Semi Based Trailer - Hitch placement question

[les_garten]

You can actually build a 48' trailer and be legal IF you forgo a deck. The average length limit used is 65 feet, a 48' trailer gives you 17' to work with. Most trucks have a published BBC measurement. That is the distance in inches from the front bumper to the imaginary back of a day cab or the end of the sleeper. A Volvo 780 is 189" that leaves you with a very close 15", perhaps a 47 0r even 47.5' trailer would be a better fit with that cab. A deeper pin 48-50" will give you a trailer with little to no nose swing. In theory a 16" gap would be enough but, you would be right at cab extensions and be real careful on driveways. There are a number of trucks running tight kin pin settings where the trailer is just a few inches behind the cab extenders. You would also has a lower drag profile and get better mileage. The trucks with close coupled trailers generally run 22-24" gaps, that gives you enough wiggle room in a high angle ramp. If you are really set on a 48' trailer a air slide fifth wheel with a forward stop at 65' would solve the problem. You slide the trailer forward if you come across a situation where length may be an issue?

 

Steve

 

 

Thanx Steve, very interesting information here.

[rickeieio]

In many, if not most states, 45' is max length for an rv, trailer or MH. I believe that's true everywhere east of the Mississippi. Somewhere, likely in the resource guide, there's a list of length laws.

 

Wouldn't it be nice if the laws were uniform?

[les_garten]

Also regarding the mini cooper, there was someone on the forum a while back that had one that was building on bed for it on a long nose freightliner. I think he was also trying to put the car at an angle to shorten it up some but was having trouble finding the maximum angle that was allowed for the motor. I believe he had some health issues and sold the HDT before it was finished. You might find the postings by doing a search.

 

With a low sitting car like a mini, you also have to watch your break over clearance which might mean longer ramps and then where do you store them.

 

You can build a bed that will allow you to drive over the hitch but then it won't work with a typical semi pin arrangement on the trailer. I know because I am having that issue with the Space craft trailer we are designing.

 

Dave

 

 

Are you able to build a deck at all with the Spacecraft Semi? Looks pretty tight between the trailer and the frame as it is.

[Jack Mayer]

 

 

Are you able to build a deck at all with the Spacecraft Semi? Looks pretty tight between the trailer and the frame as it is.

Sure, it just has to be a step-deck. The smart or other deck cargo is on a deck that is the "conventional" height for haulers. Then at the hitch it steps down to the height required to clearance to the trailer (eg. the clearance is (mostly) on the truck, not on the trailer, like a conventional 5th).

[les_garten]

 

 

 

 

(eg. the clearance is (mostly) on the truck, not on the trailer, like a conventional 5th).

 

I heard you make that statement in another post, I didn't understand it then, I get it now, thanx!

[Star Dreamer]

Sure, it just has to be a step-deck. The smart or other deck cargo is on a deck that is the "conventional" height for haulers. Then at the hitch it steps down to the height required to clearance to the trailer (eg. the clearance is (mostly) on the truck, not on the trailer, like a conventional 5th).

 

 

You have to step down at the point of allowing the trailer to do its swing. We start stepping ours down just in front of the hitch and works with our current trailer but our hitch head needs to stick up above the deck by about 8" to allow for trailer tilt if we had a semi style trailer. After looking at our truck when we stopped by earlier this year, Spacecraft has some ideas on how to make it work (mainly by using a dropped pin).

 

You can see our issue in this picture.

 

 

Now granted, I have a higher deck than most at the front portion but you would pretty much have to get the deck about level with the frame rails at the area of the trailer swing to allow for a trailer to miss it.

 

Dave

[Jack Mayer]

Yes, you can do a dropped pin on the trailer.....Wyatt and I discussed this in the past. I'm not sure I really like that idea, though, since it has implications on the floor level of the trailer. You cannot have it both ways...there has to be some clearance on the truck if you want the flat floor.

[phoenix2013]

I have a flat floor fifth that is actually lower in the front than Marsha's semi units, the pin is level with the top of semi frame. It required placing an ET on the bottom flanges of the frame and the deck was sunk about six inches below the top of the frame (on either side of the hitch) to allow for clearance of the fifth outside edges in off camber turns.

It's been done and built and you can see the truck in Port St. Lucie, Florida, give me a call.

You can see some of the detail here.

 

Note how thin the deck is in the rear and below the top of the tires and the top of the rails in the center.

[les_garten]

I have a flat floor fifth that is actually lower in the front than Marsha's semi units, the pin is level with the top of semi frame. It required placing an ET on the bottom flanges of the frame and the deck was sunk about six inches below the top of the frame (on either side of the hitch) to allow for clearance of the fifth outside edges in off camber turns.

It's been done and built and you can see the truck in Port St. Lucie, Florida, give me a call.

You can see some of the detail here.

 

Note how thin the deck is in the rear and below the top of the tires and the top of the rails in the center.

 

 

Thanx, I sent you a PM