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If you would like to compare quick change payload designs - check out It's industrial looking.
And no cable needed and no getting out of the truck to load or unload.
Nothing like having your own shack on the ground, where you want it, when you want it. RollOffCamper.com
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Creating the Worlds Greatest Work Truck Right away I thought of a mini-roll-off, but soon I realized a roll-off design would have longer than desirable frame rails off the back. I noticed that the only thing on the market for the shorter wheelbase trucks was a hook-lift design. Then I had one demonstrated for me, and I noticed how it swings it's loads over a couple wheels out back. It tipped the load more than a roll-off and having an over the head lumber rack or camper is out of the question. I'd checked out a quick change payload system found on many smaller 15,000 to 20,000 lb. gross trucks. Harold uses them for his recycling business in and around Pierce County. The smaller roll-off system he uses is referred to as the " Hook-Lift." It looks quite ugly and has some disadvantages when compared to a conventional roll-off type system. One thing is that the center of gravity is higher the amount of angle of tilt to the payload when loading and unloading is more than a conventional roll-off system. And above all it is not possible to put an over the cab latter rack or camper on a hook-lift. I had a hook-lift demonstrated for me one day it operated quite fast with an empty bin, but as the driver/operator drove out of the parking lot, the payload box clanged around so much, I imagined paint buckets splashing around and tools being tossed off shelves. Needless to say, I wasn't too impressed with it. I figured that the mini roll-off or as I called it, " Mini Dumpster Truck" design was more to my preference because I thought it would not only look cooler than a hook-lift, but out last one too. I figured that if I'd buy a welder and built a small roll-off system myself, I'd be able to build it for less than the expense of a hook lift. The advantage I realized to the idea was that I would have a welder left over afterwards to build even more payload beds for it in my spare time. Here you have it kids One thing you must understand is that I’m trying to write about my method of dump without disclosing the actual invention. If you happen to already know what the method of dump is – you will understand how I conceived the invention by reading this material. The idea of this segment is to hint around the idea and you just might come up with it yourself. If you do come up with my method of dump without knowing about it beforehand then we can say that I have stimulated your creative juices in the right direction. First off, I realized a conventional roll-off design would be a little bit long for a smaller truck. The problem of keeping it short is the length of frame rails needed for the end of rear carrier rails (or boom) to reach the ground. The rear mounts for the rear leaf springs of the truck's suspension was the limitation for moving the pivot point forward. With the standard roll-off design I knew the carrier rails would have to be about 13'6" to 14' long because of the length need for the carrier's frame rails to touch the ground when the carrier is raised in the elevated position. If the rear frame rails of the truck were to be cut off close to the rear leaf spring mounts, (to shorten the frame) the saving of length would be only about six inches. I figured that if I did trim off the frame rails as an effort to shorten the system I wouldn't have much to mount to. So I thought the best route would be to make use of what was there by mounting to the end of the frame rails. I compared simple sketches I made of the various designs with different locations of the pivot points as an effort of coming up with a way of zeroing in on a design that would be shorter as a result of where the pivot point would be located. I realized an easy way to require less amount of carrier frame rail to protrude from the back of the truck be by lowering the carrier's rear pivot point a method used in some of the older styled drag-on cable type roll off designs. It didn't take long before I realized why the hydraulic cylinders on the older style roll off had were usually mounted in the reverse direction as often used with standard dump truck configuration and the newer style roll offs which comprise a hook mounted on a rotating roller chain. I noticed by lowering the rear pivot point connecting the carrier to the truck's rear frame rails will cause the carrier to move back slightly and if the actuators, (hydraulic cylinders) are mounted in the fashion as to the newer hook and chain models and standard fashion used on the common dump trucks, (having the bottom end of the actuators mounted to the truck's chassis frame forward in relation to the upper end of the actuators mounted to the carrier,) the actuators would have to extend more to make up for the rearward movement of the carrier. This rear-ward movement created by the lowered pivot point sacrifices some of the degree of tilt obtained from actuators extenuation when mounted in the said configuration. I realized when lowering the rear pivot point, it's more efficient if the bottom end of the actuators are mounted to the truck's frame rails to the rear of the upper end of the said actuators mounted to the carrier frame rails. The rearward movement caused by the lowered pivot point forces the actuators to rotate on their lower axis similar the hands of a clock. Instead of the movement created with the standard method, the actuators when mounted in the reverse of standard, (bottom of actuators mounted to the truck frame to the rear of the top)(Like cable roll-offs.) the actuators pivot upward and extend in more of a vertical stance when in the elevated position. I realize that more dump angle can be achieved from the extended vertical stance of the front cylinders with the use of longer cylinders than ones I used on my proto-type because they would force them-selves to rotate further actually tilt backwards to some degree. For a shorter bed length the use of double stage front actuators would be more efficient for such a task, because it allows for an enhanced degree of dump angle. I've improved the dump angle on my proto-type just by moving the front actuators back a few inches toward the front of the rear leaf spring mounts. The dump angle of my prototype was originally about 43 and now it's about 48 degrees of dump angle. If I were to replace the cylinders with ones that are 6 inches longer, I'm sure the dump angle would surpass the 50 degree mark with dump too spare which is good because with having wheels hanging off the back, some of the dump angle isn't able to be used - so more than a 45 degree dump is required if you want clay to slide. If a lowered rear pivot point is used in conjunction with the bottom end of the actuators mounted forward of the upper ends mounted to the carrier, (standard dump truck angle for cylinders) more actuator extenuation is needed to achieve the same degree of dump angle because the lowered pivot point of the carrier causes the movement away from the lower base end of the cylinders. Therefore I realized that having the actuators mounted in reverse of the standard works more efficiently when used in conjunction with a lowered rear pivot point on the carrier. I've seen where a manufacture had used multiple stage telescoping hydraulic cylinders to make up for the lost efficiency. In my opinion the added expense for multiple stage cylinders result in less longevity, less stability, excess weight and an oily mess to boot. But with my own system, I realize with a system less than ten feet long will most likely require double stage cylinders, but that's still better than multiple. And by the time they'll need to be extended, they well be in more of a vertical stance than on a conventional dump system. After examining my sketches, I said to myself, " What if." and I thought the solution to the dilemma would be to put another variable, (an assisting mechanical) into the design. More complex, but... I thought the contraption I'd conceived looked quite strange, but it appeared to be a great way to maintain a shorter overall length. It was able to reach the ground with a short overhang with-out sacrificing the degree of angle when its tilted. As my own design bounced around in my head I realized never seen such a thing before. I had to wonder if it had ever been done before. Although it seemed like a brilliant idea, the worries of why it had not been used before also stuck my curiosity and questions entered my head like: How sturdy will it be? Am I going to find out why nobody has used it before? Will it be practical? Is it worth the added weight?
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© Copyright 2007-08 All rights reserved. Dennis James Sattler
