| Author | Message | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Long story short, I just pulled into my driveway with my new (to me) Bluebird. It's a long long saga that started way back in November... I may post the story later but not quite yet. Anyway, this post is about Telma retarders. Back a few months ago I was chuckling as everyone here gave their opinions about how they work... obviously few if any had any firsthand experience with the things. Neither did I although I was in the process of purchasing one at the time, and I did add a few of my opinions too, but decided to wait for the real report when I had gotten it installed and had a chance to drive with it. So here it is: In the process of fetching this bus it died, and was towed to Don Fairchilds for a new engine. In the process, I also added a Telma retarder which I found locally at a junkyard. It took some newly fabricated brackets plus shortning the drivelines to get it mounted, and a bit of wiring, etc. Basically it was quite an easy job installing it. The model number of this one is CC100, which is capable of soaking up 737 foot pounds of torque, in 4 stages. (Telma makes smaller ones down to 368 ft pounds, and bigger ones up to 2211 foot pounds! ) The way it works is there are 4 relays that each hook the battery to one of four coils on the Telma, which then makes it's flywheels act as eddy current loads, just like a Dyno. Turn on one relay you get 1/4 of the retarding action; turn on all 4 and you get the whole thing, with two selections in the middle. (ie 4 stages) Telma makes a set of air-operated switches which I also installed... you hook them into your air brake line, and as you step on the brakes, they actuate the relays at 3, 6, 9, and 12PSI so the effect is that the Telma does your initial breaking and your drums come in later. How's it work? AMAZING. Now this bus is not yet converted so it weighed in at 16,500 pounds. That's obviously in the brakes' favor. But you can do the extrapolations. First, driving on a straightaway at 75MPH, turning all four sections on takes the bus to 55 in 4 seconds, and to 25mph in another 6 or so. It takes the bus all the way to 10mph before becoming innefective. Now get this: Doing this coming down the grapevine, a 6% grade, it took 8 seconds to take the bus from 75 to 55, another 5 seconds to 35, and I couldn't keep the test up 'cause trucks beind me where gaining on me much too quickly. My take on it as compared to the Jakes on my Crown: The Telma in only position "1" is stronger than my Crown with the Jakes full on, by about twice. Since the Crown weighs closer to 30k, it means the Telma is about 4x more effective. And mind you, it's mounted on the driveshaft so it doesn't make a bit of difference what gear you're in or you can even do it in neutral!! During a decent of a 6-1/2% grade in Laguna, I had to turn it off and on a few times-just in position 1 mind you- to keep from getting too slow. Amazing. The other nifty thing is that with the air brake connection, the Telma takes care of what appears to be about 90% of all braking, on the freeway and off. On the freeway, It is almost too good (can you get too good?) and makes fast stops a non-issue. There was one point in my 300 mile drive where everyone was panic-stopping and heading to the shoulder because they couldn't stop fast enough. Not me... it was actually possible to stop too quickly for my comfort with the folks behind me... something I've NEVER experienced in my Crown... So there you have it from the horses' mouth. I'm a believer, and If any of you ever had a doubt why 60% of all european heavy vehicles are now equipped with Telmas, I assure you they are happy customers and it's well worth the bucks if for nothing else than amazing safety, not to mention that service brake life appears to be 8-10 times longer for a given application when Telma-equipped, which pays for the Telma on it's own, safety notwithstanding. Are there any negatives? I'd say one, kinda... Each set of coils on this one draws 45 amps. So when using it full-on, it's eating 180 amps. This is no big deal because coming down a grade I can't see ever using more than stage 2, 90 amps, which the alternator can handle no biggie. Even if you used all 4 stages, the battery would take up the slack and be recharged later on. Still no biggie. What I don't care for is sitting at a traffic light with the brakes on and seeing my volt gauge go to 11, because when idling the alternator isn't working, so the battery is getting hit pretty hard at 180 amps. I honestly don't think it would hurt anything but I'm going to gin up a little electronic circuit that ties into the speedo sensor that disables the Telma under 5MPH. If that's all I have to complain about... oh well... Bottom line, was it worth it? YES Would I put one on if all I could find was a new one? YES WITHOUT QUESTION after today... WOW.... Cheerio.... | ||
| JW Smythe (Jwsmythe)
Rating: N/A |
Good review. Now I want one. | ||
| Brian Brown (Blue_velvet)
Rating: N/A |
As usual, nice write up Gary. Very informative. Thanks for going out on a limb with the new (to us) technology. It sounds amazing. Speaking of "new one", how much $$ for a bus-capable model? What'd you pay for yours? Just curious. Brian | ||
| akrom Rating: N/A |
75? In a bus? On the grapevine? Really now! akrom | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Yes 75 (rear end is 4.27, 12R22.5, bus can do 80) Yes in a bus...1990 TC2000 Bluebird Yes, on the grapevine, today is Saturday and everyone evidently in a hurry on the downhill side, and not much traffic- I could easily keep up...or not as I chose, safely Really now? Yes. Brian, I don't know what a new one is but I'm guessing about 5-7K. I paid $1500 for mine. I actually created the air sensor controls with parts from Ebay. I know a guy who got one for $500, a guy who got one for $200, and another who got one for $2000, so they are out there, although I think they are rarer than Autoshift trannys thus far...!!! | ||
| LOU MURDICA (Loucon)
Rating: N/A |
can I get one for a mc-9 8v92 | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
I believe so... here is a link describing their "focal" series for rear engine coaches http://www.winches-aust.com/WEBPAGES/telma/pages/Telma%20Focal%20Range.htm | ||
| Mark R. Obtinario (Cowlitzcoach)
Rating: N/A |
I have two mini-buses equipped with Telma retarders that I am parting out. If anyone is interested drop me a line. Mark O. | ||
| Tom Caffrey (Pvcces)
Rating: N/A |
Gary, does the Telma get rid of it's heat only with the the cast in rotor fans? And can the rotor get hot enough to interfere with the magnetic drag? Nice write up! Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Yeah Tom, that's where the energy goes...the rotors are fans and make hot air, and lots of it. It'll work up to the curie point of iron which is 760c or 1400f where iron becomes non magnetic. I seriously doubt it will ever get that hot (that's brighter than red hot) but it does definitely get toasty down there!! Being that coming down the grapevine I never really used more than position 1 out of four except for the "experiments", I doubt it will ever get into trouble. If you turn it on fully, you'd never get down the grade!!! (well, it'd certainly take a long time, cause you'd only be going 15mph) | ||
| John MC9 Rating: N/A |
(as the devil's avocado steps in....) Wouldn't it be terrible for the individual that becomes dependent upon it, when it fails to function..... (Hint: Go down the grade in the same gear that got you up that grade) | ||
| Jim-Bob Rating: N/A |
John, I guac what you said! (Pass the tequila, please) | ||
| John MC9 Rating: N/A |
*hic | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
"Wouldn't it be terrible for the individual that becomes dependent upon it, when it fails to function..... " No John, it wouldn't. (reminds me of Kyle on Southpark... "no dad, it's not") Just like Jakes, if it failed, my brakes will be nice and cool and quite ready to slow me down, as if I'd never used them at all. So it would turn into: Slow down to the speed & gear that you came up the grade with, and go down it the rest of the way at that speed/gear" No biggie Reee-dumb-dancie is groovy....  And though almost anything can fail, if ya do your homework on the install it can be made quite unlikely that it'll ever fail. These systems are pretty robust, time-tested and proven, and redundant in themselves as there are basically four separate electrical systems in the box...relays, not solid state... pretty darned reliable... ...but I guess there always has to be those disbelieving avocados.... (Message edited by boogiethecat on May 23, 2006) | ||
| John MC9 Rating: N/A |
"........coming down the grapevine, a 6% grade, it took 8 seconds to take the bus from 75 to 55, another 5 seconds to 35, and I couldn't keep the test up 'cause trucks beind me where gaining on me much too quickly......... .........On the freeway, It is almost too good (can you get too good?) and makes fast stops a non-issue. There was one point in my 300 mile drive where everyone was panic-stopping and heading to the shoulder because they couldn't stop fast enough. Not me...... " Not you, until they fail when you don't expect them to...? Not to belabor the point in my usual avocado style, but when they taught us how to drive buses, we had to drive as if we couldn't depend on brakes to stop us. The last thing any bus driver would do, is start down a hazardous mountain doing 75. (driving grades) That "warm fuzzy feeling" of security with brakes or brake assist units, can quickly become a warm squishy feeling in the seat of your pants.... when they fail. Don't get me wrong, the assists (Jakes, Telma, etc), are great to have; I'd love to have one in my rig! But those that get one installed shouldn't end up depending on the assist to do it's job. It's easy to forget just how much it takes to stop 11 tons at 75 mph. (and knowing -not- to use it on a slippery surface can avoid that sudden fatality....) "E's not dead, E's sleep'n; E's tired and E's sleep'n." (Monty the Python) | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
I'll engage you just this one more time John. First, please re-read and understand, this was a test and I did NOT start down the grade at 75. Never said I did. You're much too busy reading things in and not hearing what's being said, and you must not feel like you're heard because you tend to repeat yourself over and over. We all gotcha the first time... but time must be something you have too much of I guess...??? Once I started down the grade I felt things out and as I got the feel for it all, I TESTED, which meant speeding up when I was comfortable that it was ok to do. There was never much traffic around me or I'd have not done it at all but there was never a safety issue outside of normal. And as I've said so many times but you don't seem to grokk, when Jakes or the Telma in this case are working, the brakes are not. They're stone cold... a far cry from a vehicle without any auxillary retarding mechanism coming down the hill with it's brakes-a-cooking. So if the thing fails, the COLD brakes are easily able to slow the vehicle down once to a reasonable speed to maneuver the rest of the grade in a proper lower gear. Now yes Jakes and Telmas can fail. Heck so can we, and we do. 160,000 of us croak every day on this big round rock. So what? The point is that Jakes and Telma's are WELL designed safety systems with a damned good track record. They don't fail often, there is a lot of redundancy built in, and if they do, you deal with it. There seems to be quite a few people who live their lives in fear of "what if?" What if the Jakes fail? What if the Telma fails? Well, what if a tire fails What if a brake line fails What if your compressor fails What if your front axle fails What if your steering wheel fails What if the frame rails fail? ...you deal with it.... See where I'm going? All kinds of things can and will fail, and you can either be chicken little and just stay home out of fear, or you can get in your bus, have fun, and deal with stuff as it comes along. Personally I don't give a rats ars if my Jakes or my Telma fails because I can deal with it. I don't live my life in fear of "what if's".. If I did I'd not have a need for these bus toys because they would be too scary to even turn on... So John, please try to understand that I put the original post up to report what I found on my first trip with a Telma. I did not put that post up to be criticized right and left about the intangible future of how I am intending to use it, how much I'm going to get used to it, etc. One last little point... in the old days, yes the teaching wisdom suggested that you come down the grade in the same gear that you went up. But that was in the days when engines were not so powerful, brakes were not as reliable, Jakes were a curiousity and Telma hadn't even started a Corporation... Are you suggesting that if a bus has 600HP and can haul butt up a 6% grade at 65 in the top gear, that said bus come down the other side in the same gear at the same speed... especially if he ain't got Jakes or a retarder? I think not. The trick is to use common SENSE when coming down a grade, and that common sense has a lot to do with what the bus is equipped with, how complicated that equipment is, what it's mean-time-between failures is, how well maintanied it is, how well checked it is, etc. I'd suggest to you that you never get a Telma, also don't get a set of Jakes, and never fly on an airplane... 'cause what if they fail? EOE (End of engagement) Cheers...all in good avocado eatin' fun I like mine with CHPS Gary | ||
| John MC9 Rating: N/A |
Re: "time must be something you have too much of I guess...???" By John MC9 (66.217.107.160) on Monday, May 22, 2006 - 11:41 pm: By John MC9 (66.217.107.160) on Tuesday, May 23, 2006 - 12:28 am: By John MC9 (66.217.107.173) on Tuesday, May 23, 2006 - 9:19 pm: (Man... I never leave this blasted laptop!) Ok, seriously Gary... your test and critique of the Telma was great. It's an expensive system, and well worth the bucks for any bus or truck operator to have installed. Is it practical for -me-? Naww. Is it practical for anyone else that can't find one used, and does not run their bus daily for a few hundred miles or more, per day? Naww. Is it something that should be installed so one can traverse the mountainous regions without care? Your point was well taken. It's a great system for saving wear on the brakes shoes/pads and drums/discs. It can be an aid for keeping the brakes cool. But the bottom line is: no-one should rely on any brake system, or brake assist system. Only good common sense, and care must be taken when descending a mountain. A lower gear, and usually the gear that took you up the mountain, should be used to come down that same mountain. Yeah... I dwell on things like this too much. Sorry. I guess it always bothered me to see new drivers take so much for granted, and end up putting people at risk. Common sense isn't a prerequisite for a license to drive an 11 ton vehicle. There are even less prerequisites to own and drive a converted bus. It's still the same 11 ton vehicle, and carries the same hazards and dangers. It's always been my contention, that the same driving habits a professional bus driver uses, should be used by the private owner. Your "experiment" was great, as well your write-up and report! My comments were directed to the reader that is thinking of owning and driving a bus, and who has absolutely no experience of ever driving anything of the size or weight. (I've had skinner valves freeze on Eagles, while enroute to and from ski slopes. Knowing how to drive without brakes is more important than knowing what a "Telma" or Jake" is) Cheerios!! | ||
| Stan Rating: N/A |
snip <(I've had skinner valves freeze on Eagles, while enroute to and from ski slopes. Knowing how to drive without brakes is more important than knowing what a "Telma" or Jake" is)> snip Nobody should drive a bus without an auxillary braking system, at the very least a functioning emergency brake. It is the driver's responibilty to ensure that all brake systems are working properly. If the service brake system fails because of poor maintenance (there is no excuse for frozen valves) then you stop the bus with the emergency brake and park it until the maintenance is done. | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Hello. Gary, excellent report! You may want to rig up a parallel hand control so you may choose to activate without using the brake pedal. The new coaches have their hydraulic retarders set up with a 4 or 6 position joystick that falls readily to hand. As for the safety nazi-ism, perhaps we need to keep up with the times? In all driving, the principal has always been to keep the vehicle speed under control so that we may stop as it becomes necessary. In the city, around corners, on the highway, following distance and, yes, while running down steep hills. If you must rely only on the brake shoes to control a mountain descent, a slower speed must be used. If you plan to drag the brakes the entire slope, a slower speed must be used than if you plan to snub the brakes every so often. In order to go a little faster, the supplemental use of engine compression and gear selection is used to control the speed. Why? Because higher speeds will quickly render the brakes less than effective due to massive heat build up. So, despite standing on the brake pedal, the vehicle will speed up and run out of control. Typically, no vehicle's brakes have been sized to accomodate the heat build up when the combined forces of highway speed and down-the-mountain gravity are being controlled. So, we go slow with this configuration because the brakes have their limits to both control our speed and stop us if it becomes necessary. If you have Jakes or a retarder, you may safely descend the mountain at higher speeds than those who only rely on the brakes. These devices have been specifically designed to do this job. Depending on the device, the heat generated by them is dumped into the engine coolant, the transmission fluid and/or the air around the vehicle. They leave the brake drums & shoes, as noted in earlier posts, nice and cool, and able to decelerate the vehicle with their full potential intact. Have you noted the large number of trucks and buses that pass us as we descend the slopes? Have you noted the absence of daily reports of run-away commercial vehicles in mountain areas? In order to serve the newer and less experienced bus conversion driver, we need to have balanced reporting! There are different methods required for different vehicle configurations. None is better than the other, they are simply different. There are technologies that emerged somewhere in the middle times, and there are technologies emerging as we speak which will all change the safe and proper methods drivers use to ply the highways and byways. Let's be sure that we keep up, speak to specific configurations and put things in perspective for those who need info. Otherwise, folks are misled, and that's unsafe! happy coaching! buswarrior | ||
| niles steckbauer (Niles500)
Rating: N/A |
BW - We need to change your handle to BusMediator - LOL Gary - you are one busy resourceful guy - thanks for the info - when you get enough mileage on that thing I think we'd all be interested in know how the batts and electrical system is holding up (though it doesn't sound like your gonna draw that much current with the weight of that bus using stage 1 or 2) and maybe speculate on whether something with a little heavier GVW might need a beefier system - if you have a hitch on that thing let's try towing a 10k plus trailer on the next test, what do you say? | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Actually Niles, that's going to happen. On my upcoming trip to Burning Man, I expect the bus to weigh in more like 22k, and I'll be towing a 6,000 pound trailer. I'll definitely put in a report, and will be able to give you some more insight on how it responds to more weight. I'll also be posting some pics of the install in the next few days. Right now I'm busy raising the roof and moving the door back to behind the front wheel. While I'm not going to give Cap'n Ron a run for his money for sure, I only have 12 weeks to get the roof raised, door moved, the siding back on, painted, plumbed, and a lot of the interior stuff done... eeek.... | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Gary... Pictures from Burning Man, from a busnut's perspective, of course, would be quite educational for all us wanna bees... happy coaching! buswarrior | ||
| Tom Caffrey (Pvcces)
Rating: N/A |
Gary, if the Telma has no indicator to let the driver know how hot it is getting while in use, do you think it might be worth installing a dedicated infrared thermomter for that purpose? I also had the same thought about the foundation brakes. Tom Caffrey PD41062576 Suncatcher Ketchikan, Alaska | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Tom, I'll probably do some thermal checking but my guess is that Telma has done some pretty extensive research into that already, and it's likely that if they did fade, we'd be hearing about it here and there on the internet. Maybe I'll call them and ask.. wouldnt that be a novel idea!! But the next time I'm driving, I'll take the IR thermometer along and check immediately after a grade and see what the temp is down there. The thing that helps it all out is that as things get hotter, they give their heat to the air more easily. So since this is not a friction thing that will catch on fire if it gets real hot, I think the only thing to worry about is if the wheels get red hot and loose their magnetic properties. And I don't see that happening due to all the surface area and fan blades cast in to the wheels... It's not like it's going to fade like brakes. It's more of a binary thing... it's magnetic or it isnt. But an interesting point to ponder, if it ever did reach the curie point, because it would no longer be dumping bus energy, it would immediately cool off to below that point, and quickly equalize itself right on the edge between magnetic and non magnetic. I guess that might be felt as a fade out... I still can't imagine red glowing flywheels down there, spinning at 1800 rpm... eeek keep the fuel lines away!!!! (Message edited by boogiethecat on May 25, 2006): Just in... talked to my physicist friend just now. Black bodies radiation of heat into still air increases with temperature to the fourth power ! This is accentuated greatly when moving air is involved. Thought of in another way, as the temperature differential between ambient and your hot thing increases, heat goes away faster and faster (increasing on a 4th power curve) as the hot thing gets hotter. Probably the reason you don't hear about Telma's fading out...VERY difficult to get the flywheels hot enough to die.. I'll still do the measurements and report. (Message edited by boogiethecat on May 25, 2006) | ||
| John MC9 Rating: N/A |
buswarrior - Good points, well taken. And yes, I have been out of the loop for awhile. If the technology warrants going downhill at breakneck speed, I suppose it's safe to do so? Trust into the Jake or Telma, and the brakes as last resort... The old farts like me, will continue to be the slow dog all the way to the the bottom.... with or without assistance. |