Actual Literature on Towing and Spatial Considerations of Driving

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steelmooch

Well-known member
Joined
Aug 5, 2010
Posts
280
Hello, everyone...and thanks for your time and consideration. 

Besides "time on the road", and the fact that there's no substitute for experience, I was wondering if anyone could refer me to any type of literature dealing with the driving of a large vehicle/rig and towing. 

We all know about "tail swing", but I'm truly interested in learning more about it...for a given length of vehicle, I'd like to see diagrams of the phenomenon.  If you were to change to a longer/shorter vehicle, or to a tandem situation, what happens to the amount of "swing" then?  How does the track of the rear wheels differ from that of the very front wheels?  Etc. 

In almost a "free body diagram" (physics) sense, I'm interested in learning more about safe RV driving and TT towing...can anyone refer me to a website or to a book that would cover this in a somewhat detailed, and even mathematical, manner? 

Thanks! 
 
Most information that i've seen published about this is more aimed at Commercial applications. I would search CDL manuals.
 
The rear tires of a motorhome will track inside the path of the front tires when turning. How much so depends on how sharp the turn is, and the RV's wheelbase. We have a windy road leading to our house, and the rear tires of our previous 28 foot MH would always be inside the lane markers on the sharper corners, however it's impossible to keep the rear tires of our current 43 foot MH inside the lines on those corners. I have to wait for oncoming traffic to pass, then pull into the opposite lane slightly to make the turn.

Both of our towed vehicles pretty much follow directly behind the MH while turning. That's because the distance between the MH's rear wheels and the towed vehicle's front wheels isn't very much, and our towed vehicles are narrower than the MH.

Tail swing was a bigger problem with our 32 foot gas MH than with either our 28 footer or our 43 foot DP. That's because the 32 footer's overhang was longer. That, combined with its shorter wheelbase, caused a greater tail swing - especially when turning sharply. That fact enabled me take out a truck driver's mirror one day at a double left turn lane (Unfortunately, I was on the inside lane.) Basically, if the rear of the MH can make the turn without without hitting something, the towed vehicle will also clear the turn.

I understand what you're asking about regarding the math of your questions, but every different wheelbase, overhang length and turn circumference will change the answer, somewhat. In my opinion, the best practical method of learning about your particular MH's turning characteristics is to go to a parking lot with a tape measure and somes cones, and measure exactly how far the rear end of your MH swings while turning as sharply as you can.

Kev
 
Going to theoretical to lab...
Take the rig and a couple friends to an empty parking lot with some colored sidewalk chalk.  Make turns while the friends mark wheel position and rear end location on the pavement.  You can make wide turns, sharp turns, left or right turns.  Take pictures and / or measurements to build your own reference book for your rig.

Just a thought.
 
The length of the vehicle has less effect on tail swing than the amount of vehicle that extends beyond the rear axle pivot point. The "phenomenon" is easy to illustrate with a simple piece of paper cut to a scaled dimension of the vehicle being studied. Just place a pivot pin in the center of the scaled rear axle location and move the front end through an arc while observing where the rear end goes. The farther away from the pivot pin the rear end is, the wider the tail swing. Every vehicle has tail swing. The only difference is the swing distance when turning...
 
steelmooch, does this kind of article interest you?  It appears to be a 1989 masters thesis on a computer simulation of logging trucks tracking on forest roads.  I only skimmed thru the article really fast.  It seems to me that it would be fun to adapt the information to a a motorhome/toad simulation, but whenever I start a "fun" project like this, it turns into a really time consuming pain.  https://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/26312/Ekert.pdf?sequence=1
 
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