History and Use of Lockrods
– Lockrods were patented in 1912 and were originally used to secure railroad boxcar doors.
– Lockrods have evolved to secure trailers and containers with swing doors.
– Swing doors are commonly used on tractor-trailers, intermodal cargo shipping containers, certain rail cars, and smaller utility trailers.
– Miner Enterprises was the originator of the lockrod and owned the patent.
– Lockrods are sometimes confused with locking bars or bar locks.
– Powerbrace Corporation, a subsidiary of Miner Enterprises, manufactures lockrods, trailer door hinges, and security lock devices.
– Trailer doors are secured to the end frame of the trailer to prevent cargo shifting and maintain proper alignment.
– Racking can occur if there is too much play between parts, leading to wear and failure of door security.
– The end frame components of a trailer typically consist of hinges, lockrods, trailer doors, and the framework.
– Trailer doors must swing freely and be easily opened and closed while securely holding the cargo.

Lockrod Construction
– A lockrod assembly consists of top and bottom cams, a rod/stick of tubing, and a handle assembly.
– Keepers are the parts that accept the cam and can be welded or bolted onto the end frame of the trailer.
– Mounting hardware attaches the lockrod to the doors.
– The end frame of the trailer endures the highest forces during loading and unloading.
– Lockrods come in different lengths and thicknesses depending on the intended use, with heavy-duty models being one-inch in diameter.

Types of Lockrods
– Zero-torque lockrods were invented by Powerbrace and have become an industry standard.
– Zero-torque lockrods have cams that go past the center point, providing tighter engagement with more pressure applied from the inside of the trailer doors.
– Reach/gather lockrods have the ability to reach and engage the keeper while closing the door, overcoming resistance from compression seals and warped doors.
– Icebreaker lockrods have high door opening leverage and can open frozen doors.
– Manufacturers have designed different types of cams/keepers combinations to solve specific door alignment problems.

Lockrod References
– http://www.galvanizeit.org/hot-dip-galvanizing
– http://www.evidencesolutions.com/web/Articles-by-DA/how-to-safely-open-trailer-van-doors.html
– Wafer Tumbler Lock
– http://powerbrace.com/

Lockrod Facts and Statistics
– Lockrods were patented in 1912.
– Powerbrace Corporation manufactures lockrods, trailer door hinges, and security lock devices.
– Lockrods come in different lengths and thicknesses, with heavy-duty models being one-inch in diameter.Sources: https://en.wikipedia.org/wiki/Lockrod