Dump truck question

[BGlidewell]

I see a lot of HD dump trucks hauling dump trailers. Why is there such a long tongue on the pulled trailer? Looks wierd but I suspect there is a good reason. These tubular tongues looks like they are more than 10' long.

 

[Babyfat]

I Would Say So They Can Dump And Spread Like Roads And Driveways Without Unhooking, I've Seen These West Of The Mississipi But Only Once Here In Mich And It Was A Ca Truck Here For A Show

 

[Dl5treez]

So they can spread, and also for weight limits.



Typical 8 axle truck & pup configurations haul ~105,000 pounds. Some states require specific lengths for different weights--so the longer tongues, some of which are sliding, help keep the max payload capacity up and still keep the trucks legal.



Back home in Washington state it's not uncommon to see 20 feet between the truck and the pup. They get pretty long & run out to the 75 foot maximum on many occassions.

 

[NIsaacs]

The long hitch is to keep the trailer tires/axles a certain distance from the truck tires/axles. This is to meet the "Bridge Law". In order to haul the maximum gross weight of 80,000 lbs, you need a required amount of distance from the truck to the trailer. This keeps the total load from crossing the little bridges that you see on old two lane roads. First the truck weight is on the bridge, then the trailer. The same thing applies on spread axle trailers, if you have at least a 10 foot spread between the trailer axles, you can carry 20,000 lbs per axle, instead of 34,000lbs for the two in close tandem. Some states allow an extra 6,000 or 86,000 gross for this feature, some states do not.



The Dump Truck system you are looking at will unhook from the trailer, dump the truck load then return to the trailer, pull the load and box off the trailer onto/into the truck dump bed and then dump that load. They are called Transfer Dumps. It makes it easier for the "10 wheeler" to get around under cramped conditions v/s the whole truck and trailer.





"NICK"

 

[abdiver]

Transfer Dumps also known as Slam Bams

 

[Hoefler]

It allows for dumping their loads without unhooking. They back up and jack knife the pup to one side, dump the tractor, pull forward to straighten out, back straight back and dump the pup in front of the previous pile.

 

[NIsaacs]

I think the original post was about transfer dumps. I am using the light weight tubular hitch as the basis for my guess. If it is a transfer dump set up, the trailer can't dump on it's own, the box has to transfer to the truck to dump.





"NICK"

 

[BGlidewell]

thanks all for the really great answers!