The Case of the Capricious Carburetor

My e-mail reply to A recent comment by a reader of these "Calamities" columns brought back my memory of a bizarre incident involving an engine-powered lift truck. While employed as a staff engineer for what was then a major fork lift manufacturer, I got a request to assist the eastern zone service manager in analyzing the cause of an alleged forklift "run-away."

The owner claimed that the fairly new truck had faults that caused the accident, and demanded a replacement forklift. The zone man picked me up at the airport and we traveled to the docks of the New York Port Authority. This being the pre-containerized freight era, the place teemed with dockworkers manually moving crates while fork lifts roared back and forth picking up and moving pallets of goods to waiting trucks. At this time, dockworkers seemed to rule the roost, and typical tribute for no work disruptions included shares of imported goods such as bottles of Haig & Haig scotch, small appliances, and various other imported luxuries lifted from cargo.

Scene of the Crime

The zone man explained that the run-away forklift seemed to pick up speed heading directly to the dock's edge which was close by. The driver bailed out just before the truck sailed into the cold Atlantic water. The lift truck had been recovered and brought into the dock maintenance shed. At our request, the dock maintenance crew removed the engine compartment covers and the seat and seat deck.

The Investigation

We were able to closely inspect the accelerator pedal, throttle linkage and carburetors. Carburetors! The zone man and I both were wide-eyed as we eyeballed the two units assembled so that the airflow from one passed through the other. Now, there are such things as dual-fuel lift trucks, but the bill of material for this machine showed that it was ordered, and left the factory with an ordinary carburetor for gasoline fuel only. As I continued the inspection, the zone man, who was on good terms with dock lads, questioned them about the extra carburetor. He learned that the engineering staff of the Port Authority wanted to test a dual-fuel lift truck. Their idea, and it made some sense, was to run the forklift on gasoline outside, but switch to LP fuel with its cleaner exhaust, when lowered into a ship's hold. Rather than buy an available dual-fuel conversion from the after-market, the engineers had a "better idea" and designed their own system.

While we took a closer look at the execution of what seemed to be a commendable concept, the maintenance crew regaled us with laughable, but hair-raising stories of drivers intentionally crashing lift trucks and abusing other equipment-mostly when a break from work was wanted. While wondering if this "run-away" off the dock was one of those excuses to take a break, I continued my inspection.

The Smoking Gun

The engine wouldn't start; no surprise, as when the truck went into the drink it inhaled water and the pistons hydraulicked, bending the con rods or breaking other internal parts, so we continued a visual and tactile inspection. Whoever installed the LP mixer (carburetor) had altered the throttle linkage.

I found the throttle linkage was directly connected to the carburetor throttle plate shaft, which effectively bypassed the torsionally sprung governor linkage. Worse yet, there was no throttle linkage stop adjustment, and extreme pressure on the accelerator pedal resulted in the throttle arm going over-center on the throttle shaft with the potential to lock the throttle wide open. From this evidence I concluded, and my report so stated, that the truck was assembled and had operated correctly when delivered, but the unauthorized, incorrect carburetor modifications put the forklift in a potentially dangerous condition.

As we finished our inspection, I put the idea of driver sabotage out of my mind as one of those urban legends we all have heard. Or were these just fanciful stories? The dock crew continued with their story of this machine. It seems that when this forklift did its belly flop, a hired diver was sent down with a crane hook. Soon, the diver returned to the dock, pulled off his mask, and with a puzzled look on his face, asked, "Hey-which fork lift do I hook onto?" The maintenance crew told us that when a certain dock-goon was desperate for a rest and couldn't break his forklift, he would drive it off the dock. When this particular day was done, they had pulled up five lift trucks!

I later learned that the Port Authority had accepted their responsibility and bought a new lift truck.

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