Built me a towbar

[m16ty]

After pricing military towbars and getting tired of having to borrow one every time I needed to tow I decided to build one. With work being slow I may offer them for sale if I can bulid them reasonably priced and there is interest. I'm a little worried about the liablitiy though.

Tested it today and everything worked fine . It's sitting in the shop today with a fresh coat of OD drying.

I already see some mods I need to make to work better. If I start building them I've got a freind that can cut all the pieces on a water-jet to make a more professional job and I will weld them together.

 

[scooter01922]

Looks good, i have been contemplating doing the same. Know a guy with a CNC milling machine and a lot of down time right now. Prob be happy to have something to do for short cash. What type of tube did you use for the legs? When you get a price structure figured out be sure to post it up, if i haven't figured something out by then i might be interested.

 

[wreckerman893]

If you can bring them in for around $250.00 you will prob do a land office business.

I would be interested since my tow bar dissapeared from a former members shop.

 

[dm22630]

How much?

If those that bought them signed a form/paper accepting full responsibility for use, and that they would be used for "off road/low speed only", I would sell them if I were you.

oh yeah....how much!?

 

[OD_Coyote]

I may be interested too, depending on price.
With three deuces in the family, you never know when a towbar might come in handy.

 

[m16ty]

I haven't got a firm price yet. I'm working on it.

The legs are 2X2 1/4" wall square tubing. I had some pipe the same size as a mil. towbar but the tubing was easier to work with. I'm going to do some more testing and if anybody sees a problem with design or anything, by all means, speak up. I thought about adding a "third leg" that attaches to one of the main legs and swings to the ground to support the towbar at the correct height while hitching ( if you've ever tried to hook one up by yourself you'll know what I mean).

 

[MilitaryRestoration]

OD... i've got authentic ones with 1" ends if you are interested pm me... and anyone else for that matter

 

[OD_Coyote]

OD... i've got authentic ones with 1" ends if you are interested pm me... and anyone else for that matter

PM sent.

 

[dm22630]

OD... i've got authentic ones with 1" ends if you are interested pm me... and anyone else for that matter

PM sent!

 

[Lonesome715]

I to might be interested in a tow bar. We are in kind of a hurry though. How soon do you think you will start producing them?

 

[YankeeDuece]

Low price and low weight, sounds like a great idea!

 

[halftrack]

Did you do the calcs to make sure you have enough enough on the circle end to prevent a tear out? It looks like you used plate which is not nearly as strong as a "forged" end. Just thinking of safety.

 

[m16ty]

Did you do the calcs to make sure you have enough enough on the circle end to prevent a tear out? It looks like you used plate which is not nearly as strong as a "forged" end. Just thinking of safety.

I agree about it not being as big but I think it's ok. It's cut out of 5/8" plate ( I thought about using 3/4" plate but was trying to keep the weight down). I sill may go with 3/4 on the production ones. I'm no engineer by no means but I've built lifting equipment to handle loads in excess of 40,000lbs. so I kind of know what it takes. I think the accual weak link in the system is where the factory lugs bolt onto the truck with 1/2" bolts.

I've got a forklift that weighs 34,000lb. on the back axle and a forklift that will pick 40,000#. If I sell them I'm going to do a demo where I'll pic up the rear of the forklift (34,000lbs.) with the towbar. That's almost double the weight of even a 5-ton cargo and I have no doubt it will do it but will test just to make sure.

I could have the whole thing engineered but that's just going to run the price up.

 

[cbvet]

Good idea, but I question the strength. There is a huge difference between the ability to simply lift a lot of weight, & the ability to tow a lot of weight while it is twisting & turning.
Eric
CBVET

 

[jimm1009]

tow bar

I'm not and engineer but I have a suttle comment.

Wouldn't round 4130 tubing be better than square tube?

Not trying to put down anyones work here just and only a question.

Any engineers out there???????????

4130 is what all the old tubular aircraft frames were made of.

I understand that it is a challenge to weld but strong as he!! when completed.

Jim

 

[Djfreema]

Good looking towbar. They are an added piece of mind in case of a breakdown, you can call a friend instead of an expensive tow company. It will more than pay for itself after the first use. You can cut out a couple of pieces of steel in a smaller diameter on the lunette and weld them on each side for added strength if your worried about it, kind of like the member here that built his own towbar and had about 5 pieces of steel that he welded together then ground down and it looked like the factory forged towbar lunette, as shown in this thread. http://www.steelsoldiers.com/showthread.php?t=21184&highlight=towbar

 

[colomil]

I like your towbar design. Have you considered using an off the shelf lunette? Uhaul has them: http://store.uhaul.com/Heavy-duty_towing/Moving/Lunette_Eye_with_Threaded_Shank

I am a mechanical engineer so I can run some static strength calcs for ya if needed. If you were to get serious about building these towbars in volume, I would suggest getting it drawn up in Pro-E or AutoCad and run the stress/strain calcs.

 

[colomil]

Here are some quick rough calculations:
Yeild strength of each 2"X2"X0.25" A36 mild steel leg= 36,300 PSI X cross section area (.9375) = 34,031 PSI. Take this number times 2 to account for the other leg. These numbers seem big but I would consider this the minimum strength. When turning corners, the towbar will be subject to compression load on one leg and tension on the other and I would bet this it the most stress the tension leg would encounter.

4130 tube would be much stronger for the same weight, but will cost more. Run the same calculations using 4130's 63,100 PSI yeild strength and you will see how much stronger it is. Welding & cutting would need to be done a little more carefully as well.

 

[msmith304]

I'd buy one

 

[m16ty]

Good idea, but I question the strength. There is a huge difference between the ability to simply lift a lot of weight, & the ability to tow a lot of weight will it is twisting & turning.
Eric
CBVET

When I first pulled out on the road from a gravel parking lot durring the test tow the towed truck didn't staighten back out and the tires cut all one way jerking the back end of the towing truck around and then started dragging the front end. Other than a bad wreck I'd say this is about tops on stress level when pulling another deuce. After I got going on pavement it towed fine though.