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Car Forum / Driving, Maintenance, Tuning / RVs / August 2005RV mountain driving brake issues
I have owned three RV's. A late 70's Winnie, and 84 Winnie on a P-30 chassis, and now a 1993 Itasca diesel on an Oshkosh chassis. All three have had perfectly adequate brakes for normal driving when well maintained. None of them have had good enough brakes to make it down a good western US mountain grade without multiple stops to cool the brakes. My current Oshkosh chassis has 4 wheel discs. Even using engine braking to it's limits and braking intermittently to allow as much brake cooling as possible between applications, heat overwhelms the brake system on long mountain downgrades. Clearly it would add a lot of expense to an RV to design and install the huge and well cooled brakes necessary for good performance on mountain grades. I am interested in hearing comments on mountain braking techniques and experiences from other RV travelers. Do you have an RV that can handle long steep downhills without overheating the brakes? Are modern class "A" diesels equipped with much better brakes? I doubt it but am interested to hear. Have you changed out your brake pads for special aftermarket pads? Changed to larger rotors, etc? How about best possible driving strategy? (I use engine braking with a lower gear to help as much as I can, but my old Allison 4 speed will upshift on its own when it hits too high an RPM) I tend to use firm application of the brakes for five to ten seconds followed by no brake pedal pressure for as long as the speed stays down with tranny braking to allow brake cooling. Is constant on and off brake pedal pressure better? Other comments? I can't imagine that you actually stop "multiple" times to cool your brakes on downgrades. Did you mean that you pull over and stop, then wait for the brakes to cool? On all three RVs?? Something doesn't add up. Are you towing a big trailer or toad without trailer brakes? What do you call a "good western US mountain grade"? Would the 5 mile grade dropping off the Grapevine on I-5 towards Bakersfield count? In years of driving big rigs I never had to pull over to cool brakes, and RVs don't begin to have the braking challenge that a loaded big rig does. And I've circled the entire country in my lowly F53 Rexhall Vision 32' and never had to stop to cool my brakes. On a typical 5% grade, I can easily maintain a safe descent with OD off, braking down to 50 MPH or so, then coasting back to 55-60 MPH before slightly braking again to reduce speed to 50 MPH, then repeating as necessary. On steeper grades I have dropped down into 2nd and done similarly, keeping the speed from about 30 MPH to 40 MPH or so. Never a problem, never a brake fade issue. hmmm. I think I might be misunderstanding your post.  SignatureDale Gillespie My Homepage: www.FishWisher.com My RV Site: http://groups.msn.com/CoachpotatosRVHomepage/_whatsnew.msnw >I have owned three RV's. A late 70's Winnie, and 84 Winnie on a P-30 > chassis, and now a 1993 Itasca diesel on an Oshkosh chassis. All three [quoted text clipped - 36 lines] > > Other comments? >I can't imagine that you actually stop "multiple" times to cool your brakes >on downgrades. Did you mean that you pull over and stop, then wait for the >brakes to cool? On all three RVs?? Something doesn't add up. Are you towing >a big trailer or toad without trailer brakes? Ya. Somethings funny here. I lost my brakes twice while in Colorado (My first time in the Rockies). I talked to a Colorado Springs brake tech. and I realized what I was doing wrong, plus he told me if I've never changed the fluid, it had to have water in it and it was boiling, which in turn made me lose (not LOOSE :) the brakes. Knowing that, I was able to take my 26' class C up and down Pike's Peak without any problem, plus I never had another problem with them the rest of the trip. I did, however, change the fluid, front calipers, and bled all 4 ends when I got home. >I have owned three RV's. A late 70's Winnie, and 84 Winnie on a P-30 > chassis, and now a 1993 Itasca diesel on an Oshkosh chassis. All three [quoted text clipped - 34 lines] > Is > constant on and off brake pedal pressure better? Service brakes are not designed to provide sufficient braking capacity for long mountain descents. That's why you need to gear down, and only use the brakes periodically to maintain a target speed. Diesels typically have limited engine braking unless the engine is equipped with something like a "Jake Brake" (which changes the valve timing to increase braking, and is quite noisy), or an exhaust brake. I would check on exhaust brakes, since they are likely more practical for your application. Do a Googl search for "exhaust brakes (use the quotation marks) to find various manufacturers. SignatureD.J., N8DO; FMCA 147762 dj[underscore]osborn at yahoo dot com > (I use engine braking with a lower > gear to help as much as I can, but my old Allison 4 speed will upshift on > its own when it hits too high an RPM) This is clearly your problem.....the transmission does not STAY in the lower gear and effectively brake the motorhome. I have no problem going down hill in my 33 ft Seabreeze motorhome on the 18000 lb Ford F-53 chassis, but the transmission stays in the lower gear no matter WHAT revs the engine goes to. It's my job as driver to stab the brakes to keep the RPM below the red line, and I've never seen them fade. I cannot get into low gear at speeds over 35 mph, nor into second at speeds over about 55 or 60...and I must be sure I stay under those speeds if I think I need to downshift....but it does keep the speed from running away with only occasional stabs of the brakes. With the transmission ready to shift up, you MUST keep the speed below that which causes the upshift by stabbing the brake.... Are you trying to go down steep hills too fast for engine braking to work in your vehicle?? HTH, Barrie B I have read two different ways to use your brakes going down a slope. 1. Use your brakes hard for a few seconds, then let off to let them cool before using them again. 2. Keep a slight pressure constantly. By not applying full pressure, you build up less heat, therefore giving the rotors a better chance to use the cooling fins that are built into them. I don't know which is the best. Good luck Hank <~~~ Will brake for food Ninebal, Do not use technique #2. That is exactly what will overheat your brakes. Instead, brake hard to get down to a lower speed, then down shift. Then only apply brakes when you have to (never constant pressure) CD >I have read two different ways to use your brakes going down a slope. > 1. Use your brakes hard for a few seconds, then let off to let them [quoted text clipped - 8 lines] > > Hank <~~~ Will brake for food > I have read two different ways to use your brakes going down a slope. > 1. Use your brakes hard for a few seconds, then let off to let them [quoted text clipped - 8 lines] > > Hank <~~~ Will brake for food I have no definite data, but this subject has been discussed at length, and the approach I accepted as most credible is to stab them, then let off. It seems the uniform pressure approach can result in lower peak temperatures IF all brakes apply uniformly when lightly pressed. Most folks believe there are imbalances between the brakes on each wheel in the real world, which become less significant as more pressure is applied. Thus the wheels share the heat load better if the brakes are periodically stabbed, then released. FWIW, Barrie B >I have read two different ways to use your brakes going down a slope. >1. Use your brakes hard for a few seconds, then let off to let them [quoted text clipped - 4 lines] > >I don't know which is the best. Your approach #2, slight, constant pressure, is the way I was taught when I started driving a big rig back in 1974. It has since gone out of favor. The reasoning behind the constant pressure was that the stab and release method tended to cause the brake linings (remember, we're talking drums, not disc brakes here) to heat up and cool down too fast too often, causing a glaze on the shoes. The end result was that the glazed surface of the brake shoes rubbing on the smooth metal surface of the drums was the equivalent of trying to stop a 73,260 lb rig going down a ??% grade by rubbing two pieces of glass together. Perhaps somebody can answer the question as to whether the composition of the brake shoes changed somewhere along the way that caused the change in method? Greg > I have read two different ways to use your brakes going down a slope. > 1. Use your brakes hard for a few seconds, then let off to let them [quoted text clipped - 4 lines] > > I don't know which is the best. *If* the brakes are *all* perfectly adjusted --so that each wheel's brake does *exactly* the same amount of work as *all* of the others--then (according to the experts) either method works equally well. However, experience has shown the experts that brakes are *not* all perfectly adjusted. Therefore, while method Number 2 used to be the recommended method, it no longer is. Method Number 1 is the preferred method, and is the one that's taught in the Commercial Driver's License manuals. SignatureD.J., N8DO; FMCA 147762 dj[underscore]osborn at yahoo dot com >How about best possible driving strategy? (I use engine braking with a lower >gear to help as much as I can, but my old Allison 4 speed will upshift on >its own when it hits too high an RPM) I tend to use firm application of the >brakes for five to ten seconds followed by no brake pedal pressure for as >long as the speed stays down with tranny braking to allow brake cooling. Is >constant on and off brake pedal pressure better? Engine braking is very poor with a diesel. Adding an exhaust brake, if one can be fitted, would definitely make a difference, but otherwise I would have ask "What lower gear?" If 3rd doesn't work, use 2nd. If 2nd doesn't work, use 1st. If that means you have to go down the hill at 15 mph, so be it. This isn't a problem with a typical newer big rig with a large diesel and engine or exhaust brake. My rig, with towed car, weighs in at 30,000 lbs. With an 8.9L diesel and exhaust brake, I can take the mentioned Grapevine (very even 6% for 5 miles) at 56-58 mph in 4th gear without ever touching the service brakes once. SignatureDon Bradner donb at arcatapet dot com www.arcatapet.net > Do you have an RV that can handle long steep downhills without > overheating > the brakes? The answer is yes!! You also have a rig that can handle the down hills without over heating. As others have pointed out, you are going too fast for conditions. Get in a lower and lower gear until you can maintain speed with very little braking. You soon learn how much speed gain makes your tranny shift up and stay below that speed. I go down many grades in 2nd and some in 1st. The main goal is to reach the bottom of the grade while on the paved highway, not as fast as you can over the edge of the mountain. Sane drivers go down using very little braking by gearing down low enough to maintain speed. Now, about your tranny. I have never had a tranny that shifted up on it's own accord. If I ever do have such a tranny, it'll go back to the dealer until the problem is fixed. Tom J >> Do you have an RV that can handle long steep downhills without >> overheating [quoted text clipped - 15 lines] > >Tom J Uh, Tom, the Allison in the Duramax will upshift when the rpms reach about 4500 rpms. Self preservation. Many transmissions will upshift when the rpm range exceeds the safe engine speeds. SignatureFrank Tabor >>> Do you have an RV that can handle long steep downhills without >>> overheating [quoted text clipped - 27 lines] > upshift > when the rpm range exceeds the safe engine speeds. If a driver is letting RPM's get that high before down shifting or braking, they are unsafe drivers and are asking for disaster!! Tom J >>>> Do you have an RV that can handle long steep downhills without >>>> overheating [quoted text clipped - 32 lines] > >Tom J Lots of folks out there have no idea what they are doing, driving 45 foot buses and 55 truck/fiver combos and tagalongs. Lots of them don't know how to drive a car, let alone a lethal combo consisting of a RV. They aren't unsafe, they just don't know any better. They don't understand that they have to take some action to slow the vehicle themselves. After all the brochure said the transmission would downshift and slow them on the downgrade. No one told them they had to apply the brakes also. Not everyone is an over-the-road driver and knows all about going up and down hills. That's why the manufacturer put the function in for a forced up shift at high rpm. Self preservation. SignatureFrank Tabor [snip] >They aren't unsafe, they just don't know any better. They don't >understand that they have to take some action to slow the vehicle >themselves. After all the brochure said the transmission would >downshift and slow them on the downgrade. No one told them they had >to apply the brakes also. I beg to differ Frank. These people are horribly unsafe. They are a menace and a rolling murder potential. >Not everyone is an over-the-road driver and knows all about going up >and down hills. That's why the manufacturer put the function in for a >forced up shift at high rpm. Self preservation. Maybe not but they should be. If you are going to play with the big boys, you better know the rules. We all have learned some things the "hard" way and hopefully did so at our own expense only. Of course, that is what insurance is for <G>. unk >[snip] >> [quoted text clipped - 6 lines] >I beg to differ Frank. These people are horribly unsafe. They are a >menace and a rolling murder potential. Maybe so, but they are in the vast majority of RV operators. God looks out for fools and drunks. Here in this group and in RORT we only get a very tiny sample of the total number of RVers out there. And the vast majority big a big honking RV and jump in it from their compact car and have zero knowledge of what they are supposed to be doing. Maybe they are unsafe. But check the statistics, on the whole, RVs figure in a very small percentage of crash statistics. >>Not everyone is an over-the-road driver and knows all about going up >>and down hills. That's why the manufacturer put the function in for a [quoted text clipped - 3 lines] >boys, you better know the rules. We all have learned some things the >"hard" way and hopefully did so at our own expense only. See above. >Of course, that is what insurance is for <G>. > >unk SignatureFrank Tabor >Now, about your tranny. I have never had a tranny that shifted up on >it's own accord. If I ever do have such a tranny, it'll go back to the >dealer until the problem is fixed. Is there such a thing as a modern automatic transmission coupled to a Diesel that won't upshift to protect the engine from over-revving? SignatureDon Bradner donb at arcatapet dot com www.arcatapet.net > >Now, about your tranny. I have never had a tranny that shifted up on > >it's own accord. If I ever do have such a tranny, it'll go back to the > >dealer until the problem is fixed. > > Is there such a thing as a modern automatic transmission coupled to a > Diesel that won't upshift to protect the engine from over-revving? I think all modern automatic transmissions will upshift at some point to protect the engine. For the Duramax diesel and Allison transmission you have to get up to 4600-4700 rpm to red-line and I have never had mine get over 4500 rpm. By the way, it isn't a quiet diesel when it gets over 4000 rpm ;-) Ron >> Do you have an RV that can handle long steep downhills without >> overheating [quoted text clipped - 15 lines] > > Tom J All tranny's will up shift when maximum Rpm is reached, especially on diesels, and that is to protect the engine from over revving, that is the first indication that he is descending to fast for the gear selected. The last thing you would want to happen is to loose the engine and go freewheeling down the mountain. Wade >>> Do you have an RV that can handle long steep downhills without >>> overheating [quoted text clipped - 34 lines] > last thing you would want to happen is to loose the engine and go > freewheeling down the mountain. I've never owned 1 that upshifted, but maybe it's because I know how to safely go down a mountain grade! :-) I've seen enough of someone else over the side to know I don't intend to take the short way down!! Tom J polite rant: Surprising and a little sad that some in this group jump to the conclusion that you are an incompetant boob if you start this kind of thread. I would think that if I posted that I make brake cooling stops on very long and steep western down grades, readers might think I was overly cautious, rather than assume that I go down grade too fast. I thank those who posted some useful and accurate information. Anyone interested in some of my mechanical experience, visit www.longacres.com/personal.htm Amoung other things we are in the off-road mud racing business. We know a bit about braking. polite rant over > I have owned three RV's. A late 70's Winnie, and 84 Winnie on a P-30 > chassis, and now a 1993 Itasca diesel on an Oshkosh chassis. All three have [quoted text clipped - 27 lines] > > Other comments? > polite rant: > Surprising and a little sad that some in this group jump to the [quoted text clipped - 6 lines] > cautious, > rather than assume that I go down grade too fast. Polite rant OK, but I still say that if you find it necessary to pull over and stop for brakes to cool on any highway in North America, you are in the wrong gear or something is wrong with your rig, whether 18 wheeler fully loaded. auto, vehicle towing travel trailer or motorhome with toad in tow. I driven all the above plus commercial busses, and only once in 48 years of driving have I had hot brakes. I forgot to release the parking brakes that time!! Tom J >I still say that if you find it necessary to pull >over and stop for brakes to cool on any highway in North America, you >are in the wrong gear or something is wrong with your rig, whether 18 >wheeler fully loaded. auto, vehicle towing travel trailer or motorhome >with toad in tow. I agree. The only time I ever ended up on the side of the road with too-hot brakes was my first trip down the Grapevine in 1971 with an overloaded tractor-trailer, and that was absolutely because of trying to come down at the same speed as the jake-brake-equipped rigs traveling. The rigs I drove back then had neither engine nor exhaust brakes, and it was necessar to choose a much lower gear and go down slower. SignatureDon Bradner donb at arcatapet dot com www.arcatapet.net "Tom J" <tomj_ga@despammed.com> wrote > I driven all the above plus commercial busses, and only once in 48 years > of driving have I had hot brakes. I forgot to release the parking brakes > that time!! > > Tom J We drive to LA and southern California a lot. On the California side of Cajon Pass, there is a steep downgrade into Berdoo. I am constantly amazed at how many big rigs have hot brakes. They are either smoking, or when you go by, you can smell that unmistakable smell. You'd figger those boys would have it down pat by now. Guess it must be the newbies. On that downgrade in the last ten years or so, they have also lost two freight trains that had brake failures. Now, THAT'S about as scary as it gets. IIRC, the first crash took out a couple of houses and damaged a gasoline pipeline. They didn't discover the damaged pipeline until they had a carbon copy event in the same area, and then that took out more houses, and threw in tens of thousands of gallons of burning gasoline just for effect. Still, I smell lots of brakes on Cajon Pass. Is it just me, or do you freak out when you smell brakes or clutch and wonder if it's your vehicle? Steve >"Tom J" <tomj_ga@despammed.com> wrote > [quoted text clipped - 27 lines] > >Steve Just because they smell, doesn't mean they are overheated. They aren't overheated until they smoke. Just making a normal stop will produce a noticeable smell. SignatureFrank Tabor > On that downgrade (Cajon Pass) in the last ten years or so, they have > also lost two freight trains that had brake failures. That's not quite correct. In the case of the BNSF freight (the more recent of the two), it was discovered that there was a closed angle cock buried not too far back in the train. This prevented the air from from passing through the train, so its brakes did not fail, but rather it had no brakes at all in the rear portion of the train. This accident led directly to an FRA rule requiring that rear-end devices continually monitor brake pipe pressure at the rear of the train and report that condition to the engineer. In the case of the SP train, it was found that the consist was seriously overloaded for the the braking horsepower of the train; it was an error in calculation by a Yardmaster, IIRC, that allowed the train to go out seriously overweight. Both trains were being operated by well-trained, experienced engineers. The accidents happened as a result of conditions beyond their control. These are two of the scariest railroad accidents in recent memory (except perhaps for HazMat problems in the Texas area). Ken H >> On that downgrade (Cajon Pass) in the last ten years or so, they have >> also lost two freight trains that had brake failures. > > That's not quite correct. <treatise on brake terminology and function snipped> Sorry I was not exactly precisely correct. In my mind, when one puts on the brakes, and they don't work, I describe it as brake failure. I am a simple person, and perhaps I oversimplified. My apologies. Maybe they just had some water in the brake fluid. Steve > Sorry I was not exactly precisely correct. In my mind, when one puts > on the brakes, and they don't work, I describe it as brake failure. > I am a simple person, and perhaps I oversimplified. My apologies. I'm not trying to be "snippy," Mr. B., but merely trying to bring into focus the differences between how truck and train brakes (and perhaps how truck drivers and locomotive engineers) work. I think it is safe to assume that truck drivers who go down the west slope of Cajon at speeds that will overheat their brakes are fools of the first order, endangering not only themselves but all around them. That seems to have been one of your points, and you are spot-on. I've also seen these cowboys northbound over Siskiyou Summit. Railroaders (and I am not one of them, incidentally) are a significantly different breed. No engineer would knowing operate a train in a manner hazardous to his or any other person's well-being. So what I am suggesting is that a runaway truck is the driver's responsibility; a runaway train is a much more complicated subject, and not necessarily (or at all, in the case of the SP and BNSF examples) a reflection of the capabilities of the crew operating the train. Being interested in the railroad industry, I am always sensitive to how it is portrayed in the press, or even in places such as this newsgroup. I'm sorry if I over-reacted. Ken > That's not quite correct. In the case of the BNSF freight (the more > recent of the two), it was discovered that there was a closed angle cock [quoted text clipped - 16 lines] > > Ken H I have no knowledge of this accident, however if that was the story from the railway then something is very fishy here. In airbrakes the air is required to disengage the shoes from the wheels, having no air to the cars in the back would have brought that train to grinding halt. Wade > I have no knowledge of this accident, however if that was the story from > the [quoted text clipped - 3 lines] > back would have brought that train to grinding halt. > Wade Be very careful, Wade. You are bordering on insinuating that this might have been a "brake failure." 1 a : omission of occurrence or performance; specifically : a failing to perform a duty or expected action b : a state of inability to perform a normal function <kidney failure> -- compare HEART FAILURE c : a fracturing or giving way under stress <structural failure> 2 a : lack of success b : a failing in business : BANKRUPTCY 3 a : a falling short : DEFICIENCY <a crop failure> b : DETERIORATION, DECAY 4 : one that has failed Webster's version inserted for pickers of nits. Steve ;-) Unless the air was set before the angle cock was closed. Back in the 70's the former BN had the same thing happen to a coal train at Clareton, WY. I was working in Lincoln, NE for the mechanical dept. at the time. I talked with one of the people that investigated the wreck and he told me a closed angle cock was the cause.tOn Wed, 10 Aug >> That's not quite correct. In the case of the BNSF freight (the more >> recent of the two), it was discovered that there was a closed angle cock [quoted text clipped - 22 lines] >back would have brought that train to grinding halt. >Wade : I have no knowledge of this accident, however if that was the story from the : railway then something is very fishy here. In airbrakes the air is required : to disengage the shoes from the wheels, having no air to the cars in the : back would have brought that train to grinding halt. : Wade Are you sure about this? I know that a lot of truck brakes work this way but I also remember spending a lot of time around a freight siding when I was in my teens (many decades ago). Back in those days, the brake shoes hung loose and the freight cars could be moved by hooking a tow chain to a truck or even by one man with a special lever which was applied between the rail and a wheel. Either of those methods would have failed if the brakes were automatically ON when disconnected from the train. Next time I go by the local freight yard, I will have a look at the brake shoes on the cars parked there and confirm this for myself - one way or the other. Ben F. > Are you sure about this? I know that a lot of truck brakes work this way > but I also remember spending a lot of time around a freight siding when I > was in my teens (many decades ago). An interesting article on freight train brakes: http://www.tarorigin.com/art/Jbentley/ SignatureChris Bryant http://bryantrv.com > An interesting article on freight train brakes: > http://www.tarorigin.com/art/Jbentley/ ...and that is one of the clearest explanations I have ever seen for train brake operation. Extrapolating those explanations will illustrate why a closed angle cock might very well have caused the BNSF runaway on Cajon. Earliest railroad air brakes were simply straight air, where an application applied brakes directly to the wheels. Problem was that there was no storage of air on each car, so air was quickly depleted from the locomotive's air tanks. Straight air was quickly relegated to streetcar operation; even the interurbans (set up for multiple-unit operation) used some sort of automatic air system. KH : > An interesting article on freight train brakes: : > http://www.tarorigin.com/art/Jbentley/ : ...and that is one of the clearest explanations I have ever seen for : train brake operation. Extrapolating those explanations will illustrate : why a closed angle cock might very well have caused the BNSF runaway on : Cajon. : Earliest railroad air brakes were simply straight air, where an : application applied brakes directly to the wheels. Problem was that : there was no storage of air on each car, so air was quickly depleted : from the locomotive's air tanks. Straight air was quickly relegated to : streetcar operation; even the interurbans (set up for multiple-unit : operation) used some sort of automatic air system. : KH I have not yet checked out the link given above, but .... ... on thinking a bit more about the ones that I saw a long time ago, my bet would be that they were *steam powered, rather than air?? This would make the obvious time for a changeover, from 'pressure to apply' to 'pressure to release', seem to be shortly after everyone converted to diesel power, and needed compressors and pressure tanks which obvoiusly proved to be less than reliable - for the reason stated above. Interesting! .... and when I have a bit more time, I will check out the link - which will probably either confirm or shoot down my thoughts stated here. :-) Ben F. > I have not yet checked out the link given above, but .... > [quoted text clipped - 10 lines] > .... and when I have a bit more time, I will check out the link - which > will probably either confirm or shoot down my thoughts stated here. :-) There is a somewhat more in depth article here: http://www.sdrm.org/faqs/brakes.html Which is incredibly interesting. The brakes are pressure apply, but each car has a tank which is pre charged- once it is charged, any *reduction* in the air line pressure activates a valve which apply tank pressure to the brakes. It really is a fascinating subject- something I had not though about before. SignatureChris Bryant http://bryantrv.com : > I have not yet checked out the link given above, but .... : > [quoted text clipped - 10 lines] : > .... and when I have a bit more time, I will check out the link - which : > will probably either confirm or shoot down my thoughts stated here. :-) : There is a somewhat more in depth article here: : http://www.sdrm.org/faqs/brakes.html : Which is incredibly interesting. The brakes are pressure apply, but each : car has a tank which is pre charged- once it is charged, any *reduction* : in the air line pressure activates a valve which apply tank pressure to : the brakes. : It really is a fascinating subject- something I had not though about : before. This gets more interesting all the time. Thanks Chris, for the URL and the explanation above. BTW, your good advice and 'voice of reason' are one of the main reasons that I still follow this sometimes hot-headed, and sometimes hollow headed, newsgroup! Ben F. > BTW, your good advice and 'voice of reason' are one of the main reasons > that I still follow this sometimes hot-headed, and sometimes hollow > headed, newsgroup! Me, too. This is where the best RAILROADING tech talk can be found on the net. :) JR > ... on thinking a bit more about the ones that I saw a long time ago, my > bet would be that they were *steam powered, rather than air?? Not hardly! I believe there were steam brakes on some 19th Century European lines, notably in the UK, but little if any in the Western Hemisphere. How does one apply brakes if a steam line should break? As a point of interest, railroad brakes on (most) British railroad equipment are vacuum, not pressure, actuated. Ken H > polite rant: > Surprising and a little sad that some in this group jump to the conclusion [quoted text clipped - 15 lines] > >===\ This is RORT! Half a dozen nice guys. The remainder seem to have a mental problem :-) Geoff. > " >> [quoted text clipped - 4 lines] > Geoff. >)0ops I guess it's NOT RORT. Getting that way though LOL Geoff. I'm going to hazard a guess that your Itasca is a '93-'94 with a 4 speed Alllison AT-542 on an XC series Oshkosh. I own one under a Safari and have experienced similar problems on isolated occasions. What you must realize is that the AT-542 does not use a lock-up converter as the later 5 and 6 speed units which results in very little engine braking when downshifed while descending grades. The result is usually higher transmission temps. Because of the non-lockup trans, adding an exhaust brake is not really an option. I suspect that you have moisture in the braking system as I did. The master cylinder mounted above the left front wheel likely contributes to the water ingestion.. Ah....if I only knew then what I know now! Good luck > I have owned three RV's. A late 70's Winnie, and 84 Winnie on a P-30 > chassis, and now a 1993 Itasca diesel on an Oshkosh chassis. All three have [quoted text clipped - 27 lines] > > Other comments? |
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