation! My MC7 has jakes and a retarder and was so equipped from the factory! I beleive that My jakes are only on one bank but am not sure of this. I have the original books and paper work for this coach as it ws bought and converted brand new as a motor home! Perhaps the reason I have only one bank is because of the issue You mention? I also have the air horn switch on the side which is difficult to reach for My short legs. Maybe only the shadow knows? John | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 841 Registered: 12-2000 Posted From: 99.204.25.166 Rating: N/A |
This is just "our way". When we started buying Jake Brake parts on Ebay, we decided to use a different approach to control the Jake Brake. We installed 2 pressure switches in series to control the Jakes, in addition to the dash mounted switch. Using a pressure gauge, I found that it takes 5 PSI at the air throttle actuator to open the throttle, so I installed a 3 PSI NC switch in the air line at the throttle actuator. This disconnects the Jakes just before the throttle opens. We were also concerned with the Jake staying on when the trasmission torque converter comes out of lock-up. To prevent this, I checked the Allison manual and found that the lock-up pressure is within 15 PSI of main line pressure (which is 175 PSI). There is a lock-up pressure test port on the transmission, so I installed a 60 PSI NO switch in this port. As soon as The lock-up pressure drops the Jakes shut off. Although we have not yet installed the actual Jake brakes on our engine, we have all the wiring completed and a "Jake Brake ON" LED on the dash to confirm proper activation of our Jake Brakes. Jake Brake dash mounted switch is on the left of drivers seat and easily accessed. When coasting, barely touching throttle disconnects the Jake circuit. Just our way, YMMV Jack | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 581 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Jack, An interesting thought, and it would be one of a kind! If you are planning on using the buffer switch in series with your other two switches, it would be a "belt and suspenders" approach, which would work well. Years down the line, when you never had a torque conv failure, you might not even remeber what you did to prevent it. Decelerating converter lockup drops out halfway thru second gear, which would be a good point to drop out the Jakes. One question though. What happens if the throttle pressure switch goes out of calibration by only a couple of pounds, or gets sticky? With a buffer switch, you wouldn't even know it, without one, you would have throttle and Jakes. The solution would be a micro switch on the throttle actuator/governor linkage instead of the air pressure switch. FWIW, George | ||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 81 Registered: 7-2006 Posted From: 154.5.113.166 Rating: |
when you talk about having the jake wired through the tail light switch, did you take into consideration that the main reason that you are putting jakes on is to keep the brake drums cool and allow you to use your brakes when needed. remember that braking causes heat build up in the shoes and drums and the more heat they retain the less braking power you have. how if you have the brakes being applied even slightly when trying to get the jake to come on you better know if there is any heat buildup on these parts and if so you are worse of the you were with no jake as when you go to apply the brake there is already heat in them, not good. there are too many things that have to work perfect on paper never mind on the bus for that to work . just remember that with this type of setup that when you are coming down a down grade and you are trying to feather the jake with tail lite switch and those drums are hot and you have to apply your air brakes to stop or slow down you may already have too much heat in them and by appling the air to them they will not have the power to act as you want and could cook the brakes before you get slowed down or stopped. beleive me it is not a nice feeling having cooked brakes and alot of down grade still in front of you.no after all these years that the jake company has worked on their system this bumb old guy will go with what they found best and it sure has worked for me and alot of other people. but as FF says do it your way it is your bus........... | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 352 Registered: 7-2006 Posted From: 70.210.162.152 Rating: N/A |
Interesting points, Mel.....seems to me if it would work out better some other way, the Jacobs people would have used it. We have learned to use the Jakes thru trial ( and not too much error... ) Brakes are seldom used in our western mountainous areas and if one pays attention to RJL's advice (driving way ahead of yourself) our Jakes also are used to lessen the use of the brake system. George...you and Jack have lost me almost entirely....I think But I'm workin' on it. I am certainly not opposed to new ways and new ideas, but tried and proven is worth a bunch to me personally. Too much "stuff" just adds to the possibilities in any given situation. KISS theory works for me, as has been said several times on this ( and many other) thread,...do it your way...and enjoy the trip! By the way, Mel...if you could break up your posts a bit (paragraphs) it would help the rest of us old guys read through it. FWIW Thanx. RCB | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 582 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Afternoon again RC, You and John got what I was wondering about real quick, without me even saying it, and that was the idea! I didn't want to bias the opinions at the start. Nobody said we were goofy (I didn't say nuts) either, so things are good!! On to the second point, controlling the Jakes with a pressure switch on an air throttle, and another on the converter lockup pressure line would work. That way, the Jakes would only operate when the throttle was closed, and the converter was locked up, which is more or less halfway thru second gear, all the way up to high, whether it is 4th or 5th. We are assuming there is an on and off switch in the circuit also, for when you want to coast, or don't want to make noise. This wouldn't affect two speed operation either. This way, the trans is playing buffer. NOW, YOUR THIRD AND FOURTH PARAGRAPHS ARE: the cat's meow, nirvana, the holy grail, or some other complimentary term, take your choice!!!!! There is nothing more to say, the simplest configuration that will do the job is the best. In my opinion, that's a buffer switch, it can't fail and leak trans fluid at 175psi either. Being kind of against Jack's idea IS being picky, and I'll admit it, here and now, and I almost didn't say anything, but this is a discussion of all the possibilities. Unique in a bus is okay as long as you are there to work on it, or explain, otherwise not so good, as nobody but you knows how it was done. Now, I have to rat on myself again, because I missed a part of Jim's post, and didn't see it for a day, this is a little picky too, but. Just a double throw switch (SPDT)won't work for two speed Jake. It will have to be double pole-double throw, (DPDT) with two jumpers, or one end of a big diode will have to be wired to the full position terminal of a SPDT switch, along with one bank, then the other end of the diode to the half position terminal, with the other bank. Needless to say, wire from the buffer sw on the center terminal, wire to the buffer from an ignition-switched, and fused terminal. Really appreciate the thoughts and humor, George | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1367 Registered: 12-2000 Posted From: 76.68.122.153 Rating: N/A |
The combination of jakes and a retarder will still not load the driveline more than the engine. If you could get the bus to decelerate via driveline methods at the same rate it accelerates, then you need to start thinking about it... Depending on the type of retarder that is involved, they can be more powerful and have more levels of control than a jake, making their use for downhill control more flexible than a jake. In the modern equipment, my choice would clearly be a transmission retarder in a B500, not a set of jakes on the S60. What it is that FF is planning to do, versus what it can do, versus how it would actually be deployed... has gotten mixed up in the interpretation. happy coaching! buswarrior | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 353 Registered: 7-2006 Posted From: 70.210.162.152 Rating: N/A |
Yep....you are right on!!!!....I think..... What a great board, Ian!!!! Thanx George and BW... I needed that........ I think  RCB (Message edited by chuckllb on October 09, 2008) | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 149 Registered: 1-2007 Posted From: 208.81.157.90 Rating: N/A |
Another point that should be made is the issue of someone else driving or a new owner understanding a nonstandard Jake setup. If others are like me, they plan on taking their bus to the grave with them anyway, so it may be a non issue. Good luck Don 4107 | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 584 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
BW, I am guessing that it was a S50 with an HT70? Doesn't really matter, in my opinion. I agree with you that Jakes don't slow a bus as much as the engine can accelerate it. My question was concerning doubling the retarding effort, when both a trans retarder and Jakes were on at the same time. There has been no mention of judiciously using only one at a time? I also really question the amount of research done, when he can't even spell brakes, not to mention that an HT70 has been obsolete for years. We have all seen many posts from people who have bought things that can't work, then ask for help, so I would rather answer questions first. I would like to ask how many of us have both and an electric or trans retarder, and Jakes on a bus, and have used them both at the same time for lots of miles? George | ||
| R.C.Bishop (Chuckllb)
Registered Member Username: Chuckllb Post Number: 354 Registered: 7-2006 Posted From: 75.208.185.0 Rating: N/A |
Huh????..... George...you definitely lost me on that last one. I have Jakes (one switch on the dash)....and air brakes. If they don't do the trick, I shouldn't be driving a coach..... . Have a great day everybody. RCB | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 323 Registered: 2-2001 Posted From: 69.77.156.190 Rating: N/A |
George, exactly as you say. Seen from the driver's seat, all you can tell is double throw, center off (3 position). But when you open the panel, it is indeed double pole as well. One jumper across the center (common) terminals. One half bank on each terminal at one end, with a jumper from one half bank to the other end of the switch. That bank is energized when the switch handle is at either end. The second bank is energized just at one position. To make it easier for all. If you hold the switch vertically, and numbered the terminals from top to bottom, on the left would be 1,2,3, and on the right, 4,5 & 6. The half banks are connected to 1 & 2. There is a jumper between 2 & 5 and another between 1 & 3. Power goes to 2 (or 5). Hope that helps. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 586 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Jim, Thanks, that explanation makes it real clear for someone who is going to install two speed Jakes. RC, I believe what Fred was originally talking about, (which I guess we are talking about now) was an engine and transmission change. The new engine, if I have put together all of the previous posts correctly, would have about 125 horsepower more than the original. Then there was first going to be an HT740 with a retarder, which I don't think exists. Then it turned into an HT70?, which hasn't been made for many years. Anyhow, the posted intentions were to use BOTH Jake brakes on the new engine, AND a retarder on the transmission. A transmission retarder essentially uses two halves of a torque converter turning in opposite directions to each other to create retarding force by beating up the trans fluid and causing braking effort by creating heat. BW is correct in saying that Jakes alone are not as strong as an engine, but now we have 350hp 4-cycle of Jakes, (however you translate that into driveline effort) and however much effort the trans retarder puts out, all on a driveline originally designed for a 225hp 2-cycle, 2-valve(I think) engine. Copied straight out of the Jacobs web site, "reduces temperature swings when going downhill." What that means is that engines in Jake brake operation still put out SOME heat, and a trans retarder puts out a LOT of HOT tranny fluid, as that is just how it does its job, so lets hope he has made plans to get rid of a LOT of heat! So, I asked the question, and so far, nobody has come back and said they have a factory setup with full Jakes and a retarder, that has worked well for years. One post says "think I have one bank of Jakes with a factory retarder." A retarder is silent, and all I have seen give infinite control, which is nice, the only thing wrong with them is they add length to the trans... There are also electric retarders, but lets not mess up this thread any more. George | ||
| Jerry Coombs (Jerry_c)
Registered Member Username: Jerry_c Post Number: 3 Registered: 11-2005 Posted From: 205.188.117.73 Rating: N/A |
"A buffer switch out of adjustment will cause black smoke when the jake is on" ...I have a 4106 8V71 w/Jakes, 730 auto (3 speed with lock up) I have a dash switch to control the Jakes -- 3 postion OFF, low, high. I put a switch on the air throttle pedal so the SLIGHTEST movement will turn off the Jakes as well as that buffer switch back on the govenor. As I try to plan ahead as much as possible I often coast with out Jakes, turn them on "manually" (turn dash switch on high foot of accelerator pedal) if I think I need them, or just leave the switch on if I think I'm too occupied or in busy traffic to have that one more thing to do (turn on the Jake switch) QUESTION - I have long noticed if I have not used my Jakes for some time when I do there is a number of seconds where smoke (not quite so black like full throttle acceleration but maybe gray) will blow out the exaust when the Jakes are activated which starts to reduce after maybe 5 seconds or so (I often watch this in my rear view mirror) and then is very minimal at other Jake activations until once again I don't use them for some time. I often just guessed this was carbon / soot breaking loose from inside the muffler & exhaust pipes BUT COULD THIS BE THIS BUFFER SWITCH OUT OF ADJUSTMENT? Jerry | ||
| John Lacey (Junkman42)
Registered Member Username: Junkman42 Post Number: 57 Registered: 3-2007 Posted From: 69.19.14.42 Rating: N/A |
George, I made the statement that My MC7 has both jakes and a retarder! My transmission is a ht70. I have used both the jakes and retarder on a long down hill and it is very effective. The retarder will raise the transmission about 20 degrees and the engine temp about 10 degrees on a long downhill. I do not have a switch that allows partial jakes and do not know if I have one bank or both with jakes! John | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 589 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Jerry, If the engine doesn't throw black smoke, and doesn't die at idle, the buffer switch is properly adjusted. I agree with you that it is probably just blowing out carbon, etc. Jakes can pull some oil by the rings on worn engines, or a leaking blower seal may be letting some oil into the engine, which is burned clean in power, but shows grey in Jake? John, Are both of your valve covers 'tall,' and is there a wire running to each? If so, it sounds like full Jake. Pardon the pun! I guess there could be two masters on each side, and no slaves, but that's not the point. I appreciate your observations on temperature, and lets see how this plays out. George | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1368 Registered: 12-2000 Posted From: 76.69.140.166 Rating: N/A |
Hmmmm.... Hi Jerry. Jakes build air pressure in the cylinders and then lets it pop into the exhaust. I expect that this may introduce forces into the exhaust system that are somewhat different in temperature and style of force delivery than the regular exhaust pulses from a firing cylinder. As you have wondered, after some time of not engaging the jake, you get a little burst of "stuff" from the pipes that looks to be shook loose and then it works as advertised. I'm with you, shrug your shoulders? George, I'd be inclined to not use the wording of a jake "pulling" oil. Jakes are confusing enough to the uninitiated without introducing the idea that they create a vacuum in which to suck oil. If oil is getting in the cylinders when they fire, then oil will get in the cylinders when the jake is employed, via the same routes and in the same proportions, as for the purposes of this concept, the jake only changes that there isn't a fire in the cylinder on the power stroke, not that there isn't regular compression. Amazing where this thread has gone.... happy coaching! buswarrior | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 590 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
BW, There's sure enough thread here to weave a large garment. I'm shrugging my shoulders right with you. One picky little thing though, in power, fuel is injected at the top of the stroke, and the cylinder is under pressure all the way down. I know you know that, but what happens under Jake? Exhaust valves open at the top of the stroke, and all the pressure is released. The piston is pulled down by the crank, and if the rings are worn, they don't clean the cylinder walls, leaving a little oil behind in the cylinder for the next cycle? Regards, George | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 504 Registered: 10-2006 Posted From: 208.100.193.169 Rating: N/A |
Installing the nice heavy duty HT70 would have made the drive train too long by 6 or 8 inches. While a bump out in the back would have worked it sure would have screwed up the "look" of an antique Flx VL 100. A friend had a rebuilt ZF 600 tranny , 5 speed (one slight OD) and a built in retarder. Happily its LOADS shorter than the planned for 70 so with a Ser 50 should fit unobserved. "What I have never understood is why the jake switch is always some place you have to reach for it" Sounds like a wheel mounted set of switched would be the answer . By now they may have wireless units that would work, JaKe , retarder and tail light blink for thank you. The origonial coach had a 6-71 so the combination of both Jakes and Retarder might be beyond the axle torque limits. But of course the stock axle is the "wrong" ratio for best economy with a modern 4 stroke (even with mild OD) so a "better" axle may be waiting be at the scrap yard or rebuilders. IF the few pounds of air required to operate the brakes would actually cause the drums to touch is a question , so plan "B" could simply be a micro switch on the break pedal. FF | ||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 83 Registered: 7-2006 Posted From: 64.180.206.194 Rating: |
well i have read all the posts and i have still missed it,why would any one want so much stopping power that it would ripe the drive shaft apart? with all this stopping power would the next step be a cement wall? these coaches ran with only a hand brake and a poor designed air application valve and this was after they had hyd. brakes. the new 32 wheelers have jakes and engine retarders or tranny retarders and weigh in at over 76,000 pounds my 4104 is less than22,000 pds. and with the E6 app. valve and jakes on a DD that has a 2 valve head i still have no trouble stopping. some of the logging trucks in our area go over 200,000 pd. and they only have air and jakes. have any of you thought about using the water cooling system that they use? and the the boats have an anchor and shutle uses a shute, or would it be better to drive as though your life depended on it. or is it the need for speed which seems to kill a lot of innocent people that no braking system in the world could have prevented but a sensible driver would have. | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 506 Registered: 10-2006 Posted From: 208.100.193.43 Rating: N/A |
or is it the need for speed which seems to kill a lot of innocent people that no braking system in the world could have prevented but a sensible driver would have. The old rule was to go down the hill at the speed , in the gear you climbed it. Works great in our stick shift Sportscar 4106, but in the new coach the light weight and 5 speed gear box and 1000 lbs of torque should have the coach scream up hills at 75 , the way cars do. The plan is to descend those hills , at auto like speeds , in safety. The Jake or retarder plus the Jake should be able to hold the speed DOWN to 75 , and the combination WITH the std brakes should allow an emergency stop, with ease. This summer we ran a 17% grade in Canada , would have been nice to HAVE A JAKE AND RETARDER , and be able to "save" the chasis breaks. I'm simply looking for a simple way to have the Jake come on when I touch the break pedal, not simply lift my foot from the throttle, as we do coast at times, with NO braking desired. FF | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 329 Registered: 2-2001 Posted From: 69.77.156.190 Rating: N/A |
Hey Fred, both of our buses have a hard time getting up an 8% grade. How on earth does a bus get up a 17% grade? How long was this bus killer hill? | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 509 Registered: 10-2006 Posted From: 208.100.193.68 Rating: N/A |
" How on earth does a bus get up a 17% grade? How long was this bus killer hill?" At 17% it wasn't very long , about a mile , but the good news was there was a space before the hill to get wound up to max rpm.And no traffic lights. Sure would have been a killer to start on tho! In an old BC mag someone wrote a great article on selecting a rear axle ratio, and Start-ability. Haven't found the 1st gear ratio of the ZF H 5 -600 yet , or a site with good start-ability info yet. As the road in Canada was old , I wonder how teams of horses were able to get up it too? FF |
