Electrical wiring for trail hitch

Trailer hitch finally done

As I had some problem with the first trailer hitch I got, You can read about it here.

Today I got the time to put in the replacement I got and I did the exact same procedure with same kind of wax with the same procedure of application and this time there was no problem reaching the required 419 Nm. Case closed. Now I am only missing the Boler 13' trailer I have been thinking of, some day ..... some day

Bed back on chassie, atleast temporary

Bed in primer back on the chassie. Moving ALL the stuff to a different location......

But it starts to look kind of promising

Rear trailer hitch, thread failure.......sight!!!!

Rear tow hook assembly and bumper has been assembled and it´s time to mount the tow hitch threaded ball M24 according to these instructions. The state that if the thread is waxed the M24 size is needed to be mounted with 419 Nm

Rear trailer hitch brackets testfit

Got the rest of the parts back from the welder today. Wanted it done correct, by a skilled person that has a powerfull enough welder.

Rear trailer hitch, parts arrived.

This week one of the most important parts arrived from a friend that has helped me out machining it.

In the picture above I have done the last finishing touches before it´s off for welding together with the brackets. I wanted this part to be welded by a professional, just to be safe. The finsihing touches was some small fillets on the edges and a chamfer on the hole so that the ball stud could fit correct.

I actually did a lot of FEM simulation to get this part as strong as possible. As you can see the inner radius is actually not a radius, but an elips, this distributes the loads onto a larges volume witch decreases the stress levels on the inner radius.  

Strength calculations, Rear trailer hitch

I have had some plans on building my own tow hitch and according to SFRO (Svenska fordonsförares riksorganisation) an organisation that controls home build vehicles in close cooperation with the Swedish authorites here i Sweden, I am allowed to build my own tow hitch rated for the maximum totalweight of 1500 kg (3307 lbs). I guess thats close to a class 3 tow hitch that has a 3500 lbs gross trailer weight.
I am not enforced to make a calculation of the tow hitch, but if the inspectors belive it "Looks weak" I am obliged to show a calculations, that shows the tow hitch fullfilles the requirements stated further down in this post.
So has I have the knowledge and the tools why not make a calculation and see what is says??

Rear Trailer hitch and bumper bracket design

This started out in this post

Now I have done some designing to make a bracket system that reminds of the stock one as much as possible, but still hides as much as possible of the trailer hitch support beams.

Rear trailer hitch/bumper brackets, start

I have made some plans to replace my old farm bumper with a new stock reproduced rear bumper, together with a tow hook. The tow hook I have choosen is this:

It´s made by monoflex and the partnumber is 50.03. The D-value is 17.17 kN and the corresponding D-value for my truck (total weight 2270kg) together with 1500 kg maximum trailer weight gives a D-value of 8.83 witch is well below the 17.17 for the tow hook. It´s a 50 mm tow hook with a M24 thread and costs 280 Sek. The hook is granted for 3500 kg.

Here is the mounting instructions:

Tonight I also took some measurement for the brackets. Will make some cad drawings for these that will show up here eventually.