History of the Locking Pliers

In 1921 a Danish blacksmith, William Petersen, realized that his smithy job would be made easier if he could combine the convenience of pliers with the holding power of a vise.  Being an inventor of sorts, Petersen came up with the idea of a pliers that could be locked by turning a small knob at its heel, giving the user more leverage and torque – LOCKING PLIERS WERE BORN.

1924 Petersen Patent original sketch for the Auto Locking Pliers

April 8, 1924 Locking Pliers Patent

Petersen won a patent for the locking pliers in 1924. In 1934, he formed the Petersen Manufacturing Company which opened its first manufacturing plant in 1938.  

The first Petersen Factory and its workers at the assembly line

In 1939 as part of President Franklin Roosevelt's WWII initiative to aid England's defense against Germany, thousands of Petersen’s locking pliers were sent to aid England’s aircraft industry.

After the U.S. entered the war, the “Great Arsenal of Democracy” started manufacturing “Liberty Ships”, to transport men and material to allies and the various fighting theaters over the entire world. The ship builders quickly realized that the Petersen locking pliers was the ideal tool to help them build their boats. To save time welders simply welded Petersen’s locking pliers into the hulls rather than taking the time to remove them from the bulkheads they were holding and welding together.

Construction of the Liberty Ship and its workers

The construction of a Liberty ship

After the war, Petersen's Locking Pliers took on a new look and improvements continued to be made up to the 1957 model, which is the mainstay in many tool boxes today. Petersen continued to work on improvements but died in 1962 before his plans for a one-handed, automatic locking pliers could be completed.

Thirty-nine years after he died, Petersen’s original concept was finished by engineers who found his conceptional plans in a shoe box and his dream of an automatic locking pliers was finally realized!

Today, the AUTO-GRIP® Locking Pliers, which is the great-great-great grandson of William Petersen’s original locking pliers, is the tradesman’s choice because it combines the convenience of the locking pliers automatically clamping on thick or thin material with the efficiency of no manual adjustment.

Our Modern 2019 8

2019 Auto-GriP®


AUTO-GRIP is a trademark registered with the United States Patent & Trademark Office. Any unauthorized use is expressly prohibited.  All rights reserved.