After a few near misses, J&J Snack Foods Corp. knew it needed to find a better way to protect its employees from accidents caused by unscheduled over-the-road truck departures from its shipping docks.

"We wanted to find dock equipment with a high level of reliability and low maintenance requirements," says Phil Heffelfinger, director of engineering for J&J. The previous safety system was often out of service and expensive to maintain.

J&J, which manufactures and distributes snack foods and beverages in Pennsauken, N.J., was introduced to a trapped key interlocking device (Castell Interlocks Inc., 724-816-8223). The device locks out the trailer and then interlocks it with the dock door. This trapped key ensures that the trailer can't be pulled out unless the door is closed and the dock attendant is safely inside the building.

To make the new device even more effective, the company instituted a new procedure for loading goods. First, drivers report to the shipping office, where they receive a lock specific to the dock door assigned to their specific trailer. The lock has a uniquely coded key trapped inside. After the trailer is docked, the driver chocks the wheels and attaches the lock to the trailer's emergency gland hand fitting, releasing the key.

The driver then inserts the key into an exterior control panel, activating a light inside the building to indicate to the dock attendant that it's safe to open the door. Only after the key is inserted into the control panel does the automatic door's push button become powered and the door become operable. Once the door is opened, the key is automatically trapped, and loading can begin.

When loading is complete and the dock door closed, the control panel releases the trapped key. The driver then removes the lock from the trailer and returns it to the shipping department.

"We require the drivers to return to the shipping office, then we give them their paperwork so they don't accidentally drive off," notes Heffelfinger.

An additional benefit of the process has been energy savings. "Previously, our dock attendants would sometimes open a door prematurely while they waited for the driver to properly spot the trailer," Heffelfinger says. "This process saves us a lot of money on refrigeration costs too."