Re: [A/S] Towing vehicle - wheelbase issue

["Mitch Hill" <fmhill@xxxxxxxxxx>]

A point of clarification, if you look at the tractor of a tractor trailer 
rig, you will see that the "coupler" is located practically over the rear 
axle of a tractor with a single rear axle, or in the case of a tractor with 
tandems, between the rear axles putting the pivot point between tractor and 
trailer as close to the turning center as possible. For this reason it is 
advantageous for semi tractors to be short as the wheelbase to coupler 
distance ratio is extremely small if there is one.  It is this short 
coupling factor that we try to achieve but never can other than with a 
fifth wheel set up which comes about as close to the handling 
characteristics of a semi.

Also, most big rig tractors are built and equipped to carry a much larger 
percentage of the load over the rear axle or axles of the tractor than a 
pickup or large car, and practice with loading a trailer is to put the 
majority of the weight ahead of the trailer axles except in a few extreme 
cases. In the case of heavy equipment haulers(lowboys), the load is pretty 
much balanced between the tractor and the trailer axles as the trailer 
axles are in the very rear behind the load.

The reason Freightliners and other heavy duty trucks are gaining popularity 
as RV tow vehicles is due to their size and weight advantage as well as 
power and they have greatly increased weight handling characteristics as 
well as longer wheelbases typically. Add to that stronger stiffer frames, 
tires that go further in mileage before being replaced, and the fact that 
most if not all big truck makers know how to make a truck very comfortable 
to sit in and drive for an 8 hour day on the road day in and day out, as 
well as truck life longevity based on millions of miles compared to the 
hundreds of thousands of the light trucks, and a truck like a Freightliner 
begins to look very practical as an RV hauler for a full timer that is 
always traveling.

--

TNX, 73, Mitch Hill - K1FH - AFA1HN