Dale,
The pipe is 2 1/2 inch diameter. When deployed, the end rests on the housing plate, over a hex bolt head, which you can see on the left, in the second picture. The bolt head keeps it from kicking out to the side. I lower the bed, using the lift valve knob which is secured to the left bottom of the dash. I can do this by myself, although it is easier to have someone help guide the pipe while I lower the bed.
I only have the one pipe. The valve holds the bed steady, without leak down so ordinarily I use both the valve and pipe at the same time, so both would have to fail for the bed to lower. I have tested it with just the pipe and it seems to hold just fine. I estimate the bed weights 1000lbs, so the hinges hold at least half the weight, so maybe the pipe is holding 500 lbs. I would never use the pipe with a load. First of all, before it failed the frame would twist which would be bad.
When I display the truck with the bed up I try to educate people who stick their head and neck over the frame rails that it could be dangerous, but you know you can't keep an eye on it all the time. At times, I have also included a wood block near the hinges to make it safer but I have never tested this and don't know how much safer that would be.
By the way, I cannot take credit for this design. The friend who fabricated this took my idea and made it a reality. We scrapped the original bed frame and he started over, repositioning the lift on the truck frame because it was not installed correctly and designing hinges with grease zerks built in. I use the bed to haul pine needles from my property (central AZ, 6250 ft elevation with Ponderosa pine) to the dump. The bed is pretty high up so I use a step ladder and fill the bed from the front to the back, a very tiring project. To empty it is a joy, just raise the bed, back up a bit, hit the brakes and the entire load slides right out in one compact fourteen foot long brick of needles.
Kent
