(Thanks for all the answers about my cable shovel questions.) Next question: Why do some haul have a straight cab protector on the dump box and yet other trucks of the same model have a curved piece? It it for the type of material hauled? Capacity?
Simple answer, they are different body types. Long answer, I'm no expert (though I'm sure the experts will chime in soon enough to fill in the blanks), but you'll find that in an iron ore mine the beds are much shallower than in other applications, because the material so dense and heavy. Also in coal mines, the trucks hauling exclusively from the vein have very large bodies because of coal weighing so much less. I would have to imagine that the curve you see is part of a lightweight body designed to hold the maximum amount of material for the lowest weight bed. These beds commonly will have rubber liners as well to decrease the weight further. Another fun trick, is the heated beds, where the exhausted is piped through a "web" of tubes in the bed to help cut down on sticking material and haul back, though it's not recommended for those rubber lined beds (burn rubber, literally). Hope I could help in my novice bits of knowledge:drinkup
Basically, the flat style cab guard is the more conventional design that has been around for many years. Many operations have found that material will build up and stick to the flat canopies when it spills over from loading the box. To counteract this, some manufacturers of dump boxes have added a curved cab guard to help shed excess material that spills onto the canopy to keep it from building up. One other reason is that is is harder to load a curved canopy, but it can be done. Shovel operators sometimes have a tendency to "bag load" the trucks. That means they put part of the load on the canopy. This happens for different reasons. Sometimes it's because they aren't paying attention, sometimes it's to give the trucker a hard time dumping it....(the more material loaded onto the canopy, the harder time the truck has to lift the box, since there is too much weight, too far forward), and another reason is that the material is light, so, in order to get their payload numbers, they have to put more material on the trucks. Generally, the management wants the numbers to be up, but they don't want trucks bag loaded. Hope that answers your questions a bit. Feel free to ask more, anytime.
These are great questions you are asking. You have stimulated some very good discussion with them. This looks to be another good one. Alco hit on the main reasons, but there will be more I'm sure
Not called the headache board for nothing!!!!
Gavin I'd say someone should have that shovel operators .....er, hide, for loading that little stone.
The Head Board is NOT a Rated Structure and is strongly discouraged from load Placing on it! Head Board Loading changes your Axle Splits and accuracy of the Payload measuring system! If you move a Bucket Load foward Payload accuracy can be out 5-10% and you have change the Load over the Front Axle which Only has 2 Tyres and takes the load away from the Rear Axle that has 4 tyres. See's a massive increase in Front Wheel Bearing failure, Hoist Cylinders and Front Strut life is drastically reduced! Chops out front tyres as your Toe is changed as the front Bows lower. Must we go on............
Duratry Suspended Body I have seen that curved cab protector on Duratray Suspended dump bodies. Although I'm not sure if is exclusive to Duratray. The Duratray body has a suspended rubber mat, instead of a steel floor. Here is a link: http://duratray.com.au/index.html
The only bed manufacturer producing rounded canopies that I know of is Duratray, and those are the only rounded canopy bodies that I’m familiar with, so I am only speaking in direct correlation to that particular bed design in this post. The rounded canopy is manufactured for use in the most extreme truck-loading conditions; extremely heavy materials, or high production pass-matching (2 pass turn-outs, with >100 ton bucket payload capacities). The rounded design provides a mechanical advantage to the bed. The extreme duty Duratray’s have a skeletonized bed-frame, which has a rubber liner, reinforced with wire ropes. This enables a lot of the weight of a steel bed liner to be removed from the bed, increasing payload capacity. Numerous other benefits to the vertically curved canopy have already been thoroughly covered in previous posts. The wire ropes in the rubber bed liner are affixed to the bottom of the bedwalls, which are rounded, not vertical as in a standard dump body. As the bed is shock-loaded (primarily from the first pass) the rounded bed catches the load and dampens the shock, which saves on maintenance and enhances operator comfort. That shock-load reduction is not only achieved via the dampening effects offered by the rubber, but also as the rubber liner bottoms out on the skeletonized frame, it places tension on the wire ropes in the bottom of the bed, which pulls down/inward on the sides of the bed (very minutely, the bed is not truly flexing), by rounding the bedwalls, they’re stronger than if they were straight/square. By continuing this circular distribution of energy across the rounded canopy of the extreme service beds, the energy is naturally carried by the vertically rounded canopy which essentially creates a circle. We all understand the increased strength properties of a circle over a square. A cross section of a traditional truck bed is a square. A cross section of an extreme service Duratray bed is a circle. Under the most extreme operating conditions, Duratray’s with straight canopies could begin to form tension cracks in the bed along the canopy joints where shock load energy would create a shearing affect. By vertically curving the canopy, the circular “pipe” effect is better able to distribute the energy from extreme shock loads. This also translates into prolonged frame life of the truck, as the bed absorbs a greater portion of the energy distributed to the truck. This is especially beneficial on trucks made with softer steel/weaker frames that are known for having abbreviated frame life; particularly Liebherr’s. For the great majority of operating conditions, the standard bed/canopy configuration is ideally suited, and in many instances offers benefits, making it the industry standard for truck beds.
There are several other manufacturers producing bodies with rounded canopies. SMS Equipment is the one I am most familiar with. The other one I can think of is in South America, but I can't remember the name for the life of me. The reasoning you have posted makes sense with the Duratray bodies since the canopy would provide structural strength for the design, but I think it would be much less of a consideration for a steel floor design. This picture is an SMS body.
Dicsa Tricon or DT high load is the Chilean body you are thinking of Brian. I worked for 18 months with 8 830E trucks (yes the Cat guy has worked on No 2 stuff!!!) with these brand of bodies and i was amazed what they can do, 26 ton is all the body weighed and i have worked at other sites with 93,s where the body weighed 62 ton!!, not only was the headboard rounded but with that brand of body it is extra high and virtually impossible to load any rock on. I swung a PC5500 fully loaded bucket into the back of one one day trying to operate and it bent outwards at the back by at least 2 feet, slewed back to centre and it just sprung straight back to were it should be, lucky!!
Thanks Gav, I knew somebody would have the answer. As soon as I read it, I had to kick myself for not remembering what it was. I guess my mind was elsewhere....off to Vegas in the morning.
There are a lots of information about big haul trucks. I like to see that how men can lift heavy and large stone and other this by help of machinery. Very amazing.
Hell no, that would most likely get you a promotion wouldn't it?!!!
Strange dump bodies Here is another use for a dump body at Christmas. Happy New Year to every one
You now need a "Spagetti Truck" to carry the Limes????