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The Human Chock Block

The Human Chock Block
GUNNERY SGT. DEAN DODSON
Headquarters and Service Battalion
Parris Island, S.C.


I am a mechanic by trade, but I paid my dues and worked my way to floor chief as a sergeant at a headquarters battery. Experience has taught me to read the maintenance manual every time I work on my vehicle. It lists the dangers that can be involved with any of the components on which I may be working. This is also true for the maintenance manuals that deal with the items in the Marine Corps’ — or any other branch of the armed forces — inventory. A close call while preparing for a field operation served as a reminder of just how important it is that we do our jobs by the book.

It was that time of year some Camp Lejeune Marines in artillery dread — Operation Rolling Thunder, a field op at Fort Bragg, North Carolina. It’s not that Marines of different military occupational specialties can’t prepare or operate in the field. Can’t is not in a Marine’s vocabulary. This operation was dreaded because it meant a lot of extra work behind the scenes (which no one up top seems to understand unless they are familiar with logistics and support). It also meant more road time for operators moving gear back and forth, and more miles on some of the equipment. At the time, we had various pieces of rolling stock, which included several of the infamous Dragon Wagons — the MK 48/16 Logistics Vehicle System and M870 trailers.

After a certain number of miles, the brakes on the M870 need slack adjustment per the maintenance manual at that time. The shop chief wanted these adjustments done after every drive to and from Fort Bragg, so two mechanics worked on either side of the trailer as it was pulled into the maintenance bay. At the same time, quality control personnel would inspect the vehicle for defects before loading it for the next day’s run. This was also per the maintenance and operations manual preventive maintenance checks and services schedule.  

As Mechanic A was finishing the work on his side of the trailer, and before QC could perform its inspection, a situation arose where an LVS was needed for another task. Since the other two LVSs were unavailable, the one in the bay had to be used. Mechanic A was tasked with unhooking the power unit and getting it over to the trailer that needed to be moved. Mechanic B was still conducting the slack adjustments under his side of the trailer when Mechanic A released the king pin and, on his way to the cab of the power unit, picked up the prescribed chock block and placed it on the fender. As Mechanic A was getting into the cab, he hit the trailer parking release button to push the air that was still left in the air tank system to the trailer brakes.

As the gooseneck of the M870 trailer slid down the skids, it came to rest on top of Mechanic B, who was lying between the tires on the driver’s side of the LVS. I was tending to other concerns on the floor when I heard the expletives exploding from Mechanic B as the weight of the trailer was coming to rest on top of him.

Several of us ran to Mechanic B while Mechanic A raced back to the front of the vehicle in an attempt to start the engine to build up air to move the LVS. Mechanic A had forgotten he had unlocked the king pin from the fifth wheel. Mechanic C noticed the dog down chains were still looped into the tie down rings and brought this to the attention of the other mechanics attempting to push the trailer to release some of the pressure on Mechanic B’s ribs. Mechanic D jumped up to make sure the chains were connected as Mechanic C quickly rushed to get to the overhead crane controls to move it over what would be the chain’s apex point. With Mechanic C’s calm thinking and observation and problem-solving skills, we hoisted the trailer off Mechanic B. He was escorted to the battalion aid station and the incident was reported.

This accident taught us the importance of getting back to the basics. First, communication is important between mechanics working on a piece of equipment. Second, chock blocks are required under any piece of equipment a Marine is working on, including a trailer. Third, make sure no one is lying beneath a piece of equipment you are connecting or disconnecting from a vehicle. Lastly, if you’re working on a vehicle as a team, help the other mechanic finish their work unless you are reassigned. Until that time, continue to do what you can until both of you are finished.

So what happened to Mechanic B? Amazingly, he returned to us the same day with a diagnosis of bruised ribs. How can this be, you ask? Well, he was a big, corn-fed hoss from the Midwest. This accident might have been worse had he not been so stout or had a smaller build. In the end, we all learned an important lesson, and Mechanic B gained a new story to tell about how he became a human chock block.

  • 1 July 2014
  • Author: Army Safety
  • Number of views: 14356
  • Comments: 0
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