Saturday, November 03, 2012

End Dump

I guess I'm just about a weekend blogger here lately - seems with all the election crap going on I'm suffering from burnout. If you are one of my pals on Facebook, you've probably noticed the lack of political crap there from me, too. Nothing I can say will sway someone who thinks our current President is the bee's knees, so enough already. I guess we can all live in food stamp paradise, living our allotted years until we become a liability for the health care program so y'all can feel great about "doing stuff" with other people's money.

Yeah, I said enough already, but I can't help getting a dig in.

At any rate, what we have here I'm sure you've all seen - an end dump rig getting ready to dump. Several of us were waiting to unload (notice the man basket directly in the way), and this guy pulled in.

It's really a pretty sharp KW - nice color and lots of shiny stuff. Most haulers like this truck are usually beat up and rough, never mind the shiny stuff, so this rig caught my eye. Clearly it was fairly new, but some efforts had been made to keep it up. This guy was going for a clean look - no striping or fancy letters on his pretty blue paint. Notice how all his necessary info is on his step. He had already gotten out and released the catch on the rear so the door would swing as he unloaded.

If you look at the front of the trailer, you can see a single ram lifting the dump body. There is a substantial frame underneath with the suspension mounted to the frame, and the dump body hinged at the rear of the frame. This is the strongest variant, but some have a sort of subframe that contains the kingpin (the thing the fifth wheel on the truck attaches to) and the ram, with a set of stringers going back to the rear to keep everything in line, and with the suspension mounted to the dump body. When those guys dump, the front axle gets lifted off the ground and dangles. It's a lighter setup, giving them a better payload. The spread axle rigs really put that front axle in the air. It's not as stable unloading on rough ground as the rig shown here - lots fall over, especially the manure haulers. They unload on soft farm ground, and the load can hang up with one side letting go and the other not, unbalancing the whole apple cart.

He let the rock pile up a bit then pulled forward, because the rock will pile up and prevent more from sliding out.

Really let go here.

Pulling away to let the final dribs and drabs fall out.

Letting it down (it is slow), and latching the rear door closed.

That might not seem like a lot of rock there, but I can assure you it is around 24 or 25 tons - which makes it a legal load for this guy. 50k lbs plus his rig at about 30k lbs equals 80k lbs. If he wants to haul more, he has to lighten up or put more axles underneath.

But I'm sure he's figured all this out, this is a shorter trailer, so it's pretty maneuverable compared to longer rigs. His tractor is fairly short too - he does have a single bunk, but this is obviously a local hauler. He's not going coast to coast with this puppy - I'm sure he does quite well with the local jobs he undertakes.

In most states I'm aware of, "rock" haulers are exempt from the Federal Bridge Gross Weight Law (or the bridge law to a trucker). This law is intended to keep heavily loaded axles a certain distance apart so that there isn't too much weight loading in one spot, overcoming a bridge's ability to hold said load. These guys are exempt as long as they are hauling rock, gravel, refuse, building debris, whatever - as long as it's considered exempt. Grain or feed products are not, so when they load those commodities, legally this rig can in no way approach 80k lbs gross - he's way too short. Doesn't mean a bunch of them don't try it anyhow, but they're not supposed to. If the one of the various alphabet trucking regulatory agencies catch 'em, it's an overweight fine, and perhaps mandatory unloading of part of the commodity until they are legal.

So, this is a little peek into another facet of trucking you might not really know much about.


Jess said...

I was dumping one on a project, when the driver stopped, lowered the bed and stepped from his truck - obviously shaken.

When I appeared as dumb as I was, he asked me if I saw the wheels off the ground. He went on to explain how he could see the back duals were at least a foot off the ground before he lowered the bed.

We moved the truck to flatter ground and he dumped the rest of his load.

drjim said...

How many cubic yards can a trailer like that hold?
Being a "civilian", I tend to think in terms of volume, and not weight.

Jeffro said...

That is a good question, drjim - and it totally depends on the type of trailer and it's volume. That trailer is probably a 24 footer, 96" wide, and how ever tall the sides are might give you an estimate, since it's narrower inside and a shorter length. Some I've seen that will hold eighty or so yards are multi axle and a LOT longer. Then there are the tub trailers that have the angled front ends and the rounded bottoms - they haul a lot of large scrap demolition stuff and not having any corners inside makes a huge difference in how it unloads.

Just to be thorough, I looked up what the average ton of crushed rock equals as far as a cubic yard, the figure is 0.6796cu3, so 25 tons would equal 16.99 cu yards. Of course that trailer would hold a LOT more rock, but it would be VERY hard on the truck/trailer.

drjim said...

Thanks, Jeff!
The only other experience I have with stuff like this is loading Liquid Oxygen on the Launch Platform at work.
It takes THIRTY-SIX tankers of LOX to 'fill er up'!

Road Pig said...

They've come a long ways from the old cable dump we had. Talk about unsafe!

lisa said...

I know just a little bit but it is always nice to learn a little bit more!