Ok, now on to the roll back. Back a couple posts I attached a couple pictures of a mock-up of the roll back frame. It was a quick mock-up I built out of wood just to see if my concept was sound. It was a simple design but left the bed pretty steep for loading low riding cars. I thought about it for a while and came up with a way to have hinged removeable ramps. Then I could load the car on the ramps that would lay almost flat on the ground, and you could drive the car on them and as you raised the bed it would align with the bed so you could finish rolling the car on to the bed. Then lift the ramps off and they became part of the deck.
At this time, we were in the throes of covid, and most businesses were closed or if not, steel prices were out of control. So, I inventoried what I had in the shop and came up with the final design. I used some C-channel for the main rails and some tube steel for the arms that raised and lowered the bed. I boxed the last 2' of the channels with 1/2" plate and drilled a 3 1/2" hole through it and ran a piece of 3" schedule 40 pipe through it and welded it all around both sides. Then I slid a piece of 2 1/2" pipe through them with a piece of 3" pipe as a spacer to keep it all a lined.
On the lower end I again boxed the frame and welded a piece of 4X6X-1/2" angle vertically to hang just below the frame and sleeve it similar to the ones on the top end. I couldn't run a continuous pipe across that end because of the drive line but I added extra reinforcement to keep it from twisting as I assembled all of these pivot points. I also drilled and taped all of them and installed grease zerts to keep things moving.
On the back of the deck instead of installing a roller like most roll backs, I welded a plate to each side of the truck frame to make a trough and on the bottom, I have a plate welded to a pivot. As the deck comes up and slides back it rotates to stay flat with the deck frame. This "U" shaped trough I left enough room around the deck frame to line it with Teflon panels and added grease zerts to lube it.
Originally, I had planned to use an electric winch to operate the roll back. Thinking if I was able to raise it and gravity would be enough to lower it all I had to do was to control the speed coming down and I could do that with a power in and power out winch. Well, I had everything in place and took it for a test run. Everything worked great. It came up nice and square and I rode it so I could keep an eye on everything to make sure nothing was hitting anywhere or hanging up on something. Well then it was time to lower it. Even with me sitting on the top and bouncing up and down it didn't budge. I had to install a block on the frame just behind the cab and run the winch cable through it to pull it back down. When it got about 2/3 of the way down gravity took over. I was glad I wasn't riding it back down when it slammed down. You could say it startled me, but in reality, it scared the poop out of me it come down so hard.
It became very clear to me I had to be able to slide the deck forward and back under tension both ways. So, I tried to take the cable and routed it around the winch with 3 to 4 wraps and then back through the block and to the deck. That way it would roll on and off the spool at the same rate and stay under tension. Well, that didn't work. As the lift arms came up the apex of the angles would change, and one side would tighten up and the other side would loosen. I worked on this way too long and even tried to come up with some kind of tensioner like on a serpentine fan belt, but it just wasn't happening. Finally, a light bulb came on in my head and I ordered hydraulics for it. And since I needed a pump for that I included a set of cylinders and a diverter value for the cab. With a little more minor fabrication and routing of hoses it worked great, and it is a lot more reliable than I think the cable system would have been.
Next up is finishing up the back deck. Thanks for your continued interest. COCOE
