My Bed design

[trimster]

50 minutes ago, Steve from SoCal said:

Is your trailer level with the hitch compressed now?     Can you raise the pin box on the trailer then raise the hitch?     Looking at that hitch, you may be able to support the spring tray by using a wood block under it to bear on the steel plate.     Are the springs providing a level trailer with variable pin weights?      

The pin box "looks like" it has a cutaway from the plate how much relief is there between the plate and the arm that goes back to the trailer?     Do you know what the pin height is on the trailer?     

Steve

Trailer is level on the Volvo. I had to lower (extend down) the pin box as far it would go and raise the hitch by one increment. The hitch can be raised another 2.5". There's bolts on the side of the side-plates that hold the lower spring tray in place. Moving those up would be the same as putting a block under the tray. On the MDT (shown in the photos), I had to have the hitch in its lowest position to get the trailer level

The issue with these springs is that when the trailer is hooked up and running down the road (earlier photo) the springs are at about 70% compression. Should be closer to 60%. At 80% they start to appear to the load as a solid object. That's why I am going to get 2 stiffer springs for the outside positions.

The 'relief' is 2" over the run of the pin box arm.

The pin height, when running level, 45".

 

[Steve from SoCal]

The pin height typically is 47~49", you could raise the pin as much as possible to 47.5" along with the 2" relief that would give you some breathing room.     

 

The suggestion to block the spring box is relieve some of the tension on the side plates, using the block to support the forces transmitted to the spring pack.    Given the spring profile, maybe do all of them to get a better range of motion. 

Steve

[Star Dreamer]

You may want to make the ramps accessible from both sides. You may find situations where it may be better to load/unload from the driver's side in a campground. Better to have the capability and never need it, than need it and not have it. You can still use the extra space for storage, just don't build the wall. 

[phoenix2013]

On 12/2/2020 at 10:39 AM, trimster said:

Noteven:

So I kinda did that 'line projection' activity and found that unloaded, the hitch is 2" above the planned bed height. My concern is when loaded, it squats 2"+. The suspension, as seen in an earlier photo, is not air driven so pumping it up to maintain ride height is not an option. The photo below shows it on the road when mounted to the MDT we had.

But I do have 2 options and one is not a good plan due to the design (or lack thereof) of the hitch. I can raise the suspension several inches by adjusting the tray that holds the suspension 'air springs'. This increases the side-to-side forces through leverage. The side plates on this hitch are already marginal. So I hesitate to move the load-point up.

The second, better, plan would be adding box tubing under the hitch. Thru-bolt it to the base mounting plate. If I raised the overall hitch height 3", the top of the hitch would be flush if not a tad higher than the deck under full load. I'd feel a lot better about that scenario. Would it then be to high to allow for a hitch hole cover to fit when the head is removed? Should (nebulous word). I can figure that out easily.

The lateral forces on any hitch are enormous on any hitch in any turn and at 90 degrees or close to it they become 100% of what you see in straight pulling. Your concern about side plates being able to handle it is spot on. Since you know what the "squat down" of the pucks is with your pin weight, I would suggest that you "overmount" the hitch and pinbox in height so that things end up at 47 inches when hooked up. Level pulling is a must.

[trimster]

Ya, that's kinda what I did. I raised the adjustments of the hitch and dropped the pin box down. It now pulls level. Putting riser-blocks under the hitch, to elevate it seems like a good plan.

I just corresponded with the folks who produce Sumo Springs and they have these style suspension springs in densities higher than what's offered with the hitch. The next step up is 4000# at 50% crush. I'm thinking 2 of those placed in the outside positions might mitigate how much the hitch squats. It would give me load head-room if needed. Right now, the hitch when loaded, has 1.5" of downward travel. All that against a suspension (the springs) that are very close to full compression,  appearing to be a solid to the movement. I need to get range of motion back.

I also plan on adding  vertical plates between the sides to stiffen those. 

Edited December 5, 2020 by trimster

[jenandjon]

23 hours ago, trimster said:

I just corresponded with the folks who produce Sumo Springs and they have these style suspension springs in densities higher than what's offered with the hitch. The next step up is 4000# at 50% crush. I'm thinking 2 of those placed in the outside positions might mitigate how much the hitch squats. It would give me load head-room if needed. Right now, the hitch when loaded, has 1.5" of downward travel. All that against a suspension (the springs) that are very close to full compression,  appearing to be a solid to the movement. I need to get range of motion back.

I am very interested in how this works out. I am familiar with sumo springs. I didn't realize they could be or should be used in this hitch. Please keep us posted when you install them.

[trimster]

So, there were two mfgs of this style of spring/suspension units. The ones on my hitch went out of business...at least they do not offer them anymore. The folks at Sumo have on their self in their R&D area, the springs in my hitch. Well, not mine, but they got a few to see what the competition was up to. They are the same technology.

The Sumo folks have a pretty cool kit for trailer suspension as well. And kits for the front axles on our HDTs.

What I will be doing is buying a kit for a Ford 450 front suspension. It has a bonded mounting plate on the bottom that I need to remove and then bore a 1" dia. hole into the bottom of the spring, which sets on an alignment block in the hitch. The spring dia. and height are workable in the hitch.

They have several similar springs with different weights (resistance specs). The ones in the hitch now are about 1500# each. But that 'resistance' spec is kinda fluid. It's not linear like a traditional steel spring. And the spec/rating is at 50% compression. So the pair I am looking are rated at 4000#...as a pair....not individually. My roughly 2800# pin weight will compress these about 30% or a bit more. This will give the hitch more bottoming-room which I lack now.

Not sure when I will get these. It's on the list. Building the bed comes first.

[trimster]

Question to you welding/design pros. Looking at the drawings I put up in the first post, and specifically the edges of the bed where the ramp storage boxes are. 

The bed frame outside rail is 2x4- C channel. The ramp boxes cut into this rail leaving 1" across the top, of the original 2x4 steel. I don't have a way of cutting this kinda notch (3"x 22"). So I am thinking about creating what you see in the drawing. The C channel gap is joined with 1"x2" angle to crate the top edge, and then backed with 1"x4" rectangle box. The angle and box are welded to the 2x2 ribs running across the bed.

Will this construction support a Smart car driving up on the bed? I will have the aluminum ramp support brackets on the edge of the bed, which will help distribute the load a bit more, across the welded seams.

Thoughts on this are appreciated.

[Darryl&Rita]

I wouldn't say that it's too light, but a test case could be welded up real quick to prove the suitability.

ETA: Don't forget the weight bearing capacity of the decking plate.

Edited December 6, 2020 by Darryl&Rita

[Lance A Lott]

If you put the 1x4 tube under the angle it will stick down and be very difficult to weld as it probably wont fit tight into the corner of the angle. Perhaps use 1x 1/2 flat backed up by the 1x4, I am assuming the floor will cover it, you probably won't need the 1x4 you could use 1x1 instead of 1x1/2. You could also replicate the ramp rack with steel welded into the bed this would at strength. 1/4" deck by its self would probably hold a smart I will try to send you some photos of what I did.

[rpsinc]

Also consider that the dimensions noted in postings above done consider wall thicknesses.  I.E.  a 1X4 tube can come in various thicknesses of walls, which will affect its capacity considerably.  And also in C-channels- all are listed in height and weight, rather than in flange size.  I.E.  12" X 20.7# is a hearty channel, not for your project but for one I am working on right now.  This same 12" channel is also available 25#, & 30# meaning weight per lineal foot of channel.

So sometimes using combinations of sizes and wall thicknesses, you can arrive at a solution that might not have been considered before.

[trimster]

10 minutes ago, rpsinc said:

Also consider that the dimensions noted in postings above done consider wall thicknesses.  I.E.  a 1X4 tube can come in various thicknesses of walls, which will affect its capacity considerably.  And also in C-channels- all are listed in height and weight, rather than in flange size.  I.E.  12" X 20.7# is a hearty channel, ......

Ya, I need to match the C-channel thickness so it will look seamless when welded, ground flat, and painted. The place where I get my steel is good about helping us newbees with stuff like this. I bring in drawings and explain, and they make-it-so (as Picard would say).

[Steve from SoCal]

The design you show has a clever idea with the ramps below the car.     Because of the span 22" between X-members and no outer support it is weak by design.      The edge of the deck will have to support the weight or a good percentage of it and the ramps while loading.      The things I would do to strengthen the deck and add support are, attach braces from the outside edge of the deck to the frame.     The deck itself is thin and spans a wide distance, 1 or 1 1/4" angle welded as cross supports every 9~10".

 

The pic below is the ramp door I build to drive my cars up it is 2X3 rails with 1 1/2" angle as the ladder.

Steve

 

[trimster]

The cross supports where the weight of the vehicle will set is a good idea. I added them to the drawing. They are 1x4 tubing.

The reason for the tubing over angle as you did...I am screwing the deck plate down. That way I can remove it to service stuff below a bit easier.

The front (right most in the drawing) ramp box is directly over the existing steps to the back of the truck. The other side of the car/trike wheels will ride on the cross member just to the right of the middle ramp box. In fact, it will be right on the cross member.

Edited December 8, 2020 by trimster

[Darryl&Rita]

Bob, just a thought. Make the support beams removable. The lattice structure looks too tight for much work, even with the deck plating removed. A third member isn't a small thing.

[trimster]

2 minutes ago, Darryl&Rita said:

Bob, just a thought. Make the support beams removable. The lattice structure looks too tight for much work, even with the deck plating removed. A third member isn't a small thing.

"Removable" That means they would be bolted to the bed frame rail and just rest on the truck frame rails? Or maybe bold to those as well? Wonder if it's worth all the drilling, welding in tabs, etc.  Great idea however.

I'm going to noodle on this one.

[Steve from SoCal]

Rectangular tubing is weak in that position,  use 1 1/4 .187 angle like I did it is under an inch high points up.    Secure your deck panels to the X-members not the stringers.     The strut braces should have at least a 30 better more angle to the truck frame, extend the brace mounts down below the frame rail to get the right angle.    The struts don't need to be at the very edge of the body.      You want to minimize deflection of the body cantilevered from the truck frame, anything close to 3/4's of the open span is good. 

Could you build the deck frame in two sections with a break right behind the back ramp?     That would allow you to remove the entire section for access.     

Steve    

[Darryl&Rita]

1 hour ago, trimster said:

"Removable" That means they would be bolted to the bed frame rail and just rest on the truck frame rails? Or maybe bold to those as well? Wonder if it's worth all the drilling, welding in tabs, etc.  Great idea however.

I'm going to noodle on this one.

Ours has the bracing welded to the underside of the 1/4" deck plating, with the ends tapered to rest on the main frame. The main frame members are pocketed to let the removable plate sit at the same height as the plating welded to the main frame. We used 2x2x1/4" angle for the bracing, and stitch welded it to the plate.

[trimster]

21 hours ago, Steve from SoCal said:

Rectangular tubing is weak in that position,  use 1 1/4 .187 angle like I did it is under an inch high points up.    Secure your deck panels to the X-members not the stringers.     The strut braces should have at least a 30 better more angle to the truck frame, extend the brace mounts down below the frame rail to get the right angle.    The struts don't need to be at the very edge of the body.      You want to minimize deflection of the body cantilevered from the truck frame, anything close to 3/4's of the open span is good. 

Could you build the deck frame in two sections with a break right behind the back ramp?     That would allow you to remove the entire section for access.     

Steve    

Understand about the rectangular tubing. I was figuring that a 20" span of thick wall 1x4 would be fine between the cross members and there's a plenty of them. The angle would be cheaper and less welding.

I'm not sure I can put struts from some kinda frame drop structure to the underside of the x-members. Maybe one between the front 1/4 fender and the fuel tank and another at the back of the frame. No way can I get one between the tires/axles unless I cut huck bolts to get access to the truck frame. I understand the reason or desirability to put in the struts, not sure I have seen them on most beds I have looked at. Maybe I missed them. I did consider making the cross members 1x2 C channel. It's just a lot of work if you need to put in a piece joining the space between the cross members. Square tubing is easier...for me to deal with. I would like to see photos of a bed installed with the struts.

Ya, the deck could be built in 2 section breaking right after the front ramp box. I'd just double up the 2x2 at the joint and bolt through them.

[trimster]

Steve from So Cal mentioned putting braces under a few cross members to help with flex.

Engineering wise, how strong are the 2 x 2 ribs? From the point where they connect to the frame-rails, to the outer edge of the bed will be 30". Would it be stronger to use 1x2 C-channel or stick with the 2x2 thick wall tubing?  The outer bed rail will be 2x4 C-channel.

Haven't purchased the materials yet. Thought it might be a good time to rethink some up-coming decisions.

Bob

[noteven]

 These body builder manuals have useful information

Volvo - section 7 frame

Kenworth T680-T880 body builder manual

Body attachment to frame is section 7 in the KW manual - illustrated. 

Both section 7...who knew?

 

 

Edited December 17, 2020 by noteven

[Darryl&Rita]

1 hour ago, trimster said:

Steve from So Cal mentioned putting braces under a few cross members to help with flex.

Engineering wise, how strong are the 2 x 2 ribs? From the point where they connect to the frame-rails, to the outer edge of the bed will be 30". Would it be stronger to use 1x2 C-channel or stick with the 2x2 thick wall tubing?  The outer bed rail will be 2x4 C-channel.

Haven't purchased the materials yet. Thought it might be a good time to rethink some up-coming decisions.

Bob

There's free online calculators to figure the different ways to support a load. They may not be exact, due to limited input, being free, but they do give a general idea of posiblities.

[trimster]

So, second draft of the bed design...without the beaver tail. Looks like it's do'able with the hitch height. I can always raise the hitch if needs be.

This gives taller rear storage cabinets. I'm thinking 2 roll-out drawers on the passengers side. The drivers side will have the generator on a rollout. These cabinets are 30" deep, close to 30" tall and 20" roughly, wide. Going to check if I can have them power coated black on the outside. Painted white on the inside.

Still working on a way to allow for most of the bed to be removed in one piece should that be needed. The ramp boxes cut through the bedframe and the outside bed rail, so there's no continuous piece of steel front-to-rear. With 3 D-ring pairs spaced down the bed It could allow for weight bearing points that would take the stress off the weaker points. Still noodling.

When I have the bed mostly framed up, I'm taking it to the fabricator for them to build and put in the ramp boxes, rear tool boxes, and possible skirting around the tires. They'll also cut the top deck plates. I'm screwing those down so they can be removed if needs-be.

With the weather hovering around the 40's (on a sunny day), ya, welding and drilling just ain't in the cards. But I'm building brackets and such in the shop. I need to fabricate a wiring harness for the 'chicken' lights that will go down both side and the read of the bed railing, power to possible lights in the tool boxes, and heavy lines back to the cab from the generator for an inverter, etc. 

Oh, where do I look for wheel chalks? Suggestions.

Edited December 28, 2020 by trimster
Trying to figure out why the images are not showing. Hmmmm.

[trimster]

Behind the bumper is this 4x4 tube that runs through the bumper mount, to both sides of the frame extension. It also supports the receiver hitch. I have to guess the fabricator put it in because it might be required? for rear impact. I forgot to ask.

Can it be cut off, more or less, flush? It would allow me to put in a bigger storage box behind the wheels.

 

Edited December 28, 2020 by trimster

[Darryl&Rita]

13 minutes ago, trimster said:

And can anyone tell me why my images are not showing up?

Strip the "IMG" off the front and back of the image link, after you copy/paste it into the "other media" button.