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double frame - stupid question

21K views 8 replies 8 participants last post by  diesel dan 
#1 ·
What's the purpose of a double frame? The only thing that I can think of would be to raise the bed of the vehicle. Thanks
 
#4 ·
duunoit said:
What's the purpose of a double frame? The only thing that I can think of would be to raise the bed of the vehicle. Thanks
A double frame on a truck is for strength, but what I think you mean is the subframe that sits on top of the main frame of the chassis that you commonly see on smaller dumps.

Usually it's a smaller frame that the dump body hinges off and the hoist is mounted to. That way it comes as one single piece that's just bolted to the chassis frame of the host truck. It does create extra clearance above the truck chassis.
 
#5 ·
A double frame to me what I have always heard of it refered to is a frame ( c channel) inside of another frame (c channel) for higher gvrw vehicles, takes some of the twist and flex out of very very very rough terrain applications
 
#6 ·
good rule of thumb on trucks to carry work bodies, beds, etc, go with a double frame. as stated, it takes the flex out of higher weight carrying trucks, that are subject to off road use. concrete,dump and oil field trucks that are bought for this intended purpose, nearly always have a double frame. running a dump bed on a single frame truck is doable, i have done it, and seen others do it with sucess. general rule of thumb, a dump bed with it's own sub frame is the ticket under these circumstances. i have seen some take regular weld on dump beds, and install them on single frame trucks ,and hold up. but generally with time, problems arrise.
 
#7 ·
A guy that hauls stone for me when I need 100's of tons has a single frame Pete tri-axle and runs a C-10 CAT in it (maybe 340HP?). He claims the lighter (non-doubled) frame, lighter diesl engine & driveline combined with a lighter aluminum bed, tanks, alcoas and air suspension allows him to carry 1.5 tons more stone on each haul than a double framed tri axle with a 500HP CAT with spring suspension. Of course he says that once loaded, the truck is slower than a 500HP truck, but unloaded it drives great. All those 1.5 ton extra loads add up!

He's an older guy that's been hauling for like 50 years and I respect his opinion.

On a single axle or construction truck used on jobsites a lot, i'd recommend a double frame, too.
 
#8 ·
MY kw is double framed from the back to the front spring shackels to keep it from giving. It is very heavy and does cut down on payload ,but the only time I run that hevy is haulin grain to town. Ive learned if you have to worry about scales the lighter you can spec your truck the better off you are.
 
#9 ·
All of our IH county highway trucks have double frame. We order them that way because of the weight of an underbody plow and the front plow. Our single axles loaded with sand, sander, and all the plows are probably pushing 55-60k. We have about 4 or 5 4900's with 290-300k miles on them and still runnin strong with zero frame issues.
 
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