Receiver hitch

[terrawombat]

I bent it!

 

[87Warrior]

That is cool!

 

I am sure you will run a few more studies with different forces. I think forward and backward forces would more realistic.

None the less, I figured the weak point would be where the brackets meet the square tubing. That demonstration proved me wrong!

[terrawombat]

The highest stresses occur around the bolt hole furthest towards the rear of the truck. The above screenshot shows deflection and I turned the "deformation" factor up WAY high because it looked goofy. The actual total maximum deformation is less than a tenth of an inch. I just did a static load of 1200 lb. on the tongue, which is the maximum recommended tongue weight for a Class IV hitch (this is designed to mimic a Class III hitch). Even with that loading, the maximum stresses were well under the yield stress for A36 steel. I'll run some more simulations when I get home and I'm actually near a computer with a 23" monitor, rather than on this 10" netbook riding in a car!

[Walkenvol]

If I understand your model and its correct, then the weak point is the 2" tubing which I thought was standard in the trailer hitches I've seen? Is it worth beefing up the 2" tubing or does this prove the hitch design is as strong as others sold in the market place?

 

I figured the weak point would show to be sideways pulling since the flat metal brackets don't have any gussets. I have seen some sold where the flat brackets had about a 1/2" bend on the bottom edge.

[terrawombat]

If I understand your model and its correct, then the weak point is the 2" tubing which I thought was standard in the trailer hitches I've seen? Is it worth beefing up the 2" tubing or does this prove the hitch design is as strong as others sold in the market place?

 

I figured the weak point would show to be sideways pulling since the flat metal brackets don't have any gussets. I have seen some sold where the flat brackets had about a 1/2" bend on the bottom edge.

 

The screenshot shows displacement, which is not necessarily a determination of a weak point, persay. It makes sense that the largest displacement in the model occurs directly in the middle. You won't see large displacements at the bolt holes because they are a pinned constraint and aren't allowed to move in the model. I have a lot of refinement that needs to be done to provide a much more realistic model and it's been a while since I've used this particular finite element modeling software, so I need a refresh my memory of all of its capabilities. I just wanted to throw something up so you can see how I'm doing my preliminary "testing" of the brackets.

 

Ideally, what I'd like to do is insert a ball receiver into my model and place the artificial trailer loading on the ball itself. Due to the increased length of the ball receiver the hitch will have a greater tendency to want to "twist" and should show a change in the stress concentrations in the model.

[jimoshel]

I think your over testing, but nothing wrong with that. I have had two personal experiences where bad things happened while pulling a trailer. Once pulling a double axle UHaul from Wi. to Co. In the middle of Iowa the trailer began whipping and flipped over on it's side, pulling the back of the truck up off the ground by the safety chains. The trailer tongue separated off the ball. The hitch was undamaged. No 2 I was pulling a Jeep S/W with a tow bar when the right front tire on the Jeep blew. It began whipping and finally went off the side off the highway rolling both vehicles 2 and a half times, totaling both vehicles. The tow bar was destroyed. The hitch was undamaged. Just for what it's worth. Your doing a great job on this project. Every body appreciates it. Jim

[Sir Sam]

I bent it!

 

 

Ya, you know an engineer when you see one:

 

 

 

When I was building the motor mounts for the CRD swap I whipped up a little ProE and did a failure analysis.

 

I looked at it a 50MPH impact to a dead stop.......motor mounts held up fine. :thumbsup:

[terrawombat]

Good 'ole Von Mises.

 

I fired up the built-in FEM in SolidWorks for the first time in years this morning. I had to LOL at how much faster and easier it is to program a finite element model than it is to do a CFD model with combustion. There's another fellow in my office that does all of our finite element modeling and I'm no longer going to feel sorry for him when he runs into a problem with something. I literally spend a week getting a CFD model to run right on an expensive computer set up for it. I had an answer with this receiver hitch in less than three minutes on my netbook.

[Sir Sam]

Good 'ole Von Mises.

 

I fired up the built-in FEM in SolidWorks for the first time in years this morning. I had to LOL at how much faster and easier it is to program a finite element model than it is to do a CFD model with combustion. There's another fellow in my office that does all of our finite element modeling and I'm no longer going to feel sorry for him when he runs into a problem with something. I literally spend a week getting a CFD model to run right on an expensive computer set up for it. I had an answer with this receiver hitch in less than three minutes on my netbook.

 

No Kidding. FEA is cake compared to CFD modeling, worst I ever run into with FEA is me giving up on the model and starting over again.

[JACKED88]

 

Now, thinking about this from a production standpoint - it would be cheapest and, for me, easiest if I provided the bare cut side plates and safety chain plate and then the buyer bought the 2" square tubing, angle iron, and hitch receiver tube. I would obviously have to put a giant disclaimer on the plates stating that they are in no way rated for any load whatsoever.

I wouldn't have expected it any other way. The "buyer" should be able to find square tubing at just about any steel supplier. Problem is most suppliers only sell it in 20 foot sections. I don't know any that sell it by the foot. Most of um will cut it for you for a minimal cost but your still gonna have to purchase the whole 20 foot pc. Best thing is to find a couple of other people who want to build a hitch and split the cost of the tubing. That or find a manufacturer or welding shop that uses/has 2" tubing and buy a 4 1/2 foot pc from them. (4 feet for the cross pc and 6 inches for the receiver) Plus, a 10 inch long pc of 2"x3" angle iron.

Keep in mind that not just ant square tubing will do. It will have to have the correct wall thickness so your receiver fits properly. I'm pretty sure it needs to have 1/8" wall thickness. Take your receiver with you for proper fit.

 

Sorry but I was mistaken in what I said about the safety chain holes being in the pc of angle iron that welds to and or between the cross pc and the receiver. The angle iron pc has holes in it so you can bolt the hitch to the bottom side of your bumper. The safety chain restraints/holes are separate from that and could be simply made out of two heavy chain links/u-bolts/I-bolts or whatever welded to the bottom side of the receiver section.

 

As before, I'd suggest people go to their local welding shops to pick up small sections/pcs of iron. You'll need 1- 4 foot pc of 2 inch square tubing, 1- 6 inch pc of 2 inch square tubing and one 10 inch pc of 2x3 inch angle iron. Plus some kind of rings for your safety chains to hook to.

[terrawombat]

I forgot to verify this on the Draw-tite hitch that I have, but I think that the long box tube cross piece is 2.5" square tubing. I know that the receiver tubing is definitely 2" square tubing, but I need to verify the wall thickness of that.

[Sir Sam]

Problem is most suppliers only sell it in 20 foot sections.

 

My local place sells by the foot, cut charge too.

[terrawombat]

Problem is most suppliers only sell it in 20 foot sections.

 

My local place sells by the foot, cut charge too.

 

Yea, I've got a couple places by me that do per foot too. But, it's always cheaper per foot if you buy the entire 20' piece. Problem is that 20 feet of steel doesn't fit too well on any of the trucks I have :D

[JACKED88]

I forgot to verify this on the Draw-tite hitch that I have, but I think that the long box tube cross piece is 2.5" square tubing. I know that the receiver tubing is definitely 2" square tubing, but I need to verify the wall thickness of that.

Your right. The cross pc is 2.5 inch O/D tubing. The "female" part of the receiver is also 2.5 O/D tubing with 1/4 inch wall thickness. The "male" part of the receiver (part with the ball) is 2 inch O/D tubing.

 

You guys are lucky to have places you can buy material by the foot. I've been buying material for years and have yet to find a place that'll do it. Every now and then they'll have cut pcs but seldom are they what I'm looking for.

[terrawombat]

I forgot to verify this on the Draw-tite hitch that I have, but I think that the long box tube cross piece is 2.5" square tubing. I know that the receiver tubing is definitely 2" square tubing, but I need to verify the wall thickness of that.

Your right. The cross pc is 2.5 inch O/D tubing. The "female" part of the receiver is also 2.5 O/D tubing with 1/4 inch wall thickness. The "male" part of the receiver (part with the ball) is 2 inch O/D tubing.

 

Interesting information. I'll have to check my hitch out, but I was very confident that the female portion of the receiver was 2"OD. I was also measuring an XJ Class II hitch last week so I may have my dimensions mixed up.

[JACKED88]

I forgot to verify this on the Draw-tite hitch that I have, but I think that the long box tube cross piece is 2.5" square tubing. I know that the receiver tubing is definitely 2" square tubing, but I need to verify the wall thickness of that.

Your right. The cross pc is 2.5 inch O/D tubing. The "female" part of the receiver is also 2.5 O/D tubing with 1/4 inch wall thickness. The "male" part of the receiver (part with the ball) is 2 inch O/D tubing.

 

Interesting information. I'll have to check my hitch out, but I was very confident that the female portion of the receiver was 2"OD. I was also measuring an XJ Class II hitch last week so I may have my dimensions mixed up.

To be certain I just went outside and measured one of the store bought receivers I have. (the male pc with the ball) Is is definitely 2 inch O/D material with 3/16 wall thickness. I also remeasured 2 of the three hitches on my other vehicles and both "female" receivers are 2.5 inch material with 1/4 inch wall thickness.

The wall thickness and or I/D of square tubing is never exact. The walls are usually a little thinner than 1/4" making the I/D a little larger. That's why a 2" O/D ps of material will easily fit into a 2 1/2 inch O/D pc having 1/4 inch wall thicknesses. The over all difference is usually about .040 and often a little more pending the manufacturer. Hence the reason all "male" receivers fit loosely into the "females" (yes, we're still talking about trailer hitches) LOL!!!

[terrawombat]

Hence the reason all "male" receivers fit rather loosely into the "females" (yes, we're still talking about trailer hitches) LOL!!!

 

So it that because the female is too big or the male is too small?

 

This is actually a good thing as it makes it much easier to buy the tubing stock. Just get 2.5"OD square tube with 1/4" wall thickness for the cross piece and the female receiver tube and call it done.

[JACKED88]

Hence the reason all "male" receivers fit rather loosely into the "females" (yes, we're still talking about trailer hitches) LOL!!!

 

So it that because the female is too big or the male is too small?

 

This is actually a good thing as it makes it much easier to buy the tubing stock. Just get 2.5"OD square tube with 1/4" wall thickness for the cross piece and the female receiver tube and call it done.

The female is too big meaning the male is right .... for once. LOL!!!

 

Yes, the same pc of material can be used for both. 1/4 inch material for the cross pc would definitely be heavy duty. Most hitches/cross pcs are made out of thinner 3/16 inch material.

 

With the use of 1/4" thick brackets, additional mounting holes and 1/4" wall tubing for the cross pc, if welded properly these hitches should exceed the rated capacity of a DrawTite or any other hitch that was manufactured for our trucks. If anything was to fail it'll likely be the "buyers" welding. Hence it being perfectly understandable expressing your disclaimer of liability for damages caused by using these brackets to build a trailer hitch.

[JACKED88]

TerraWombat, it's been a while so I was wondering what the latest is on those brackets? Any progress on getting your shop/machines set up to run a limited production of um?

[terrawombat]

TerraWombat, it's been a while so I was wondering what the latest is on those brackets? Any progress on getting your shop/machines set up to run a limited production of um?

 

Next month. I am going part-time and eventually being replaced at my current job (by choice). Without a steady influx of income, I'm gonna need something to pay the bills :)

[JACKED88]

TerraWombat, it's been a while so I was wondering what the latest is on those brackets? Any progress on getting your shop/machines set up to run a limited production of um?

 

Next month. I am going part-time and eventually being replaced at my current job (by choice). Without a steady influx of income, I'm gonna need something to pay the bills :)

Sounds great. Keep us posted.

[Walkenvol]

Problem is that 20 feet of steel doesn't fit too well on any of the trucks I have :D

 

18 vlt sawzall in the parking lot works for me.

[Zieg]

Another guy who needs to get in on this kit. I found a mj named Anasazi. Then I found a cap and a bumper! Then I got rear-ended by a car that was rear ended by a car full of teen-age girls. Now I've got to make a bumper and a hitch. Aw well,I didn't have anything else to do.

[mphjeep]

Hello,

I've been checking this site out for a couple years and I'm totally addicted to this post. Has anyone heard of news on being able to buy the side plates. I'm very, very interested in getting a set.

[terrawombat]

Unfortunately, I'm not going to be able to make it happen. I simply do not have the time or resources to make it happen. I will also be making a move to Maryland in the near future and the CNC plasma machine will not be coming with me until I get myself a house with a very large garage.