Trailer Kingpin Restoration

There are many difficulties with various truck and trailer parts that truck drivers and mechanics alike have to deal with on a weekly (if not daily) basis. One of the most often overlooked (and one that can exacerbate the damage from any accident) is the trailer kingpin. It’s true that the trailer kingpin is a tough piece of steel and certainly doesn’t break easily, but when it does, that’s when the media breaks yet another terrible story of a massive accident, thousands of dollars in damage and possibly fatalities.

As such, it is incumbent upon the trucking companies to do everything possible to ensure that the trailer kingpin suffers from excessive wear and to repair or replace any kingpins that are excessively worn. The details of such excessive wear and tear are no secret, and the 2010 CSA certainly puts the federal and state requirements in plain language, but the method by which trucking companies meet the requirements is less clear.

The first option that inevitably comes to mind is the replacement of the entire bonnet. This involves the mechanic cutting through the trailer floor from below and cutting through all the brackets that anchor the kingpin to the trailer before removing the old kingpin. The kingpin is then removed using a carbon or oxyacetlyn arc. The new pin is then re-welded and the cross members are replaced.

There are several minor issues with the above option. First of all, kingpin removal is usually done with oxyacetlyn, as carbon-arch technology is not as widespread. This can lead to some damage to both the frame and backing plate due to metal rusting and may contribute to difficulty in the future. The replacement and re-soldering process also comes with its share of difficulties. Since the rewelding is done through the same small opening in the floor, and new metal is added to the old cut pieces (a procedure that is difficult at best when access to the pieces is not restricted), the above Rusting can lead to potential catastrophic kingpin failure at worst, and at best, increases the chance that repairs will need to be done more frequently.

Replacing the kingpin and support plate assembly can eliminate the difficulties mentioned above, but it comes with its own corresponding difficulties, namely price. A complete replacement of the support plate assembly can cost between $3,000 and $5,000 US dollars, and can mean leaving a trailer behind for long periods of time.