Selected Feature Stories

© 2001 Door & Access Systems
Publish Date: Fall 2001
Author: Tom Wadsworth
Page 42

Technical Tip

In the Loop?

Are you “in the loop” on loop systems? One of the earliest known garage door opening system was a “loop system,” invented in the 1930s.

The “loop” is a continuous piece of wire that is embedded into pavement. As in the early designs, detection of a vehicle moving across a loop can be designed and installed to activate the opening system. Detection can also be designed to keep the system in the “open” position until the vehicle has safely passed through the opening.

Since the 1930s, though, most door systems have been activated by radio controls. Consequently, many dealers are not “in the loop” about these systems, which are becoming more common.

DASMA’s Operator & Electronics Division has created a special Technical Data Sheet (TDS 354) to acquaint dealers with the basics of loop systems and their relationship to depth in road pavements. Loop systems can affect the pavement, and the pavement can affect performance of the loop detector. TDS 354 describes these effects and offers some solutions and considerations.

TDS 354 is free of charge and can be obtained by contacting DASMA at 216-241-7333, fax 216-241-0105, or