[VACList] hitch analysis

[Warren Little <wlittle@xxxxxxxxx>]

After seeing the recent posts on weight distributing hitches I thought I
would try analyzing my rig that uses a Reese dual cam hitch. My truck is
a F250 long box supercab and my trailer is a 76 31 ft. Sovereign. 

I considered a simple free body model for the truck and trailer, wrote
the force and torque equations and evaluated them using Excel. I assumed
the truck weighed 5000 lbs and the trailer 7000 lbs. I measured all the
relevant distances on the rig and further assumed the center of mass of
the truck was half way between the front and back wheels and the center
of mass of the trailer was 1 ft in front of the center of the trailer
wheels.

The results for chain tensions varying from 0 to 2000 lbs are shown in
the table below. 


truck	trailer	chain	ball 	trailer	truck	truck
weight	weight	tension	weight	wheels	front	rear
					wheels	wheels
fw	fa	fc	fb	ft	ff	fr
5000	7000	0	368	6632	2374	2994
5000	7000	200	547	6653	2412	2935
5000	7000	400	726	6674	2449	2877
5000	7000	600	905	6695	2487	2818
5000	7000	800	1084	6716	2524	2760
5000	7000	1000	1263	6737	2562	2701
5000	7000	1200	1442	6758	2599	2643
5000	7000	1400	1621	6779	2637	2584
5000	7000	1600	1800	6800	2674	2526
5000	7000	1800	1979	6821	2712	2467
5000	7000	2000	2158	6842	2749	2409

Note that as chain tension increases the weight on the truck front
wheels and the trailer wheels increases but the weight on the truck rear
wheels decreases. I was surprised to see the ball weight increase as
much as it did.

I hope somebody might find this interesting.

Warren Little #9302