A tractor-trailer fifth wheel along with a kingpin provides the coupling link between the truck cab and the semi-trailer it will be hauling. Despite its name, the 5th wheel is a horseshoe-shaped coupling device while the kingpin is a, roughly, 2 inch to 3.5 diameter inch steel pin that is inserted into the center of the fifth wheel. This kingpin then moves against the greased fifth wheel providing stability and securement for the semi-trailer. However when a truck kingpins fails, the coupling mechanism will also fail resulting in a runaway truck trailer. This runaway trailer can strike other vehicles traveling along the highway or roadway. Due to the large size and significant weight of truck trailers, these accidents often produce catastrophic injuries or even death.
Truck Drivers Must Perform Significant Maintenance on the Fifth Wheel & Kingpin, but Some May Neglect These Duties
The maintenance of a commercial truck often falls into a commercial driver’s hands. Unfortunately, the stresses and responsibilities of the road can cause these duties to be neglected or performed improperly. When a driver does not follow the steps to properly secure a trailer, the risk for a serious accident or injury due to a run-away trailer increases significantly. Steps essential to proper kingpin and fifth-wheel use and maintenance include:
- Ensure the fifth wheel is clean — Many manufacturers suggest a regular steam cleaning of the fifth wheel. In practice, many trucking companies do not perform the steam cleaning since they prefer to scrape off the debris or to use solvents to break down the remaining dirt and grease.
- Inspection of fifth wheel plate – The driver should ensure that the plate is flat, it has not warped, and that it has not cracked. Cracks in the trailer often allows grease to leak creating environmental and safety issues.
- Ensure that the locking mechanism is in working order, then adjust and test it – The driver should ensure that the locking mechanism has not worn down or been damage. A damaged locking mechanism increases the likelihood of a trailer rollaway. The driver should be familiar with the manufacturer’s recommended procedures to adjust the lock. Regardless of manufacturer, a test pin is the proper tool to test the lock. A driver should always use a test pin.
- Inspection of brackets and pins – A kingpin gauge should be used to check for wear and tear. If there is damage to the kingpin, it should be replaced.
- Ensure the component parts are properly lubricated – The locking mechanism and the jaw of the truck should be greased with a light oil or silicone-based lubricant. The bracket pins should be lubricated with the assistance of another through use of a grease gun. The bracket pins must be lubricated on both sides. Finally, a high-quality grease should be used to lubricate the top plate.
- Drop the trailer with care – Drivers should use the truck’s air suspension when connecting the truck cab to the semi-trailer. When the driver has aligned the cab properly and he or she is ready to drop the trailer, he or she should crank the landing gear so that it is close to the ground. Then, prior to pulling away, the driver should release the suspension air to reduce the forces acting on the trailer.
The above represents only the general guidelines a drive must follow to perform proper trailer maintenance. Drivers should always consult the manufacturer’s instructions to ensure that they are providing proper vehicle care.
Defective or Worn-Out Trailer Kingpins Can Cause Severe Injuries or Death
In January 2015, a runaway trailer accident on I-95 near Greenwich Connecticut nearly cost a mother her life. A commercial driver from New York was driving a tractor-trailer carrying corrugated cardboard when the truck approached a gentle curve on the interstate. As the truck entered the turn, the coupling gave way and the trailer detached from the cab. This out of control trailer then slammed into a Toyota Rav-4 SUV, skidded across the highway, and pinned the SUV against and partially on-top of the center barrier.
The driver of the SUV recounted the harrowing events stating, “As [the truck] was crushing me against the Jersey barrier, I didn’t realize the trailer was detached. I kept waiting for [the commercial driver] to turn away. It seemed to be forever. Then I thought, `I’m going over.'” The driver in this accident was lucky. She only suffered a sore neck and back. However, the situation could have been significantly more severe. The driver was issued a citation for his failure to properly secure the trailer.
In a 2012 New Jersey accident, the driver of the passenger vehicle was not as lucky. While driving on I-280 in neighboring New Jersey, a man was killed by a detached semi-trailer. The New Jersey man was driving behind a tractor-trailer in the highways left-lane when the 50-ton trailer became detached. The detached, runaway trailer collided with the Honda that was following behind. The driver was pronounced dead at the scene.
Finally, consider the events that unfolded in a July 2014 detached trailer accident in Arkansas. A driver was traveling with her boyfriend at approximately 70 mph in her Pontiac Vibe. Here, a tractor-trailer ahead had its trailer detach from the semi-cab that was towing it. A driver following behind the truck said she did not have any time to avoid the truck and could only hit the brakes. She says, “[the truck] just hit me.”
Both the driver and her boyfriend sustained extremely serious injuries. The driver suffered a broken femur, knee and hip. She states that she now has a screw in her knee and several staples to close a four-inch gash that went down to the bone. In all, 60 staples were used to close her wounds. Her boyfriend suffered a broken leg.
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However, some claim that this particular accident could have been prevented. Arkansasmatters.com interviewed a local auto-service shop about this accident and how it could have been prevented. He stated, truck-trailer and cabs coupled properly do not come apart. He estimated that roughly 90 percent of detachments were due to improper coupling. However, he also said that there is a fairly fail-proof way of preventing the cab and trailer from separating: safety chains. Even if the kingpin or fifth wheel fails, the safety chains can prevent the trailer from careening down or across a highway or roadway.