Bobtailing
Printed From: Unofficial Allis
Category: Other Topics
Forum Name: Shops, Barns, Varmints, and Trucks
Forum Description: anything you want to talk about except politics
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=175220
Printed Date: 09 Sep 2025 at 5:48am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Bobtailing
Posted By: ACinSC
Subject: Bobtailing
Date Posted: 16 Oct 2020 at 7:59pm
| Been wondering this for a long time . When I was a truck driver 40 years ago we could only drive 45mph bobtailing . What's different now that 70 mph is ok ? Thanks |
Replies:
Posted By: Brian Jasper co. Ia
Date Posted: 16 Oct 2020 at 8:14pm
|
I have driven spring ride and air ride tractors. On a rough road no way would I drive an unloaded spring ride 70. The tandem dumps the state has can get a little squirrely empty on a rough road, I can only imagine how fun they would be as an incomplete vehicle.
------------- "Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford |
Posted By: tomNE
Date Posted: 16 Oct 2020 at 8:40pm
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35yrs ago we drove the speed limit; which varied widely throughout the states! ------------- AC from the start of my families farming career till the end! |
Posted By: klinemar
Date Posted: 17 Oct 2020 at 6:02am
| Brian,I agree with you about State Highway Plow Trucks ! The one I drove had Hendrickson suspension and when scraping snow with an underbody blade you wanted to keep a sharp eye for frost heaves in the road as the suspension would throw the truck about! Some guys claimed they could scrape at 45 mph. I didn't! |
Posted By: ACinSC
Date Posted: 17 Oct 2020 at 8:22am
| We were told that if you hit the brakes bobtailing the tractor might spin like a top . Thanks ! |
Posted By: Lars(wi)
Date Posted: 17 Oct 2020 at 8:26am
|
I remember back when semi tractors didn’t have brakes on the steer axles. ------------- I tried to follow the science, but it was not there. I then followed the money, and that’s where I found the science. |
Posted By: DMiller
Date Posted: 17 Oct 2020 at 8:38am
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Can remember REMOVING Steer brakes on road tractors in the 70s as was NOT illegal yet. With ABS there is a false sense of security in being able to stop while bobtail or even just empty trailer. I still leave stopping distance gaps as they will still slide even with ABS as the system ONLY works if one wheel still retains traction telling the controls that have wheel lockup on the others, they ALL lock down same time ABS does not see a problem.
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Posted By: TomC
Date Posted: 17 Oct 2020 at 8:40am
| I was an owner operator from 1974 until this past April & retirement. Roads haven't changed much except for way more congestion, trucks haven't changed except way more power. What has changed way,way,way more is big nuts right behind the steering wheel,, and not for the better. |
Posted By: DMiller
Date Posted: 17 Oct 2020 at 8:41am
| Them be LOOSE Big Nuts behind the wheels!! |
Posted By: ACinSC
Date Posted: 17 Oct 2020 at 8:57am
| Way back when I drove we had a paper graph that tracked our speed . Thanks |
Posted By: Coke-in-MN
Date Posted: 17 Oct 2020 at 9:18am
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When I quit driving tractor/tanker the company went from 68 MPH to 62 MPH limit in computer - and it seems local driving and home every night became Omaha , Chicago, Mandan SD , and a few more routes where freeways speeds were 70 and you impeded traffic with you foot to the floor .. Bobtailed a few times to pick up new trailers in WI , Ill, and Iowa but most times drop a trailer at a place to get it certified and run to another place to pick another trailer up 100 miles or so away . Air ride Pete as the tractor . Ya Hendricks suspension on a dump when empty can give quite a ride on rough road - counter-steering to keep front end straight in direction of travel as rear decided which way it was going to go next. ------------- Life lesson: If you’re being chased by a lion, you’re on a horse, to the left of you is a giraffe and on the right is a unicorn, what do you do? You stop drinking and get off the carousel. |
Posted By: TomC
Date Posted: 17 Oct 2020 at 10:07am
| Suspensions make a difference in the ride, the big difference in bobtailing is the ability to slow down ,stop or control. On wet roads it's going to be 2 to 3 times longer to stop,on ice or snow??? You are not going to stop or slow down, an empty trailer is a little better but not much. From what I saw in the past 10 years and only gets worse by the week is a large percentage of the people these companies are putting in trucks these days are not able to grasp just plain old walking around sense. |
Posted By: DMiller
Date Posted: 17 Oct 2020 at 11:08am
I remember Tachographs, can remember drivers destroying the charts as they could get into them or knowing how to 'Unplug' Speedo. If could not do that as with the old haulers in STL they just beat the mechanisms until quit and claimed were trying to get them to function so would not get fired, worked for a few.
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ACinSC wrote:Posted By: ACinSC
Date Posted: 17 Oct 2020 at 11:36am
| Some driver's put rubber bands on the needle arm so it would show 10 mph slower . Remember one guy had his too tight and the graph never got over 15 mph . Uh oh ! |
Posted By: ac fleet
Date Posted: 19 Oct 2020 at 2:51pm
|
only had to do it a few times ----- that was one thing I refused to do and boss respected my wishes. When I did it I never ran anywhere near the limit and on wet roads even slower---on snow and ice----they sent somebody else. I am still alive and still enjoy part time runs now and then. ------------- http://machinebuildersnetwork.com/ |
Posted By: DMiller
Date Posted: 19 Oct 2020 at 4:48pm
| Was instructed DECADES ago now that a Tandem Dual Wheel semi has LESS CONTACT SURFACE Weight on the back wheels bobtailing than a standard VW Beetle on four tires, looks impressive but contact surface weight spread means there is next to nothing gluing that machine to pavement. Hit the brakes all the weight shifts forward so the rears lock out or ABS Kicks in and NO STOPPING in any reasonable distance. We were then told NO MORE than 2/3 maximum speed of the machine when bobtail and DOUBLE stopping distances. |
Posted By: TomC
Date Posted: 19 Oct 2020 at 5:14pm
| I believe it was put to me like this" it's like trying to roller skate uphill " |
Posted By: ACinSC
Date Posted: 19 Oct 2020 at 7:13pm
| Thanks for all the replies . Guess it's still a good idea to take it easy bobtailing . |
Posted By: Dakota Dave
Date Posted: 19 Oct 2020 at 7:57pm
| back in the 70s we had no traction bias ply lump lump till they warmed up tires almost no brakes front drums and no antiskid. the trucks we drive now are much better they will for the most part stop even on wet slushy roads brakes are more controllable the old ones were on or off pretty much in between. the massive power increase makes it much easier to spinout accelerating empty. i dont rember farm trucks having that problem back then we usually couldnt get up to hiway speed with a full truck |
Posted By: SteveM C/IL
Date Posted: 19 Oct 2020 at 8:23pm
| Bobtailing 600hp is like driving a sports car! |
Posted By: TomC
Date Posted: 19 Oct 2020 at 8:31pm
| Let me know which way you are going,,, cause I am headed the other direction |