Need some design help

[bgott]

Would something like an old joedog or jiflock with a wrecker sling and an electric winch powered off the towed vehicle work?

 

[Anonymous Poster]

Naw Gary, no diagram, all I got is a bunch of pretty colored magic markers. I was hopein somebody with a CAD program might fill in the lines in the coloring book.

Another thought that occurs to me, you might want to check with your insurance carrier to see if the deal would be conered. In NY, when you back under a trailer the tractor is insured by the trailer. The state DOT boys frown mightily on the Sooner Boomers for towing cause the towing tractor isn't really insured.
This whole deal would be a lot easier if you just use a chase car with a manual transmission and a conventional tow bar.

 

[Gary_in_Indiana]

That's a good point regarding the insurance and my insurance agent has assured me I'm OK with towing MY vehicles on MY equipment (dolly or trailer) behind MY vehicle. While typically those situations involve towing a trailer or dolly to pick up something I've bought then towing the newly purchase vehicle back I can't see where it would matter which is towing which.

As to using a manual transmission tow vehicle with a tow bar I'd still have to attach the tow bar to something which would still involve getting some attachment point established on the semi.

 

[Gary_in_Indiana]

Bgott,

I'm not familiar with how those work. Would that preclude me from using different chase vehicles?

 

[bgott]

Both of those were converters used to convert a two axle tractor to a three axle. The joedog was basically a converter dolly with a fifth wheel on it and a fifth wheel pin. Clear as mud, right? It would swing when you went around a corner. The jiflock (sp?) was a system, it had sockets that went on the ends of the frame rails that the dolly butted into to keep it from swinging. I'm originally from California, I don't know what they called them in the east. I figure you could convert one if you could find it or build something along those lines and rig it for a gooseneck pole for when it was behind the tow vehicle. You would be limited to a gooseneck equipped tow vehicle. Unless you put a regular hitch on the end and then used a tongue jack that would lift it high enough to back the tractor under. I know people that use a sling set up on an axle with a regular trailer tongue all day long around here to haul cars, all you would be doing is adding an extention to be able to hook it on the fifth wheel. I know one guy who's sling rig might be available for pictures sometime next week. It's, shall we say, lacking polish but would give us a start on designing something.

 

[Gary_in_Indiana]

Harv,

I don't think it's me so much as the different manufacturers and different configurations making this difficult, honestly. /w3tcompact/icons/shocked.gif

Today I went out to North American/Allied/Global Van Lines headquarters here and looked at a number of different year/make/model trucks there at their tractor shop facility. The most common thing was the lack of a common design. On almost every truck I saw a way to make something for the frame rails that would work. Unfortunately, I didn't see a way to make anything that would work on all of them other than a fifth wheel tongue assembly. /w3tcompact/icons/hmm.gif

The frame rail attachment that would work on one wouldn't on the next. What would work on that one wouldn't work on the last one, etc. While there is a commonality of the frame rails there is no commonality as to what is attached where on those frame rails. /w3tcompact/icons/crazy.gif

There are air bags, lights, wiring, bolts, etc., that can interfere with the connection points on the flange I would need to use a flange attachment hitch. I never fully appreciated all the different configurations of equipment until I started on this quest. /w3tcompact/icons/shocked.gif

It looks like I may have to go with the fifth wheel tongue assembly back to a ball mount in order to have something that'll work with everything. If I do, I'm concerned with the 90 degree drop down piece at the back end of the fifth wheel tongue folding under during an emergency stop. What size tubing and sidewalls should I use for this? Should the 90 degree corners be mitered or butt jointed? Is there anything else I should consider?

I spoke to a buddy of mine in Chicago who told me he's seen some type of hitch assemblies either clamped or chained onto the semi tractors being delivered to his store there that tow cars behind for the driver's return trip. He's going to get me some pictures of different ones as they come in for deliveries. Maybe I'm just more concerned with being extra safe and that's the problem. /w3tcompact/icons/wink.gif

Thanks for all your input and advice on this. /w3tcompact/icons/smile.gif

 

[bgott]

http://www.grantgoreandsons.com/item5.htm

The website above has a picture that can be used as a starting point for what I'm trying to explain. Lose the second axle, go with smaller wheels and tires, add a ball hitch or gooseneck post on the hitch end past the pin and then add a wrecker sling to what's left.

 

[Gary_in_Indiana]

What you're describing would essentially be a fifth wheel tow dolly. I'm sure it would work but am really not interested in (spelled 'capable of') building a fifth wheel dolly from scratch. I already have one dolly so I don't really want to build another one, either.

 

[hazmat]

Gary,

Looks like I may be a bit busier at work today so the pretty pictures will have to wait.

As far as the 90 degree corner buckling under braking, I would gusset the corner. Simply weld a triangular plate on each side. This makes a HUGE difference as far as strength is concerned.

Mitred gives you more length of weld, but the "but" joint is simpler to construct. With the gusset, you will have plenty more space to weld.

 

[Gary_in_Indiana]

Will 2" square tubing with 1/4" walls be heavy enough to handle what I'm looking to do here? I know I'd have to use 2 1/2" tubing for the 'over' portion of the sliding extensions and then drill, right? Also, how much do I need to leave in the tube at maximum extension to maintain strength and stability? Lastly (well, we can hope /w3tcompact/icons/smile.gif ), what size and how many (one or two) pins should I use to secure the extensions?

 

[Anonymous Poster]

2" square with 1/4 walls will be more than sufficient to your task. Reese uses the same material, and the forces on those hitches can reach 15000#.
A 12" overlap will be more than sufficient as long as the tubes are relatively a tight fitup.
The only thought I have to add, assuming your'e using desing 27.6.R would be to goosneck the toung to the 5th to insure sufficient clearance over the tail of the tractor going over speedbumps and knolls.
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This diagram looked perfect when I did it, it's the board's fauylt

 

[Gary_in_Indiana]

My concern was that from the crossmember I'll be attaching to the top flange of the frame rails I'll be coming back around 18" then coming down about 30" to the ball mount all without any lateral support whatsoever. That just seemed like a long way for 2" tube stock to go with no lateral support.

I agree that Reese uses the same stock but I don't think they go anywhere near that distance with it. As to speedbumps, etc., I think the ball and coupler will more than handle that. I want the fifth wheel hitch assembly to be as stable as possible.

I'm sure I'll get some good input and CAD diagrams on this yet. I'm hoping WHarv can give me something definitive on the material I need (hint, hint /w3tcompact/icons/smile.gif ). Thanks a bunch for all the help thus far everyone. You'll likely never really know how much I really appreciate it. /w3tcompact/icons/smile.gif

 

[Anonymous Poster]

Shoot Gary, I got the model #s mixed up. I thought you were just going to extend the toung of the dolly.
I checked a dolly today, and that toung is only 3x3x1/8 tube.
On the 30" drop, I'd probably go with 4x4 tube, and pierce thru it with a piece of 2.5" at the top to tie it into the piece of 2" square coming back from the 5th wheel. That would give you more flexibility in terms of the distance from the 5th pin back to the hitch vertical member.
Reese uses 2x2 for cross members on a lot of hitches, and many of them span almost 4 feet, and carry a lot of torque on the cross member. Unless you're talking about something like a Humvee as a chase car, I don't think it would be a problem. I also think you may be a tad off on the 36" drop, seems to me the tail ends of most tractors nail me between the knee and hip when I walk too close behind one in the dark, but I don't have a bruise available for measurement right now.

 

[Gary_in_Indiana]

<font color=blue>"I also think you may be a tad off on the 36" drop"</font color=blue>

Franz,

I'd estimate the drop around thirty inches. Typical fifth wheel height is 48 inches and typical ball mount height is eighteen inches. I'd rather have something that will work with thirty inches and only need it to work with a few inches less than overtax something.

I'm not surprised at the tongue material for a dolly being as light as it is. There is virtually no tongue weight involved as those dollies are very well balanced. I've actually lifted the tongue of a loaded dolly to unmount it from one tow vehicle and put it on the ball of another one.

I'd be concerned about welding an upright piece to that material for a fifth wheel mount. I think it could be too much stress for the dolly tongue itself in an emergency braking situation.

 

[hazmat]

<font color=blue>I'm not surprised at the tongue material for a dolly being as light as it is. There is virtually no tongue weight involved as those dollies are very well balanced. I've actually lifted the tongue of a loaded dolly to unmount it from one tow vehicle and put it on the ball of another one. </font color=blue>

Gary,

Does the fifth wheel need a min amount of tongue weight to keep it together ? (I'm not familiar with them)


<font color=blue>I'd be concerned about welding an upright piece to that material for a fifth wheel mount. I think it could be too much stress for the dolly tongue itself in an emergency braking situation.

</font color=blue>

Maybe the trailer (not dolley) design is a sturdier option. you could make the fifth wheel hitch as beefy as you want to be comfortable that it will withstand the braking forces.

 

[Gary_in_Indiana]

There's no minimum tongue weight to keep a kingpin in a fifth wheel. The kingpin design keeps it from coming 'up' out of the fifth wheel and the locking mechanism of the fifth wheel keeps the kingpin from coming 'back' out of the fifth wheel.

I know a fifth wheel trailer would be a slick deal but that would mean always sendig a full size truck with a fifth wheel to haul it. That gets pretty expensive and proprietary for me, I'm afraid. /w3tcompact/icons/frown.gif

 

[hazmat]

Gary,

Sorry it took a while to get back on this thread, it got burried on TBN.

As far as tubing sizes go, poke around a trailer dealer a bit. (not a semi trailer dealer, but someone who has conventional car trailers, tag a longs & fifth wheel or goosenecks). Check out the fifth wheel & gooseneck trailers. That will give you a reference point to size your tubing.

You'd be amazed at how accurate your eye is at judging strength of a design. 2" tubing looks a little puny to me. If it don't look right to you, you will be nervous driving it. 'nuff said.

<font color=blue>There's no minimum tongue weight to keep a kingpin in a fifth wheel.</font color=blue>

In that case, go for modifying the car dolley. I still vote for making it semi-permanently mounted on the dolley and swing it around to attach to the semi-tractor. I think once you size your tubing, you may not want to break down/ set up the "tongue".

I say semi permanent because you may want to use the dolley in the conventional manner. I'm assuming you have some kind of lift to take it off at your shop. You could always use your FEL/w3tcompact/icons/grin.gif

Let me know if we can be of any help.

 

[Gary_in_Indiana]

I talked with a manufacturer of a dolly who told me the main structure onto which the wheels are mounted is 4" x 4" x 1/4" steel tubing. Armed with that knowledge, the latest incarnation of this plan is to see if I can get them to build me one using that material as stock for the tongue as well. The standard tongue has two bends in it which would need to be replicated. One brings the tongue up from under the front bumper of the towed vehicle up to hitch height and the other goes from that angled section forward to the coupler level parallel with the ground. I'd have to accomplish those two angles by cutting and welding the tube stock.

The stock weighs approximately 1.1 lbs. per linear inch. I'll be adding approximately sixty pounds to the weight of the bare tongue this way. I'd also want to add 12"-18" upright piece near the coupler over which my fifth wheel tongue will attach. That would bring the additional weight to around eighty pounds higher. With that much of a weight addition I'll add a trailer jack.

I'm thinking the 'removable' portion might have to be in as many as three pieces because of the weight. One would come up from the fixed upright on the dolly tongue and include the 90 degree corner and gussets there. Another would have the kingpin and plate for the fifth wheel while a third would be a straight piece connecting the other two and by which length adjustments could be made. I might be able to eliminate this piece and just lengthen the other two if they don't get too heavy.

While I agree I may not want to breakdown/set up the fifth wheel tongue, I don't see how I'll have much of a choice. I can't have the driver tow the dolly with the fifth wheel tongue and kingpin/plate above the car so it has to be able to be turned around to allow it to be towed to the truck. Even if it would be high enough to clear the car top turning a corner would put the kingpin in the other lane (and possibly into someone else's windshield or through their grille). /w3tcompact/icons/hmm.gif

Assuming I've explained the above well enough, please give me your opinion or any other ideas on the plans. Thanks. /w3tcompact/icons/smile.gif

 

[hazmat]

<font color=blue>While I agree I may not want to breakdown/set up the fifth wheel tongue, I don't see how I'll have much of a choice. I can't have the driver tow the dolly with the fifth wheel tongue and kingpin/plate above the car so it has to be able to be turned around to allow it to be towed to the truck. Even if it would be high enough to clear the car top turning a corner would put the kingpin in the other lane (and possibly into someone else's windshield or through their grille). </font color=blue>

Gary,

I think you may be able to tow it with the rotating tongue & not hit other cars. See attached pictures. I made some assumptions on dimensions, please correct me if they are wrong.

Dolley w/ tongue in stowed position

 

[hazmat]

Dolley w/ tongue in towing position.

Here's the procedure for hooking up the semi tractor.

Park dolley in accessable area.

Jack up with tongue jack

Swing fifth wheel tongue around.

Back semi trailer under tongue

lower tongue jack.