Geometry question - can I make this turn?

[ctann]

Hi all,

Still yet to buy my new trailer, but I am trying to decide just what length I can go with. I have a tight turn across a bridge to get into my property, and I have seen people get stuck (or run up the curb and damage the bridge) trying to make the turn.

Of course, the one way to answer my question is to "try it out" - but I don't want to buy a 35' trailer and tow it to the bridge, only to get stuck!

So, the geometry is
- Making a left hand turn from a road onto a bridge
- Road is 34' wide, and I can get all the way over to the right before starting the turn
- bridge is 12' wide.
- My tow vehicle is an LWB F350 with a 28' turning radius.

I have made the turn with a 23' trailer with absolutely no problem. Now I am stepping up in trailer size - and I want to figure out just how long a trailer I can stretch to without getting stuck. I am hoping 30' will be OK, but I just *love* the layout of the 35' trailers, so I am getting greedy! 🙂

So I am going to go shopping, and hopefully they will let me "test-drive" - I'll set up some cones in a parking lot, and see if I can make the turn. Still, I would like some idea beforehand of what length I can go up to. Anyone have any advice?

Cheers,
Chris.

[tatest]

I would build a scale model of the road and drive situation, and try scale models of the trailer geometries for those that interest me. Critical are ball to axle, axle to bumper, and for fivers, the pin location vs clearance to rear of truck cab. Pay attention to location of obstacles, there are usually things off the side of the road to hit.

[ktmrfs]

well, I had an occasion where I had to make a right turn from a two lane highway (90 degree) onto a 9' wide bridge that was just about 10' off the road shoulder. I'm towing a 35' trailer with a overall length of 65'.

Buddy said, sure you can make it. Well, I did, but only by going onto the oncoming traffic lane shoulder and making the turn. at the other end I had about 25' in front of the bridge to make a right turn after that. (or hit a row of trees.) I did it. the problem was getting back out. took lots of jockying to get the trailer lined up straight to go across the bridge. bridge had 4' high guard rail extending to the end of the bridge. that was the biggest issue.

[ctann]

Just a quick wrap-up to this post. I took the measurements of the turn, and before purchasing the trailer, the dealer was kind enough to let me mark out the turn in the road behind his lot, and practice the turn. It all looked good, so the purchase was made!

On the big day - no problems at all - cleared the turn with a good 6 inches to spare. Going with a much longer trailer would probably have been a problem, but as it is, looks like 35' is the perfect size.

Thanks to all for the advice, from one happy camper! 🙂

Chris.

[badercubed]

What is on the right side of the road? Tail swing might not be an issue.

This is all I can think of...

https://www.youtube.com/watch?v=qDxVJ471hyg

[wnjj]

ctann wrote:
With respect to 5th wheels - I thought that they would actually "cut the corner" more than a regular trailer?

They do but you can overshoot so the trailer wheels are close to the bridge and then back up the tow vehicle and jackknife much tighter until you can cut the front onto the bridge pulling forward.

[gijoecam]

My gut-feeling without any fancy drawings or calculations (yeah, I'm jealous!) is that the new trailer is 7 feet longer than the old one. Assuming the same relative proportions, this means there will be roughly three to four feet more tongue length on the trailer (i.e. the distance from the ball to the axles). My gut-feeling is that if the old trailer wasn't an issue, the additional four feet of tongue length on the trailer shouldn't be an issue either. Swing a couple feet farther and cut the wheel faster, and that should work fine.

Good luck!

[Krease]

Pictures would be helpful too. Of turn and bridge.

[ctann]

Thanks for all the replies. I had been concentrating on everything in front of the trailer axles, and hadn't considered the rear swing - very important point!

I am going to take the suggestion of trying this out in a car park. Actually one thing that has bugged me in my whole research project is that the manufacturers never show the exact location of the axles on their floorplans - would make such calculations much easier! I am guessing that a 30' trailer is ~= 20' to the rear axle, and 10' tail, and a 36' would be 24' and 12'. Does that sound about right? Or do the longer trailers grow the tail rather than just pushing the axles further back?

With respect to 5th wheels - I thought that they would actually "cut the corner" more than a regular trailer? I saw a 5th wheel stuck on this bridge - but I think that was the driver's fault, as he was trying to maneuver on the bridge and wound up breaking his transmission!

Anyway, enough over-alaysis on my part - need to get out in the real world and try this out! 🙂

Thanks again,
Chris.

[2oldman]

Do what JBarca did, or make a scale model.

[tonymull]

On any rig or even a car, there is a pivot point and when you get to that point you can cut the wheel as deep as you like and still clear a curve. That was my training with a school bus (just as I could see the corner out the entry door) and a tour coach (just two feet farther back, need the mirror to see that one). Trailers are the same, it's just a matter of figuring out where that point is. Trial and error in a parking lot. It works.

[Bedlam]

Can you overshoot your property and then back in? This would eliminate the choke point of the bridge.

Is there a location farther down the road where can turn around? This would allow you to approach and depart the bridge without an immediate turn.

[JBarca]

Hi,

Maybe this will help. At our current place I have to do a 180 turn to turn the camper around in my yard. It's an ordeal but I figured out a way.

We are building a new home and I did the drafting to layout the new pole barn, house and the barn yard specifically so I can turn around in my new barn yard and it be a non issue. And not go on the grass as spring time the mud in Ohio clay is really bad...

So I did this. On my driveway at my current place, I backed the truck and camper 90 degrees from the drive onto my lawn. This created the skidding and end result of the turn. I did the max turn my F350 would do. Then got out and measured the camper and truck track path impression on the lawn. Then went to the drawing board. OK, the screen and mouse now a days.... This is what I have





My F350, 4x4, crew cab short bed, and my 33.5' camper takes a circle center-line of 54' 8" driving the center-line of that circle to do a 180 degree turn.

In the images you see above, it is 51' 2" from the top of the screen horizontal white parking lot edge line to the centerline path of the truck to do a 90 degree turn, not maxing the turn. Then I back up straight onto that camper turn around pad, do anther 90 deg turn and I'm heading back out of the yard the way I came in. Can back straight into the camper bay of the barn or drive right out driveway if wanted.

This is the length of my rig. You can see how close you come to it


A heads up, if you turn too sharp, be careful yo do not bust the WD hitch. Here at my current house, I take the WD bars off doing all that manipulating. At the new place, I made the turns large enough I leave everything all hooked up.

I have a 2005 new front axle design for the 05's, 4 wheel drive and on the Fords, that 4 x 4 allows a tighter curb to curb turning radius then 2 x 4. 1.8 feet less according the Ford source book for my model year

Hope this helps

John

[frizzen]

Chalk it out on a parking lot. Get a piece of rope equal to the distance from the ball to the axles and have an assistant hold onto the rope so it doesn't drag. Assistant should be carrying a board as long as the trailer is wide to see where the sides of the trailer will go.

[Jaxom]

Get a 5th wheel.