Tracks Throwback: Trailer De-coupling Accidents Tracks
Tracks Throwback: Trailer Decoupling Accidents By Dick Klein, PE
It’s amazing how many accidents occur because of a failure to properly couple a trailer in a bumper pull trailer combination vehicle (CV). The causes of a de-coupling event are many: hitch ball too small for coupler (2” ball in a 2 5/16” coupler); hand-wheel or latch not properly secured and pinned in place (still open); latch properly secured, but ball clamp not under the ball (ball clamp riding on top of ball). The trailer has two other means of defense for these oversights: the safety chains and the emergency breakaway brakes.
However, these back-ups don’t always work. First, the safety chains have to be in good condition, and not have fl at spots on the links that reduce the breaking strength of the chain. The safety chains must also be rated properly for the GVWR of the trailer (for example, for trailers over 5,000 lbs. GVWR the breaking strength of each chain must be equal to, or exceed, the GVWR of the trailer). Even this does not assure that a new chain does not break under the dynamic loading conditions of a de-couple event, where the tongue of the trailer will be fl ailing back and forth against the chains. If the chains do break, for whatever reason, then there should be an emergency brake system which will stop the trailer, or at least slow it down more than if it had no brakes. However, emergency break-away brake (BAB) systems are only required in commercial vehicle applications, and in those states that have it in the state statutes. Furthermore, the key element in the emergency BAB system is the proper functioning of the independent 12 volt battery contained in a box on the trailer tongue. More often than not, this battery does not have a separate charger, and if it doesn’t, then there is a good chance that the battery is dead. The battery must be replaced every year.
These items are all food for thought for the trailer manufacturer, i.e., how to warn the consumer of the reasonably foreseeable ways he may cause an accident to occur. Here are a few things the manufacturer can do to help consumers:
• Make sure the coupler size is very visible on top of the coupler;
• Make sure the safety chains are of adequate strength; 888.247.7627
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• Make sure safety chains have the proper attachment to the trailer tongue, with “S” hooks that can’t pop out (already a requirement in California and Canada);
• Provide attachment instructions and warnings (including to replace if worn);
• Provide a battery charger for the BAB battery (if so equipped); and
• Provide hook-up instructions and warnings for the use of the emergency break-away system.
The bottom line is to attempt to foresee all the reasonably likely ways the customer can attach a trailer to his vehicle incorrectly and then take whatever steps you believe are reasonably necessary and appropriate under the circumstances to help him avoid or mitigate an unsafe situation.
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