| Author | Message | ||
| Gary Stadler (Boogiethecat)
Rating: |
Howdee you Crown guys... I have to report (gloat gloat) that I just finished putting a set o' Jakes on my Crown Cummins 220. It was not a "straightforward" job but it wasn't bad. Such a good sound to hear that "chugeda chugeda" the first time I hit the Jake solenoids with 12 volts!! If any of you Crown guys with Cummins motors have any inclination to be as nutty as me and add a set of these, email me and I'll be happy to tell you all the hoops I went thru, where to get a good used set, all the things you'll have to order from Cummins, and all the things to watch out for. The biggest hassle of it all was finding where the stupid engine timing marks were, to adjust the valves and injectors (took me 4 hours just to find them... they weren't where the manual said they were!) and once found, how to actually see the fool things...that's one issue that Crown didn't put any thought into at all, and it is a nightmare. I ended up sticking a video camera up in there and let it sit all contorted and upside-down under the bus instead of me.. made the valves & injectors real easy to adjust after that!! Now I can't wait for my next trip!! Cheerio | ||
| R.C.Bishop
Rating: N/A |
Didn't have to go thru all that you talk about since mine came with Jakes. I have also found my manuals,(2) with every conceivable possibility, to be very accurate. Could be you have the wrong manual for the engine you have...OR? At any rate, sounds like you are are "up and running". BTW...when the Jake switch is on ( on my rig) the engine kills if you get down to an idle. Won't start with the Jake on and is very reliable down to abou 7-10 MPH. Sure saves using the brakes a lot....We use it all the time, but never always. FWIW RCB '64 Crown (HWC) | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Hi RC, you lucky guy... I have the right manuals... there's all these teensey details that are really easy to miss like special washers you gotta use if you have aluminum rocker housings, 2 different diameters of jake injector adjustment screws (and of course my jakes came with the wrong ones), always that one silly gasket you forget to order, and since I stuck my own turbo on, all the mods I had to do for that too like spacer bocks which weren't stock parts stuff. The Cummins manuals (I have three) all stated that the timing marks are on the flange of the vibration dampener for horizontal engines. Well not on a Crown...they're stamped in the teensey narrow edge of the pulley closest to the engine where it's almost impossible to see. And totally not obvious with even the tiniest amount of dirt. You "should" have a switch on your gas pedal and another on your clutch that are set up so that either kills 12 volts to the jake selector if the pedal is down, so theoretically it will run at idle as long as your foot is not on the gas or the clutch is in. Fun with the Crown | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
The Jakes should cut off at about 1000 rpm as I recall, so that the engine can continue at idle speed indefinitely. Although I never did, I have talked to a few nuts that always left the Jake switch on and they never had a problem with ideling. As I recall, I think it cuts off when the oil pressure get too low to keep the hydraulic cylinders on the Jakes open. Richard | ||
| R.C.Bishop
Rating: N/A |
Richard...as I think about it...never having looked at the matter from the Tach point of view, you have nailed it pretty close to that 1000 RPM. I'll have to watch that to see how it plays out on our coach. Gary...also never considered the foot not on the pedal or clutch approach. Seems to me that might be an awkward situation under any circumstance. Not at all difficult to "flip the switch" so imagine we'll continue doing that. But I can tell you the first time the engine wouldn't start (because the switch was left on) I had a few anxious moments...  Thanx for the info. RCB | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
I got it a bit wrong in my last sentence... it will run as long as the clutch is in, or if your foot is ~on~ the gas. This way if you have the jakes on and you need some power, you just step on the gas... and if you come to a stop & put the clutch in, it will idle. Then theoretically if you decide to go from a stop, you'd put the gas down as you let the clutch out, and between the both of them it would keep the jakes off while accelerating. Changing gears though, they might surprise you if you double clutch or shift without gears... interesting logic to think thru. When I had the exhaust brake installed (until last week) it was also disabled by the throttle pedal, and that worked very well. So I'll see how this works out... Today I'm doing the wiring. Since I already have two convenient spare wires going back to the engine, instead of using three separate circuits I thought I'd just do it with two circuits by hooking Jake 1 & 3 together at the engine. This way if I want only one jake I'd turn on #2...if I want two jakes I'd turn on the 1+3 combination... and if I want all three I'd flip both switches. Seems like there should be no problem doing this??? | ||
| R.C.Bishop
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KISS.......Try one (1) You might like it....Good grief!! .... RCB | ||
| Richard Bowyer (Drivingmisslazy)
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Gary, the way I understand how it should work is that if you press the clutch in it opens the Jake circuit or if you press the fuel feed it opens the Jake circuit or if you turn off the ignition switch it turns the Jakes off. Typically there is a micro switch on the rack called the buffer switch that turns the Jakes off when the accelerator is pressed. Adjustment of this switch is critical and should increase the engine rpm by about 25 rpm when it is adjusted correctly. One double pole, double throw, center off switch is the correct switch. Wire it so that in the up position power is applied to each bank of jakes, in the lower position power is applied to one bank of jakes and center off turns off both jakes. Richard | ||
| Ron Walker (Prevost82)
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To add to Richards comments, the buffer switch also turns off the Jakes when the RPM's get down around 800 to 1000 (it's adjustable) There also a micro switch, with a 6" long spring wire off the switch, that rests on the under side of the clutch pedal arm that turns off the Jakes when you depress the clutch I have 2 switchs ON/OFF and HI/LOW If you need an electrical schematic email me. Ron | ||
| Richard Bowyer (Drivingmisslazy)
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Thanks Ron for the clarification. I did not recall what actually turned the jakes off at low rpm. Do not have my manuals anymore. Richard | ||
| Henry R. Bergman, Jr. (Henryofcj)
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Gary....thanks for the great info. Way back in 1970 or sooooos when I was pretending to go to college and before I got myself drafted, I drove part time as a school bus driver for the Kern High School District in sunny Bakersfield CA. Old #21 was a 1963 Crown 10-wheeler with flat glass and a 220 Cummins hooked up to the Spicer 5-speed. The engine had a Jake Brake. One could Jake the engine down to zero rpm stalling it if your foot was not on the clutch or throttle. The Jake also did not want to really work until the water temp (and oil?) got up to around 140 degrees. Once the engine warmed up, it worked great. Could come down the Ridge Route with 50 kids at 25 mph in 3rd gear without touching the service brakes. But what was really neat is that you could use the Jake to quickly slow down the mill when you upshifted, which was really neat starting up a steep hill. The trans matched up real quick while double clutching. Now I have a real stupid question to ask after you have gone to all the work doing all the work installing your own very own Jake. Would it have been easier to just drop the entire engine, install the Jake, then rehang the mill? Just curious and please don't kill me. CROWNS FOREVER!!!! | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
I just got done wiring everything, and it came out exactly as Richard suggests. Throttle switch, clutch switch, and two rocker switches on the dash with a big red light telling me it's on. All that (but the light) also matches the Jake manual circuitry. I did do the two-switch thing for selecting 1,2,or 3 jake banks though... just like binary, it's easy to select three power settings with two wires, and convenient for me because I happened to have two spare wires going from the dash to the engine compartment. Switch 1 turns on the middle bank and switch two turns on both the front and back banks. So with the two switches I can select 1,2, or all three. Henry, I can't imagine dropping the engine for anything except replacing it!! NO, for heavens sake this was a very easy job to do from the engine compartment. The whole job took me three fairly lazy days. Dropping the engine would take a week out and another week in... it's massive AND to get it out from under the bus you'd have to either have a lift, a pit, or cut out a load of siding. I'd love to figure out a way to disable the jakes when the engine is below a certain RPM.. I'll probably create some sort of frequency sensor circuit that steals pulses from the tach sensor, and opens a relay below a set frequency. I'll let you know if I decide to do this... gotta take it for a long drive first to make sure it'd be worth the trouble. Thanks for the suggestions guys! Happy Jaking... | ||
| Richard Bowyer (Drivingmisslazy)
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I think that you will find that as the engine rpm drops down to 1000-1200 rpm that the Jake action will be insignificant. It really only works good, in my opinion, above 1500 rpm and really works great above 2000 rpm. Richard | ||
| Gary Stadler (Boogiethecat)
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That makes sense Richard...however the Jakes will certainly kill an idling engine...I could see some situations like shifting to a higher gear without the clutch, where you let off the gas and shift into neutral, then drop the shifter back in when the engine's at the right speed... This all happens with the clutch engaged and foot off the gas pedal, so it seems to me that if on, the jakes would take the engine down in RPM very quickly like Henry mentioned... if you were to miss that shift (which happens), it could result in stopping the engine- a messy situation at best. So it would be nifty to have a system in place that absolutely turned the jakes off say under 1000 rpm, at least I'd think so. But for now, I've never driven a Jake (coming up in two weeks) so it's all conjecture for me. I'll know more when I mess with it for real.. Cheers | ||
| pat young
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Wow, you guys are walking dictionaries. I printed out the whole thing for my files on Cummins and Jakes. Thanks a lot for sharing your experiences. Patrick Young | ||
| RJ Long (Rjlong)
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Patrick (and others) - If you go to www.jakebrake.com, you can download and save the installation manual, operator's manual, parts book, and other service publications for free. Detroit, Cummins, etc. All in Adobe .pdf format. FWIW, RJ PD4106-2784 Fresno CA | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
Gary, I am guessing that Jake action at low rpm or idle depends on the shape of the engine and maybe whether it is two or four stroke, adjustments and oil pressure at idle. I had an 8V92 with automatic transmission and the Jake would not kill the engine when I came to a stop. I could leave the switch on all the time if I so desired. When I came to a stop, I could hear the Jake action down to about 800 rpm and then it quit working. Based on that, I do not believe the Jake , if everything is adjusted properly, will kill an engine. Richard | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Hi Richard, well, if the Jake control solenoids are energized when the engine is trying to idle, it will kill it 100% of the time. Your 8V probably has a sensor on the oil pressure (or elsewhere) that de-energizes the jake solenoids at low rpm. So far mine doesn't. As of the date my Jakes were manufactured, nobody had figured that out yet...keep in mind my engine uses model 20 jakes, the first ones to ever be made. By the time 8V's were manufactured, Jakes and their control systems were a lot more mature. So for mine, presently, the only three things that can disable the jakes are: My rusty old brain (Panel selector switches) Throttle switch Clutch switch You know how Jakes work, right? At around TDC on the power stroke (at least for my Cummins 220, a 4 stroke) a hydraulic piston takes energy from the injector rocker and transfers it to a piston that pushes on the exhaust valves, thus letting out all the air compressed on the compression stroke. No compressed air, no cylinder fire. The engine dies a dead duck. If I turn on only one bank of Jakes at idle, the engine will still run on the remaining working 4 cylinders, but rough as heck and it would likely break a motor mount or worse, something in the engine. It's REALLY rough. Turning on two (or all three) banks at idle kills it immediately. So it's all about exactly what you say, causing "Jake action down to about 800 rpm and then it quit working" ie somehow getting the Jakes to be disabled below 1000 or maybe 800 RPM. In your case there is probably a control system in place that does that regardless of throttle or clutch position; in my case there is not unless I concoct one. RJ, I checked the jake site and they have a nifty 75 page troubleshooting guide that covers my particular Jake as well as loads of others. I have it wired exactly as shown under the heading "Basic wiring diagram for non-electronic 3-mode system". Elsewhere in the PDF they mention an electronic system called "Low speed engine retarder cutoff" for later models that is exactly what I was considering... it steals a signal from the engine's flywheel tach sensor and absolutely cuts the jakes off under a set RPM that is between 850 and 1060 RPM depending on the engine. This was implemented way after my system was manufactured, and it's probably what I'll do if I have any troubles... Bottom line, I can probably learn to get past all this because the Jakes were wired this way for many years, but on the flip side, there's nothing like a little electronics to help us old farts out when our brains forget to turn things off... Cheers | ||
| Tom Caffrey (Pvcces)
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Gary, if you install a pressure switch that is fully adjustable, I would think that you could set it so that when oil pressure dropped towards idle RPM, the Jake circuit would open. Going at it from the fuel end, I believe that there is zero or near zero fuel pressure delivered to the fuel injectors anytime that you are slowing down under compression with a PT system, which I think is the system your Cummins uses. If that is right, then you could set a switch to open the Jake circuit anytime there was fuel pressure. It might be interesting to give one of those schemes a try. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
I do not know whether mine had an oil pressure switch or what, but you definitely did not have to turn the Jakes off at idle. In fact, as the engine speed was slowing down you could actually hear the Jakes quit working at about 1000 rpm. Richard |
