Technological approaches to creating a safer loading dock

In search of automatic safety solutions

In eureka 23 we reminded readers of the risks faced by workers in loading docks and suggested simple measures to minimise the danger. Awareness and training, together with enforcement of best practice, should always be the first line of defence against accidents, but safety technology can help too.

Mark Nicholson reviews some of the technological ‘safety nets’ currently available.

Searching the internet using terms such as ‘loading dock vehicle restraint systems’, ‘dock levellers’ and ‘dock shelters’ reveals products from a wide range of manufacturers. A number of them have been chosen for this article to illustrate different approaches but many more could have been mentioned. There are systems and specifications to meet a variety of circumstances, needs and budgets, which the suppliers will be happy to explain and match to specific sites and operations.

Wheel locking in the loading dock

The Comibilok automatically places a chock against one of the vehicles rear wheels.

One of the most important safety challenges is to keep the vehicle stationary in the loading dock. It is surprisingly common for vehicles to be driven away before loading or unloading is finished. Even small movements, such as those produced by rocking of the trailer, can be enough to widen the gap between the vehicle and the dock, causing the loading platform to drop suddenly. Either way, the result is that forklift trucks, goods and staff may fall from a height.

A good example of an automatic vehicle restraint system designed to solve this problem is the Stertil Combilok. Its structure guides the reversing vehicle into the correct position and then the Combilok mechanism is activated by pressing a button on a control panel in the loading bay. Moving to the rear wheel, which is detected using a sensor, the Combilok automatically inserts a chock against it. Interlock options include a link with the loading dock doors, so that opening is not possible until the Combilok has secured the vehicle.

Devices like Thorworlds Trailer Safety Support provide a simple but effective answer to trailer tipping.

Communication can often be difficult in loading dock operations, particularly when the drivers and warehouse personnel speak different languages. Systems like Combilok overcome this by communicating with the use of lights, as everyone understands that red means stop and green means go.

Similar products include PowerLock 505 from Loading Systems and Stop Trucks from Expresso. Rite-Hite offers the Global Wheel-Lok, in which the reversing vehicle triggers a locking device which engages with the rear wheel. Again green and red lights tell the driver when it is safe or unsafe to drive away, and the vehicle is kept firmly in place until the warehouse staff unlock it.

Communication can often be difficult in loading dock operations, particularly when the drivers and warehouse personnel speak different languages.

Trailer brakes in the loading dock

An alternative approach is to make use of the vehicle trailer’s brakes to prevent it from moving. If the brake line between the tractor unit and the trailer is uncoupled, fail-safe mechanical brakes are automatically applied. As long as the disconnected brake coupling is locked in some way, it is not possible for the trailer to be coupled to a vehicle and driven away.
Castell’s Salvo system keeps the trailer brakes locked until it is safe for the vehicle to depart.

Coupling and uncoupling can be an inconvenient process in which the driver has to climb into the space between the cab and trailer. This involves working at height, with the risk of falls, trips, slips and other hazards. Don-Bur has developed a pneumatically powered Safe Coupling System which moves the coupling plate to an easily reached position, with no climbing, when the driver needs to access it.

The Salvo system from Castell combines use of trailer braking with the extra security of its ‘trapped key’ technology. A device known as the ‘SGL’ (‘Salvo Gladhand Lock’) is applied to the trailer brake coupling to keep the brakes locked. A Salvo key trapped in the SGL is released only when this procedure has been correctly completed.

This key is inserted into a Salvo control panel at the warehouse. A green light inside the building tells staff that it is now safe to open the door and start loading or unloading, while the driver is shown a red light to indicate that the vehicle must not be moved. The key in the panel cannot be removed until the workers are finished and the door has been closed. A green light then signals the driver to remove the key from the panel, use it to release the SGL and depart. (In the UK, where a different type of brake coupling is used, a ‘Salvo Susie’ lock replaces the SGL.)

Chocks and stands in the loading dock

By moving the coupling plate, Don-Bur’s Safe Coupling System allows safer access to trailer brake connectors.

The main argument against relying on more traditional methods, such as using wheel chocks to stop movement and taking away the driver’s keys to prevent driveaways, is that people sometimes forget or ignore the rules.

Castell’s Salvo range offers a chock that forces drivers and warehouse staff to follow the right procedures. The Salvo Chock contains a trapped key which can only be released when the device has been properly clamped around the wheel. Transferring this key to a control switch at the loading bay allows the door to be opened. On completion of loading or unloading, the loading bay door must be closed before the key is released again. It is then used for removal of the chock.

One further safety aid which must be mentioned, although it is not as technologically sophisticated as those described elsewhere in this article, is the trailer stand or prop. When the tractor unit is removed from a trailer there is the danger of a see-saw effect, or even a tip-over, when fork lift trucks are driven into and out of it. To date, the author is not aware of any system that automatically puts a support in place but there are certainly products that reduce the effort needed. The Rite-Hite Trailer Stand and Thorworld Trailer Safety Support are just two examples from this market.

Dock levellers

Height differences between a vehicle’s loading floor and the loading dock can produce dangerously steep gradients in the connecting platform. To minimise the slope and ensure the smoothest possible transition, dock levellers are recommended. This is an area in which there is a particularly large choice of products. Stertil, Loading Systems, Rite-Hite, Thorworld, Keeley, dockequipment.eu, Crawford and ASSA ABLOY are just some of the manufacturers.

To avoid slipping of forklift trucks, other materials handling equipment and personnel on wet surfaces, the loading dock should be weather-protected.

The most sophisticated dock levellers are electro-hydraulically operated, for high precision and efficiency with minimal effort. One choice to be made within these products is between swing lip (hinged) and extending lip (telescopic). Suppliers will advise on which type and model is best suited to the application. Factors to consider include the dimensions and load capacity required and the types of forklift truck and vehicle that will use them. These levelling systems can be interlocked with other dock systems, including door opening, vehicle restraint and warning lights, for maximum safety and productivity.

A Controlled Environment in the Loading Dock

To avoid slipping of forklift trucks, other materials handling equipment and personnel on wet surfaces, the loading dock should be weather-protected. This is another sector in which many manufacturers compete, offering a variety of ways to provide shelter as well as thermal insulation, hygiene and security. Stertil, Loading Systems, Rite-Hite, Thorworld, dockequipment.eu, Crawford and ASSA ABLOY are a few of the names you may come across in your searches.

Options include inflatable and cushion seals, as well as self-contained dock houses complete with sealing systems, secure doors and dock levellers. Considering that loading docks are seen as the most dangerous part of a warehouse, distribution centre or factory, it makes good sense to concentrate their activities and equipment into a small area where the environment and risks can be more easily controlled.