The old McMyler Coal Unloader in Port Reading NJ (also known as "Big Mac") was once a vital asset to the operations of New York Harbor, and accomplished an amazing feat of engineering - it could turn an 72-ton rail car full of coal completely upside down, and dump the contents onto a barge. The pier and the unloader were built in 1917, and was so efficient that other unloaders at the Port Reading Terminal were dismantled or used for emergencies. Manned by a small crew of 12 people, Big Mac could unload a rail car every two and a half minutes onto barges destined for NY, CT, and MA.
The theory of operation is quite interesting. A full rail car of coal would be sent out to the start of the pier's ramp using gravity, and then pushed up the ramp towards the unloader using a "pig block" (or "Barney"), a mechanism that would catch the car underneath, between the rails. Upon reaching the unloader, the car would be vertically raised above an unloader pan where it would be turned 120 degrees, spilling the coal out onto the pan in a huge cloud of billowing dust. The pan funneled the coal into a chute which led to the waiting barge; here "trimmers" would work quickly to spread the coal evenly so the boat wouldn't list or overturn. The empty rail car would be turned again, and placed right side up onto a kickback trestle which extended out into the harbor. It resembled a roller coaster in construction; the far end of the trestle curved up into the air where gravity would slow down and stop the car. Here it would change tracks and then travel towards land using another downward sloping track. The video of the model reconstruction below can probably illustrate the process in more clarity.
A pier fire in 1951 caused the dumper to collapse into the water; the heaviest items (cradle, top and dumping pan) were salvaged and the pier was rebuilt. The remaining parts of the unloader were replaced using a similar machine that was purchased in Edgewater NJ. Operations would continue after 4 months of rebuilding.
Reading Railroad was absorbed by Conrail in 1976, but Big Mac was still in service, unloading coal for the few power plants that still used this fuel. It was finally shuttered in 1983, and hasn't moved since. The wooden kickback trestle that extends into the harbor has deteriorated greatly over the years. In April 2010, the pan and chute have actually fallen off the tower, most likely due to the stress induced by the high winds of Hurricane Irene.
Big Mac is the last of it's kind left in the New York area, and although efforts are being made to recognize it's historic significance, the cost and effort it would take to fully restore it would be very high. The unloader is currently located on private property.