sclord2002 Posted October 27, 2015 Report Share Posted October 27, 2015 Dollytrolley, in all fairness, it appears that the spring vs air ride test that Schneider conducted was on TRAILER suspensions exclusively. I don't think that it would be fair to assume the exact same conclusion on the TRACTOR suspension without conducting a tractor specific test....bobtail and at various loads. Not trying to be argumentative [well, not TOO much] but just stating my opinion. I think discussion is healthy and will welcome any comments that don't involve questioning the marital status of my parents or something of the like. I really do enjoy your stories [you should write for magazines] and wit and will look forward to other folks take on the spring vs air ride on tractors. BTW, I would have thought the air ride would have been head and shoulders above the springs on trailers but that was not the case in the Schneider testing. I have been all wet on some of my previous attempts at thinking and I could be dripping now.. I do have air suspension on all 3 of my 780 axles. Just my $0.02 worth. What think ye ?? Charlie Bounce on.........[and tell which is less punishing] Don't ever tell a soldier that he doesn't understand the cost of war. Link to comment Share on other sites More sharing options...
rickeieio Posted October 27, 2015 Report Share Posted October 27, 2015 Had a Hendrickson suspension on my old '84 Volvo/GMC/White. No springs, air or otherwise. Calling it rough is being generous. Switched to an air ride Mack with the same (short) wheelbase and thought I'd gone to Heaven. Bought the '01 Volvo and just had to hook up to the grain trailer and try it out before converting to MH status. Holy Cow, what a ride. So, while I still have the Mack for the farm tasks, I can occasionally appreciate the differences between trucks. If you really want to experience a punishing ride, jump into one of my cousins' R models........ Ride along...............(let your behind gather the data).................... KW T-680, POPEMOBILE Newmar X-Aire, VATICAN Lots of old motorcycles, Moto Guzzi Griso and Spyder F3 currently in the front row Young enough to play in the dirt as a retired farmer. contact me at rickeieio1@comcast.net Link to comment Share on other sites More sharing options...
Mark and Dale Bruss Posted October 28, 2015 Report Share Posted October 28, 2015 At their load rating, steel springs and air spring have very close to the same deflection for force ratio. Air springs have the advantage of changing the load rating. Extremely important on the rear suspension of a tractor where is can go from no hitch load to maximum hitch load. Cargo trailer can benefit from air spring where the trailer load can go from half to full GVWR capacity. The front suspension of a tractor has almost no benefit from an air suspension as the front axle loading is almost consistent from no hitch load to full hitch load. An RV trailer is almost a static load. You seldom move several hundred pounds into or out of the trailer. As such, the advantage of air springs having a variable load rating, is not a real advantage. The belief that air spring are softer comes from one of the easiest implement in pickups. Spring for the trailer load with steel springs meant the pickup had a near solid suspension and rides like bricks. Having the pickup equipped for an empty weight with steel springs meant the truck rode pretty well. Using air springs to handle the additional trailer weight gave the belief that the air springs gave a better ride. In reality, the spring rate, deflection versus force is the same. Please click for Emails instead of PM Mark & DaleJoey - 2016 Bounder 33C Tige - 2006 40' Travel SupremeSparky III - 2021 Mustang Mach-e, off the the Road since 2019 Useful HDT Truck, Trailer, and Full-timing Info atwww.dmbruss.com Link to comment Share on other sites More sharing options...
phoenix2013 Posted October 28, 2015 Report Share Posted October 28, 2015 Cooter, it has been done in 1997. I was running a company full of very bright engineers, we were making money, decided to spend a little (lot) to "have some fun". Designed and built few of these. Custom hitch pin instrumented with a strain gauge. Incidentally, just throwing few acceleratometers here and there will not necessarily do the trick. We went through couple of these pins before we got one that worked. There are a lot of forces in all axis and they have a tendency to swamp the ones you are interested in. A premiere strain gauge company finally helped us to engineer the pins to sense only what we were interested in and ignore all the others. The pin was instrumented so it would would sense and measure only the shear force between the truck and trailer which turned out to be, Here's the visual plot of an aggressive stop with truck brakes only, trailer electric brake being turned off. The truck weighed about 7K the trailer, a 32 footer with two axles with torsion bars springs was about 8K. Note that the entire braking cycle lasted about 4 seconds (from 50 mph) and the maximum shear force developed was 3,454 pounds or just unde 1/2 G. But also note that it immediately rebounded almost 2,000 pounds and then went up almost , 1,000, then held relatively steady at 2,500, before dissipating relatively quickly to zero. Things got really exciting with the electric brakes on the fifth added to the mix. This is a test, can anybody analyze what is going on here. A clue. Link to comment Share on other sites More sharing options...
Dollytrolley Posted October 28, 2015 Report Share Posted October 28, 2015 On my post #13 I ask: So Crazy and forum members here is a quiz question......... Why were the engine vibration plots of a higher amplitude when BOTH engines and props were feathered (stopped) in the glide-testing, than when both engines were running? Correct answer gets a cold Dr. Pepper My point is that vibration testing can be a …....adventure sometimes....... Drive on ….......(Glide with care........) Question 2: Right engine had most amplitude because it was furthest from left elevator flutter. bja, Close enough for a cold Dr. P................"Prof Too Tall" would likely fill up three large blackboards full of eginvaluees, signz, cosinngzz, diffequaznz and, and to "ex-plane" what the vib-source is .......ya know the drill .......but you have the right idea..... Ya gotta love vibration testing..........sometimes shutting the engine off just makes things worse.......how do you win...... Drive on.......(Only good vibs allowed.....) 97 Freightshaker Century Cummins M11-370 / 1350 /10 spd / 3:08 /tandem/ 20ft Garage/ 30 ft Curtis Dune toybox with a removable horse-haul-module to transport Dolly-The-Painthorse to horse camps and trail heads all over the Western U S Link to comment Share on other sites More sharing options...
Dollytrolley Posted October 28, 2015 Report Share Posted October 28, 2015 Cooter, it has been done in 1997. I was running a company full of very bright engineers, we were making money, decided to spend a little (lot) to "have some fun". Designed and built few of these. Custom hitch pin instrumented with a strain gauge. Incidentally, just throwing few acceleratometers here and there will not necessarily do the trick. We went through couple of these pins before we got one that worked. There are a lot of forces in all axis and they have a tendency to swamp the ones you are interested in. A premiere strain gauge company finally helped us to engineer the pins to sense only what we were interested in and ignore all the others. The pin was instrumented so it would would sense and measure only the shear force between the truck and trailer which turned out to be, Here's the visual plot of an aggressive stop with truck brakes only, trailer electric brake being turned off. The truck weighed about 7K the trailer, a 32 footer with two axles with torsion bars springs was about 8K. Note that the entire braking cycle lasted about 4 seconds (from 50 mph) and the maximum shear force developed was 3,454 pounds or just unde 1/2 G. But also note that it immediately rebounded almost 2,000 pounds and then went up almost , 1,000, then held relatively steady at 2,500, before dissipating relatively quickly to zero. Things got really exciting with the electric brakes on the fifth added to the mix. This is a test, can anybody analyze what is going on here. A clue. Yo Henry.......... You-R-Da-Man......... So.....are those two goons with the spaghetti-sauce-stains on their Italian silk shirts in the Blues-Bro dark glass's in the dark-window-van across from your driveway........are they.......Hit-men from the "Electric-Trailer-Brake-Assn.-of-America (ATBAA....)... ....just imagine how rich the first tort-lawyer will get after you step-off the "expert-witness-stand" after pointing at all of....."the points" on the plot-from-hell......wow One thing for sure.......after looking at your #2 plot ..... you better hope that your electric trailer plug is UN-PLUGGED the next time you tow down a slick road.........maybe broken wires in a electric trailer brake systems are ....a safety feature.... Drive on.........(Brake.....with care.....) 97 Freightshaker Century Cummins M11-370 / 1350 /10 spd / 3:08 /tandem/ 20ft Garage/ 30 ft Curtis Dune toybox with a removable horse-haul-module to transport Dolly-The-Painthorse to horse camps and trail heads all over the Western U S Link to comment Share on other sites More sharing options...
Star Dreamer Posted October 28, 2015 Report Share Posted October 28, 2015 Here's the visual plot of an aggressive stop with truck brakes only, trailer electric brake being turned off. The truck weighed about 7K the trailer, a 32 footer with two axles with torsion bars springs was about 8K. Note that the entire braking cycle lasted about 4 seconds (from 50 mph) and the maximum shear force developed was 3,454 pounds or just unde 1/2 G. But also note that it immediately rebounded almost 2,000 pounds and then went up almost , 1,000, then held relatively steady at 2,500, before dissipating relatively quickly to zero. Things got really exciting with the electric brakes on the fifth added to the mix. This is a test, can anybody analyze what is going on here. A clue. On the diagram with the trailer brakes, it looks like the first spike was application of the truck brakes, next dip was when the trailer brakes activated effectively reducing the initial shear, then basically back and forth due to the brake controller sending intermittent signals. I can't seem to figure out why the last spike except that maybe a delay in the trailer brakes releasing. 2005 Freightliner Century S/T, Singled, Air ride ET Jr. hitch 2019 46'+ Dune Sport Man Cave custom 5th wheel toy hauler Owner of the 1978 Custom Van "Star Dreamer" which might be seen at a local car show near you! Check out http://www.hhrvresource.com/ for much more info on HDT's. Link to comment Share on other sites More sharing options...
Dollytrolley Posted October 28, 2015 Report Share Posted October 28, 2015 Dollytrolley, in all fairness, it appears that the spring vs air ride test that Schneider conducted was on TRAILER suspensions exclusively. I don't think that it would be fair to assume the exact same conclusion on the TRACTOR suspension without conducting a tractor specific test....bobtail and at various loads. Not trying to be argumentative [well, not TOO much] but just stating my opinion. I think discussion is healthy and will welcome any comments that don't involve questioning the marital status of my parents or something of the like. I really do enjoy your stories [you should write for magazines] and wit and will look forward to other folks take on the spring vs air ride on tractors. BTW, I would have thought the air ride would have been head and shoulders above the springs on trailers but that was not the case in the Schneider testing. I have been all wet on some of my previous attempts at thinking and I could be dripping now.. I do have air suspension on all 3 of my 780 axles. Just my $0.02 worth. What think ye ?? Charlie Bounce on.........[and tell which is less punishing] Sclord....... Below I have pasted part of the Schneider position paper and it appears to me that indeed they consider the rear truck suspension as a vital factor in the total ride quality of the complete vehicle-combo........at least that is my read on it........ I have both spring and air suspended trucks so I am........ "sort-of-a-mongrel-dog-in-this-fight"......... Tell ya all this.....my old 2000 Caddie still rides better than ANY truck........ Position Paper // SPRING RIDE VS. AIR RIDE schneider.com To ensure its fleet is outfitted with the best suspension system, Schneider ran an extensive series of tests between various air- and spring-ride suspension systems to compare the ride quality of the suspensions with three freight weights – 10,000, 30,000 and 40,000 pounds. The company ran a series of vibration and acceleration trials using and comparing the values of acceptable ride condition (ARC) and the maximum g-force (the maximum force transmitted) to determine ride quality. Conducted with the load weights mentioned above, Schneider tested the industry standard spring suspension against four common air suspensions. The four air suspensions that were chosen represent the majority of suspensions in use today. The tests consisted of: • Ride quality at the front of the trailer: The ride quality of the freight in the front of the trailer was examined and tests showed that the front ride quality was a function of the tractor suspension, not the trailer suspension, proving that the trailer suspension had little effect on the ride quality of the freight. • Ride quality at the rear of the trailer: The graph (right) shows the industry standard spring suspension compared with the average results of the four most popular air suspensions, proving that the average ride quality of the top four air suspensions is very close to the industry standard spring suspension. In fact, under most circumstances, the spring-ride suspension provided a better ride quality. Drive on..........(Try to avoid the pot-holes......) 97 Freightshaker Century Cummins M11-370 / 1350 /10 spd / 3:08 /tandem/ 20ft Garage/ 30 ft Curtis Dune toybox with a removable horse-haul-module to transport Dolly-The-Painthorse to horse camps and trail heads all over the Western U S Link to comment Share on other sites More sharing options...
Refuzn-To-Grow-Up Posted October 28, 2015 Report Share Posted October 28, 2015 SWAG to Phoenix's question . . . . brake chucking that occurs on a typical 5'er hitch (but NOT on ET's). Link to comment Share on other sites More sharing options...
budeneighe Posted October 28, 2015 Report Share Posted October 28, 2015 ... Depends on the brake controller and it's activation/hotshot/application characteristics..... On/Off vs Pulsed vs Proportional (inertia based - prodigy) vs True force proportional (brakesmart / Hayes / etc.). RVBuddys Journal Our progress into full-timing.Budd & Merrily ===-> SKP# 088936 Other Websites:---> Hub of all my blogsClifford - 2000 VNL64T770 :: DakotR - 1999 C40KS King of the Road :: $PRITE - 2013 Smart Passion w/cruise Link to comment Share on other sites More sharing options...
CrazyCooter Posted October 29, 2015 Author Report Share Posted October 29, 2015 I'm going to do a simple pull test with both trucks this weekend for some simple data and double checking hitch height before we head out on the next trip. I'll share what I find although I'm not sure how good the info will be using a simple smart phone. Probably should plan on getting an air damped solution back on there provided there is any trailer left when we get back. 1999 Peterbilt 385 C12 430/1650 13spd 2006 Dodge 3500 DRW 4x4 2010 Hitchhiker Champagne 36 LKRSB Link to comment Share on other sites More sharing options...
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