Subframe decisions...... :(

[dzzz]

So I've procrastinated as long as I can. My 13" "flatbed" Alaskan Camper with no cab over will be ready in about 5 weeks.
It's going on a stretched U500.
My current (somewhat bizarre) plan is to put the camper aft on a 17' frame, with 4' of storage between the truck and the camper.
So from front to back:

Truck cab --> 4' gap storage ---> 13' camper

Again, the Alaskan is just a big rectangular box. No cab over, no side cutouts that are needed for a pickup truck bed.

The bottom of the storage will be flat cabinets with house batteries, espar, and spare tire. The flat top (open to elements) can hold bikes, motorbike, extra water tank, etc.
1) Is that just too weird?
2) Should the storage subframe be part of the camper subframe, or separate?
3) ideas on craning on and off the tire and motorcycle?

Design goals are:
- keep weight between axles, balanced and low
- put batteries and espar out of the camper, but near the engine.
- be able to carry bikes/motorcycle easily and out of the dirt.
- have the flexibility to carry a lot of water

Ideas?

 

[Metcalf]

So is the extended deck going to hang out over the rear axle a long ways, or is the wheelbase on your 'mog pretty long? I think its a good idea to have the storage space in front of the camper if it doesn't make the entire thing too long overall. I'm sure that camper isn't really that light, and hanging it out past the rear axle would be a mistake in my opinion.

As long as your not in a hurry a simple hand crank jib crane should be able to handle unloading a spare tire and/or a motorcycle. The main issue will be coming up with a location for the crane that lets you do both effectively. I guess it all depends on how complicated you want to get with the overall design. I don't know if you can get away with something like a ramp to load the bike. I just think the bed is going to be too high. You will most likely have to have some kind of cradle for the bike to attach a lifting point.

I designed a u-shaped crane for a project once that needed to do something kinda similar to what you need. I'm guessing your will be unloading the bike much more than the tire, so that may need to be your main focus.

I'll sketch something up......

 

[dzzz]

Since I stretched the truck 3 feet (to a 4800mm wheelbase), the overhang isn't bad. With a 17' bed the total vehicle is just under 26 feet, which was my max length target. (10.5 feet tall, 26' long, 200 gal. diesel, 150 gal. water)

 

[UK4X4]

4 ft gap

aluminum lift frame with both bike and spare installed

1 lift mechanism for both.ie truck width frame with mounting for all toys
and storage....ATV winch and arm for example

you won't push a decent sized bike up above the level of a mog frame.......unless its a 50cc or your name begin's with hulk.

or your just a profi trials rider and just ride it on up !

 

[Metcalf]

This is the basic idea I had in my head. Just a rough concept but I hope you get the idea....

 

[dzzz]

Very interesting, Brennan. It solves the problem of getting the motorcycle away from the vehicle to lower. It also doesn't require level ground.
It would also work with UK4x4 idea of lowering a whole rack of goodies.

Now to figure out how to lower the tire with the same device.

 

[dzzz]

How did you come up with 4ft? Tire diameter when laid flat? With a "U" crane you might be able to reduce that somewhat if the tire was stored upright & perpendicular to the frame nestled with the bike.

I worked out that if I ever want to do a Unicat style camper that it would be 17'. From talking to Charlie he said that he would have extended his wheelbase. I didn't want to build up the truck and then completely tear it apart if/when I wanted it bigger.

To stay unconnected for long periods often requires carrying a lot of fluids. To carry a lot of fluids requires a heavy duty truck. To carry that fluid between the axles requires a longer wheelbase. 17' is about as long as I can go while keeping an excellent departure angle and a square back.


My main water will go in the camper storage to avoid freezing. I want to be able to configure the truck for extra water, and I probably don't want to do that under chassis. My toilet is cassette, and my gray water is under sink.

Originally I was going to lay the tire flat. But for removal/replacement it became clear that it was easier to have it upright. It should look pretty good too.

Edit: I have thought of a headache rack as protection in a front end accident, and possibly rollover. Brennan's hoist as a lift would be an easy way to get to the storage

 

[Metcalf]

Thanks, Lowering the tire wouldn't be a big deal, you would just have to unload the bike first and then go back and get the tire. You might have to turn the tire sideways if the tire was wider than the U-frame....not a huge deal. I would have the frame set up to unload the tire to the side of the vehicle that wasn't facing traffic.

You could have the bike sit on a frame like you mentioned....that way you could load stuff other than the bike. I don't think you would want the tire on there since it would cause such a weight imbalance most of the time.

 

[Ford Prefect]

With the size of the gap and the size of the bike I question your ability to turn the bike sideways and use a crane to get the bike out of there and down to the street level on a crane.

IF you settle that, I personally would just use an electric winch. Go out and find a nice little warn, say, 1000 lbs or even 500 if you can find a decent one that size. It would be more than enough to lift your tire and bike on and off.

Mount the bike to come up the passenger side, and the tire to come up the driver's side. Then you can either just get a crane that can be relocated to either side by lifting it out and dropping it into a slot, OR you can get a crane that pivots in the middle with an arm that can extend out once it is facing the right direction.

Or you could just see how cool you think you are by trying to jump the bike off of the back of the mog! haha


If you use that idea above, sounds like an interesting engineering feet, but otherwise I do like it a lot. It would also reduce your need for a crane. Just make sure the arm sticks out past the edge of the truck (say six inches) Then you could hook the winch to the tire or the bike.

Very cool idea there Metcalf. How do you feel about dropping the hydraulic ram and using a winch instead. The reason I ask is that it would take one heck of a ram to be able to fold up that small, and open that long.

 

[dzzz]

Sideways? The orientation of the bike remains constant on and off the truck. The crane has two arms with a bar in between. The bike (or whatever) stays between those two arms.

The bike on the ground is lifted by a hoist and guided between the two arms. Once lifted and oriented the arms are rotated. If the operator is standing on the truck, the hoist failing is still safe. The only other safety factor is a crush injury from the arms being operated hydraulically.

An interesting problem is to figure out a way for the crane to work with only one power source (a linear acuator or a winch).

I would just have an attachment point on the crane, with a removable hoist

 

[UK4X4]

The way you have drawn it you could use the same arm to lift and lower both bike and car,

but bike first and then tire,

You also probably would not require a n frame just 1 arm

as the tire would need to drop lower a block or ratchet could be used

to lower the diference between bike height and tire

with a lift off frame you only lift once - but the weight increases- probably need a n frame support for that.

Don't you have a hydraulic take off on your Mog ?

or just add to the power steering circuit- its probably man enough for the odd use

 

[dzzz]

I have four or five hydraulic circuits with controls. It's not expensive to do Brennans plan. Loading/unloading the spare may be somewhat awkward. But making the crane a bit longer and having it rest above the tire at the cab roof line may allow the tire to swing over the cargo.

The problem with one arm is that centered it takes up the most valuable space. If the one arm is overbuilt to allow a 2 foot offset it likely negates any cost advantage over two arms.

 

[ntsqd]

Why does the tire need to be that high? Can it not lay flat, but under the truck's frame?

 

[Metcalf]

Are you planning on just one bike? If there was two I would lean toward the use of a simple platform/cage that allowed you to load/unload both bikes ( or cargo ) all at the same time.

I think using a hydraulic ram to control the u-frame crane would be the best. I think if you limited the angles so the force on the frame was minimized you could get away with running a single ram on one side. The frame would have to be slightly stronger, but you would save a lot of complexity. A single hydraulic circuit with a spring loaded closed center valve would be pretty darn simple. That could be mounted out of the way under the bed in a little lock box.

You could get away with something like a turn-buckle adjustment to move the frame if you didn't want to have the hydraulics, but it would be much slower.

Another option is some kind of electric linear actuator, but I would have to look pretty hard at the loads expected. I'm sure they make something that would work, but are hydraulics or electronics a better option?

To do the lifting your going to want something designed for lifting generally. Most ATV size winches would work, but I would question the brake a bit since its not really designed to be an overhead lift. Its just comfort level......

The tire could be drug sideways up onto the bike/storage platform and then turned sideways.....not a big deal. You should be able to use a strap looped around the tire through the center hole in the wheel. You wouldn't have to disconnect the strap to turn the tire....

I think this is the simplest idea for what you need overall....but I can think up about 3-5 other ways to do it if you give me a few minutes

 

[dzzz]

Why does the tire need to be that high? Can it not lay flat, but under the truck's frame?

At almost 4', the tire doesn't fit between the frame rail and the outside line of the truck. Laid flat above the rail it would be difficult to drag out, as it can't be handled by hand.
Sitting upright it can be hoisted off easily.