Debra Schug, Contributing Writer
In any material handling operation, the loading dock area is one of the busiest and most dangerous places in the facility. However, many of these inefficiencies and accidents are completely avoidable with proper design of the docking. A solid understanding of the basic equipment, including dock levelers, vehicle restraints and sealing systems, can help make operations run more smoothly. This article will take a look at these three components of loading docks and explore the different categories and the applications for which they are best suited.
To help prevent accidents around the loading dock area, using a proper vehicle restraint reduces the chances of trailer separation accidents, which can cause serious injuries and damage to assets and equipment.
“Securing a trailer to the facility is the first step in creating a safe and efficient loading and unloading process,” said Walt Swietlik, Director of Customer Relations & Sales Support for Rite-Hite.
There are many different kinds of restraints. The most basic type is a “wheel chock,” which can be utilized with or without a light communication package. Using this type of communication system is considered a best practice for loading dock designs.
“Not only do sensors and lights communicate dangers, they enhance efficiency as workers are more confident in what’s happening around them,” said Swietlik.
Vehicle restraint systems can be manually or automatically activated by the trailer contacting the restraint’s trigger device. They restrict movement of a transport vehicle by engaging the rear impact guard (RIG) or actual wheels of the transport vehicle.
“For facilities that handle mostly OTR (over-the-road) trailers or have a wide range of trailers serviced at their loading docks, we’d suggest using a restraint that wraps around the RIG,” he said. “There are some restraints that have the ability to secure trailers that have obstructed RIGs.”
Another type of restraint system utilizes wheel-based restraints, which are located on the ground and lock wheels into place. This type of system is most commonly used in operations that handle liquefied material, dry bulk cargo or gases.
“These loads can be extremely heavy, making it even more important to secure at loading docks,” said Swietlik. “Restraints on the ground that lock wheels into place are much more effective than wheel chocks, which were commonly used decades ago.”
Loading Dock Levelers
A dock leveler allows the movement of materials between a vehicle and a building by bridging the gap and height difference between the dock and the trailer. This equipment also compensates for the up and down float of the trailer bed during loading and unloading. After a trailer is properly secured to the loading dock, operations should use a dock leveler that is engineered to provide a smooth transition from facility floor to trailer bed and back, said Swietlik.
A dock leveler includes a deck, which is hinged along its rear edge; and a lip, which is hinged at the front of the deck. When the operator engages the dock leveler, the ramp is raised, and the lip swings out. Once the lip is fully extended, the operator lowers the ramp until the lip rests on the truck bed.
Systems dock levelers fall into three main categories:
Pit style: Probably the most common loading dock set up, this leveler is installed in a pit formed in the loading platform. The recessed pit area allows for a range of trailer bed heights, which makes them versatile.
Vertical: A vertical leveler is a dock leveler that is stored in a vertical position. This allows the leveler to be stored inside the building and enables the dock door to be closed on concrete, instead of across the leveler, as is in the case of a pit leveler. Because this style allows for better environmental control in buildings, many facilities that are sensitive to sanitary operations, such as food and beverage, pharmaceutical and cleanroom-based operations, use vertical storing levers as do operations that need to thoroughly wash down their loading docks.
“Vertical levelers also are much more sanitary as they allow overhead doors to close directly onto the floor and eliminate pit areas that are notoriously difficult to clean,” said Swietlik. “This drive-through application enhances security, as well.”
The term is referred to as “drive-through,” because the trailer doors aren’t opened outside nor are trailer security seals broken, but the doors open into the building. Vertical levelers are typically pit- or shelf-mounted and hydraulically operated.
Edge of dock (EOD): This type of dock leveler is usually mechanically operated but may be pneumatically or hydraulically operated. EODs are found mounted on the exterior wall of a building but may also be pit-mounted. They are more ergonomic than dock plates, but more suited for low-volume facilities with smaller budgets that only service standard over-the-road (OTR) trailers, said Swietlik. The EOD has a limited vertical operating range and is better for applications where the transport vehicle bed is at, or very near, the floor level of the building.
Dock Seals and Shelters
Dock seals and shelters are two types of methods to protect the interior of facilities from the outside elements at the loading dock. Seals are often foam-filled and covered by fabric, which is compressed and seals against the back of a trailer. This type of device is typically applied with smaller door openings. However, not all seals and shelters work for every loading dock application.
“Determining the best products that work in concert with one another to properly seal the dock opening is essential in maximizing energy and cost savings,” said Swietlik. “While foam, compression-style dock seals generally offer a great deal of energy efficiency, even highly durable fabric can suffer from significant wear-and-tear due to constant friction.”
Plus, seals can prevent some trailers from accessing the dock area because the foam, and fabric can protrude into the trailer during compression, he added. Seals can achieve up to 90% efficiency when controlling air flow at the dock.
“Dock shelters, in contrast, tend to offer greater access to loads, but unless the right model is selected, energy efficiency tends to be lower than that of a seal,” said Swietlik. “It’s essential for facility managers to find a system of products to fill these gaps around the loading dock perimeter with a consistent seal along trailer sides, tops, corners and underneath the leveler.”
The proper equipment used in loading docks for the appropriate application can help boost the overall safety and efficiency of loading dock workers. To achieve this, operations should think beyond a single piece of equipment, stated Swietlik, but focus on a system of products that can deliver safety, efficiency and security.