Where did you get the formula, if I may ask?
Does this formula work over a certain range? When I added my tag-along to my hitch, it added 220# or so to the rear of my truck, but did not change the front weight.
Hi Ray
To the 1st question the formula is known as calculating moments about a point. Where I got it was from my old text book, Statics and Strength of Materials by Irving Levinson printed in 1971. If you look at this post I showed Frank how I was doing this when he was working out how to figure weight and balance on his camper. Read down about 3 replies where I showed Frank this formula.
http://www.sunlineclub.com/forums/f63/homemade-travel-trailer-project-11053-2.html
Does the formula work over a certain range? Yes it works over what ever length you can dream up providing the beam or truck bed does not collapse from the length. Like a 100 foot steel beam. If the beam cannot take the loads it will buckle and give way if it is not strong enough. There are no limits to length.
John, Thanks a lot for that great info.
I don't think this will work unless I can get a plate that moves the weight forward of the axle while putting the trailer behind it. I wonder if something cantilevered would work, or if I am looking for something called "magic".
I “think” I know what you are asking but there are some issues with what you are stating/wanting. If you want to bolt a plate says 3 inches forward of the axle and then extend back behind the axle say 6” unless the plate was never touching the truck bed except for the mounting point the weight will still apply in the truck bed where ever the pin load touches the truck bed. A plate will spread it out more even but it will not shift the load up to the bolting place unless you have some real heavy beam that will not flex under it’s load and not touch the truck bed.
If you get past that, this beam also comes with a lever effect trying to rip the plate out of it’s mounting location. A 600# pin weight hanging on a 12” long lever is 600 ft lb’s of static torque into the truck bed where it is bolted. Dynamic loads may be 3 times that or more. That is a fair amount for a sheet metal truck bed. While not impossible to do into the truck frame it needs to be heavy enough and thought thru.
The real issue is while you may have moved the loaded mounting point you now have a lever effect of the pin weight behind the axle still. The lever effect is going to still trying and will lift weight up off the front of the truck. You really did not move the problem.
If the camper is 7 foot (84”) and the cab to rear axle is 39. So if you ever wanted to do 90 degrees turn you need 42” to just scrape paint. However in a travel trailer I can only turn 74 degrees before I put the propane tanks into the truck bumper. I would love to turn 90 degrees but have not yet ever in all our TT camping as I can’t.
Maybe one of our 5th wheel towing folks can say how many time they turn 90 degrees. The issue is more magnified by how far behind the front of the camper the pin is. If the pin is forward of the front wall, you can turn more then if it is a few inches behind the front wall. Ideally take a tape measure place 0 on the ball coupler and then swing the tape measure in an arc and see where the width of your truck will hit the side of the camper. That angle would be the max you can turn.
I don’t know if any of this helps, but hopefully it plants some seeds of things to think thru
Hope this helps
John
PS You mentioned you have 220# on a tag along hitch and it diod not move weight off the front end. You mean towing on a ball in the truck bumper or receiver? If so, yes you removed weight off the front of the truck and added more then 220# to the real axle. If you can give me the rear axle overhang, distance from rear axle center to tow ball, I can tell you the axle changes. Use the same formulas. The weight moved, it just maybe you did not see a large change but the fenders heights did change
