Hauling Limestone

Bulk Carrier unloading limestone.


This is a Great Lakes Freighter, a self-unloading bulk carrier. Marquette, Michigan is a major port for iron ore with a major iron ore mine nearby. Freighters like this one, bring in limestone (called flux stone by the iron smelters), and haul Taconite pellets (Iron Ore) out. They also bring in coal for two power generating plants, and coal for the open pit mine. The mine mixes the limestone, with the ore, to concentrate the ore, and produce what it called Taconite pellets. The limestone mixes with impurities in the ore during the smelting process, combines with silicon, and floats to the top of the pool of liquid iron.  


This is a 42 wheeler, gross vehicle weight is 160,000 pounds. The rear trailer (called a pup) is a full trailer with a fifth wheel and a draw bar which connects to the lead trailer, (called a lead), which is a semi-trailer and connects to the truck tractor with a fifth wheel on the truck giving three degrees of articulation. You will learn how to back this rig up. There is a remote control locking mechanism that will lock the fifth wheel on the pup, leaving you with two degrees of articulation. You get good at backing up or you don’t work.  The truck has an eighteen-speed manual transmission, and you will use every gear in that tranny, except for low-low gear. There are hills to climb, and descend, and there is an upgrade at the mine that will drag you down to a complete stop if you don’t shift gears correctly, and a second upgrade at the ski hill that is equally as steep a climb. If you screw it up, you will use that compound low gear and everyone will laugh at you if they are not stuck behind you cursing you for making them wait. Worst case, you have to get the mine loader operator to pull you up the hill.


Somebody had the bright idea of organizing a bicycle road race, and brought in racers from all over the country, and routed the race up that same ski hill while we were working. We had to climb that hill in low range, with some imbecile on a bicycle inches away from sudden death, riding alongside the truck. The day that President Bush came to visit, I refused to work. Which turned out ok because the Secret Service shut the operation down for that day. No oversize, over weight trucks on the road when the President is in town.

During the summer months, we hauled twice what the mine needed, called ‘stockpiling’ because the bulk carriers don’t operate when the lakes are frozen over in the winter. We hauled limestone half way to the mine where there was a rock quarry operation that had space to store the several hundred thousand tons of limestone that we hauled in. During winter months, we hauled those tons of limestone the remaining distance to the mine.


The image above is the beginning of the stockpile operation. Once this layer of limestone has been unloaded, a ramp is cut in one side of the layer, and you climb the ramp up on top of this layer where you build another layer. Then another ramp is cut, and you climb up that ramp to the top, and start yet another layer.

It is necessary to disconnect the pup from the lead trailer, to dump the lead. Then you back up to the pup, with enough accuracy to capture the draw bar, and reconnect the pup to the lead.

Hook UP

These connections you see, including the two safety chains you can’t see, must be disconnected, and then reconnected every time you dump. You are working on a schedule and have a finite amount of time drive up to the mine (or stock pile), unload, and get back to the docks for another load. If you are slow, you miss the last load of the day, and your work day gets cuts short as does your weekly paycheck. You are driving this 160,000-pound vehicle like it is a F1 race car. Your boss has a stop watch, and if you want to get paid, you make your lap times.

Ten Inches

This is the draw pin. Note the size of the safety chains behind the pin. The hole in the bottom of the pin is for a safety clip that prevents the draw pin from working up and out of the draw bar.


This is what backing up to the pup looks like to the driver. Notice that the lead trailer dump body is still descending.


This is what it looks like if you do it right.

Notice that the front two tires on the pup are lined up with the last three axles on the lead trailer. You will see those two axles on the pup line up when the draw bar is captured by the lead. The draw bar can be offset in the horizontal plane and will still be captured. It can also be offset in the vertical plane and if it is too far out of alignment, it will go under the lead trailer and cause damage.


This is called stacking where the loader operator will push up the material you have dumped to the maximum height the loader can reach. Then you drive on top of that material to start another level



In the image above, the driver is coming down from the second layer, where a third layer is being built.


This is the inbound route. Climb the short ramp to the top of the first layer, make a hard-left turn, and climb another, steeper ramp up to the other truck. When a layer is first started, it is a very small area. You dump your load over the edge, to widen that layer. Do it right, and the loader operator is happy. Get stuck on the ramp, or get stuck by going too far over the edge, and the loader operator is not happy. In the beginning, the ramp has not been compacted enough by the heavy truck traffic and it is easy to get stuck. In the winter, after the pile of limestone has been frozen, they use an excavator as a jack hammer to break up the limestone that begins to resemble concrete.


This is what it looks like from the top.


And this is a perspective.

There are two types of limestone, and two stockpiles. Maybe it was three. I have forgotten. I used to have the numbers, but have long since forgotten how many hundreds of thousands of tons we hauled. It was a killer job.  Twelve hour days and eight on Saturday. The stress was unbelievable. We had one driver who died from a heart ache while unloading.

It was a job that made me crazy at times. I did it for three or four years; don’t really remember. To this day, I can not believe that we didn’t kill anyone.

Another company came in and underbid the contract. Most of the drivers were immediately hired by the other company.



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