Hitch mathmatics

mdross

Member
My latest tractor JD 70 with 18.4 tires and hitch length of approx. 24" no weight up front 580lbs out back pulls the front wheels out about 60 of course pivoting the hitch down making the pull much harder and shorter. Just did a pull last night with the hitch moved in to 21" much better results. It seems I get a lot comments on moving the hitch in some say it pulls the front end sooner others say it works the opposite. Either way I'm going to try next moving it in 2 I/2" more and see what happens. Has anyone seen or know the mathematics for hitches?
 
NATPA rules say no less than 18" from center of axle. Longer would make the front come up faster I would think. 580 on the back and none on the front doesn't sound like it would work to well.
 

This is one of those "you always do this unless you think about it" things. Most guys will say that you always ALWAYS run your drawbar all the way in. But the fact is that the longer the hitch is the more leverage there is to lift your front end. Often in your lightest class you can't put enough weight on the front to hold it down so pushing your hitch in will keep your front down longer. If you are front heavy in your lightest class you can increase the down force on your tires by pulling the drawbar out.
 
The math says the shorter the drawbar the harder it is to lift the front. Real world experience tells me I used to have a 36" drawbar, never really lifted the front and never really did well.
Shortened drawbar to 20" now I need weight on the front and win.

The math is a statics equation. Pulling is dynamic.
 
(quoted from post at 04:22:45 10/01/19) The math says the shorter the drawbar the harder it is to lift the front. Real world experience tells me I used to have a 36" drawbar, never really lifted the front and never really did well.
Shortened drawbar to 20" now I need weight on the front and win.

The math is a statics equation. Pulling is dynamic.

Moresmoke, I'll bet that you go further the slower you go too.
 
Many variables play into that. Hitches tend to vary in design. How your particular hitch is set up, how it adjusts in height, height of hook point, where it pulls from on tractor body, weight etc... will all need to be considered.
 
Back at you Big Tee. Getting rain over there? Been light here all day and cold. Might start the furnace tonight. Did you check the OutLaw Pulling Forum for a video we put up? Your going to have to feed the VAC some Cheerios to keep up with the G me thinks.
 
Winter is on the way... I watched the video--Looks Good---That ol G lugs good--beating up on those little 283 Chevy V-8's with a 1000 cube G---wait until you meet up with that big cubed VAC--One of us will go home with his tail between his legs!!!!!!!!!!!!!!!!!!!---FUN...---Tee
cvphoto37955.jpg

Maybe we will put a little wager on it? Twelve pack-case? It takes a BIG dog to lead the pack..
 

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