Locked In

April 23, 2007
When the wheels don't move, neither do the trailers. A close up view of the Power Chock. (Top) The Power Chock system at dock doors. (Bottom) Rite-Hite's

When the wheels don't move, neither do the trailers. A close up view of the Power Chock. (Top) The Power Chock system at dock doors. (Bottom)

Rite-Hite's STR-4000 system secures trailers horizontally and vertically.

It's estimated that one of every four trucks arriving at loading docks can't be held by their rear impact guards (ICC bars) because they weren't originally installed on the vehicle, have fallen off or are bent or damaged. Trailers that aren't secured to the dock can creep away, creating unsafe gaps that in worst case scenarios can tip a forklift moving into and out of a trailer during loading and unloading. There are a number of devices and techniques for keeping trailers at the dock, some of which present simple solutions.

With dock safety problems brewing for two separate companies that handle beer, each turned to the Power Chock vehicle restraint system from GMR Safety Inc. (www.grmsafety.com), headquartered in Terrebonne, Quebec.

Prior to installation of the equipment at the Toronto facility of Molson Coors Brewing Co. (www.molsoncoors.com), some docks had no restraints and others had hydraulic devices designed to grab and secure the ICC bar at the back of a truck. The brewery handles around 100 inbound and 100 outbound loads each day, according to its distribution manager, Steve Ropp.

"I found the hydraulic dock locks were good for a while but as they started to fail they became very costly," he says. "With the Power Chock, there's virtually no maintenance and yet I find them to be a very safe device."

Mounted to a counter-balanced arm, the 18-in. high tensile steel chock sits on a galvanized steel ground plate. Offered in two models, the devices can include exterior and interior lights, control panels, alarms and sensors. The system used at Molson is integrated with the dock plate. Once a dock plate is in the back of a trailer, if anyone moves the Power Chock, an alarm sounds. When the plate is out of the back of the trailer, the Power Chock can be removed and the and the system's lights change.

"The neat thing about the system's warning lights is that no one has to hit any switches to change light colors," says Ropp. "It's automated. When the right conditions are met, you have a green-yellow-red scenario. Just look at the light orientation and you know what conditions you're under. If the inside light is red and outside is green, the truck driver can back the trailer into the dock and put the Power Chock in place. Once the system is set, the inside light turns green, the outside turns red and you know the truck driver can't pull away. The forklift driver inside is safe."

Molson has health and safety rules stipulating that workers can't go into a trailer unless it is chocked. "Even when we have a dock-restraining device that grabs the ICC bar, our rules are written so that the driver has to put a chock in place anyway," notes Ropp. "Rubber chocks would slide and move but the Power Chock just stays in place."

Like Ropp, Ron Wenzel, operations manager of Central Distributors of Beer, Inc. (www.cdob.com) in Romulus, Mich., was experiencing high maintenance costs with aging equipment designed to keep trailers in place at the dock. The largest distributor of Annheiser Busch products in Michigan, the distribution center handles about 3,000 loads a year inbound and services 42 of its own outbound routes daily.

When one of the dock doors was damaged beyond repair, Wenzel felt it was time to look at the entire system with an eye toward upgrading it. Working with the company's material handling vendors, managers became acquainted with and chose the Power Chock because of the potential maintenance savings.

Bulk delivery to many of Central Distributors' chain store customers is increasing. To make these deliveries the company uses a rear end trailer with a lift gate on the back. The lift gates didn't work with its old dock equipment. With the Power Chock, it's not a problem.

"We kept it pretty simple," claims Wenzel. "All of our nine dock doors will have the Power Chock system so a truck has be in place before our dock door will even open. That way we don't have to worry about open dock doors which is really the only safety issue we have."

To prevent trucks from pulling away from a dock while it's being loaded or unloaded, Castell Interlocks Inc. (www.castell.com) of Erlanger, Ky., offers Salvo, a trapped key lock that attaches to a trailer's emergency airline coupling and an electro-mechanical lock inside the distribution center that's attached to the loading dock door. If a trailer isn't locked into place, the loading dock door won't open.

In operation, Salvo is first attached to a trailer's emergency gladhand fitting. The action releases a uniquely-coded trapped key. This key is inserted into a control panel next to the outside dock door that automatically releases the door lock inside. While the door is open, the key is trapped in the control panel.

Having experienced several close calls with unscheduled truck departures from its dock, Phil Heffelinger, director of engineering for Pennsauken, N.J.-based J&J Snack Foods Corp. (www.jjsnack.com) needed a product that would deliver a high level of reliability and low maintenance to eliminate the problem. J&J manufactures, markets and distributes a variety of snack foods and beverages for the food service industry and retail supermarkets. Among its major brands are Superpretzel soft pretzels, Luigi's Real Italian Ice and Minute Maid and Barq's frozen juice treats and desserts.

J&J tried a single Salvo unit for 90 days before purchasing the system for all of the docks at its Pennsauken facility. Since each lock is coded for a specific door, drivers can't insert the wrong key into a control panel, says John Fitzgerald, the warehouse manger. The lock "prevents drivers from backing into the wrong door and being loaded," he says, "which saves our company time and money."

Heffelinger points to another saving with Salvo locks. "Previously our dock attendants would sometimes open a door prematurely while they waited for the driver to properly spot the trailer." Since doors aren't opened until the key is turned in the lock, refrigeration costs from open dock doors are reduced.

Levelers are used in many dock operations to bridge the gap between the trailer and the dock. However, moving on a stand-up walkie or fork lift from the warehouse floor to the bed of a trailer can cause "dock shock" for operators, to use a term coined by Milwaukee, Wis.based Rite-Hite Corp. (www.ritehite.com). Rite-Hite's solution to the problem is its STR-4000 Dok-Lok Vehicle Restraint system.

The STR-4000 supports the rear of a trailer during loading and unloading. It virtually eliminates trailer drop, which is particularly severe where a trailer has an air-ride suspension systems. To prevent all forms of trailer separation, STR-4000 incorporates the company's rotating hook equipment that engages the trailer's rear impact guard at two points.

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