Loading and unloading in the fast lane

Alternative approaches to docking zone materials handling efficiency

We are all familiar with the sight of forklift trucks unloading lorries. In dedicated zones like loading docks, nimble forklifts or power pallet trucks take care of the job. But what if the load is extremely bulky? What if the load consists of many small boxes or even grains of sand? What if speed is the priority? Gian Schiava explores various extremes in the lorry unloading scene. Whilst looking at these solutions, he shares a few small tips to improve safety in handling today.

When conventional doesn’t get the job done

Like in so many aspects of modern materials handling, solutions can be found through automating the process. VIL, the Flemish Institute for Logistics, wanted to know more about this subject. In recent years, together with the University of Antwerp, it conducted a market study into state-of-the-art loading and unloading systems and what they could bring to both forwarders and transporters. Besides looking at the possibilities with planning software, VIL looked also at physical systems. They divided them into three categories: automated guided vehicles or AGV-based systems (industrial robots that move independently), one-shot-based systems (loading/unloading a full load in and out of the trailer in one go) and semi-automated systems (where human interaction cannot be completely omitted). The last option is especially well suited to goods with odd shapes.

Obviously, each technology has its own advantages and disadvantages, and no single system can handle every type of cargo. Company-specific processes also determine whether a system is suitable or not. One specific outcome in the report came from the business case at chocolate manufacturer Barry Callebaut, where a one-shot-based skate system was used. It automatically unloaded 26 pallets in just 10 minutes; a considerable time gain compared to the 45 minutes that manual loading previously took. According to VIL, time savings can also be achieved using belt or roller conveyor systems.

When efficiency and speed become absolute priorities, advanced systems come into play. A manufacturer of the earlier mentioned one-shot systems is Dutch specialist Ancra. Its skateloader system requires just 6 to 8 minutes for the whole loading process (depending on the required height adjustment and alignment). The homogeneous load, like crates of beverages, is first placed by forklifts onto a large shuttle system, which then slides completely into the trailer, where all pallets are placed on the floor, before the system retracts.

When efficiency and speed become absolute priorities, advanced systems come into play.

The AGV-like loading system from German company TRAPO covers the whole loading/unloading area (no humans are needed here anymore!), where dedicated autonomous vehicles carry out the loading activity in three steps. First, up to three pallets are placed side by side in a row on the stationary part of the system and aligned. This is followed by picking up and loading the row. Parallel to the loading process, the next row of pallets is formed and made available. This continuous process saves time and travelling distance. Unloading is carried out in reverse order. According to TRAPO, for a trailer 13 metres long, the loading time for 33 pallets is about 15 minutes.

Need a bigger or more peculiar example? In America, Bruks Siwertell has developed a system which picks up the whole lorry! As many bulk-carrying trucks in the USA are end-loaders, they offer two versions of so-called ‘truck dump’ equipment: a back-on and a drive-over type. With the latter, a driver enters the dumper driving forward, crossing a pit bridge and going straight onto the tipping platform, then stopping slightly forward of the backstop area. The backstop swings into position, and the driver backs up a short distance until the bumper touches it. The cab is then shut off and the front safety chain is fastened. The trailer’s back doors are opened and the driver moves to the control box and pushes the ‘up’ button. The pit bridge rises out of the way, exposing the entrance to the receiving container. The tipping platform begins to rise, and the load falls into the container. Once the trailer is empty, the driver pushes the ‘down’ button and the platform lowers. The trailer’s back doors can then be closed, the chains are released, and the truck drives away.

Stay on the safe side

These are just a few examples of interesting, innovative approaches which can improve the loading and unloading process in various applications. However, they will remain niche solutions, as payback periods can be quite long and, in addition, these advanced systems simply cannot handle the typical variety in loads. Loading processes are normally most efficient when using loading dock systems in combination with swift power pallet trucks or stackers. Having said that, this particular work environment can really benefit from various simple safety-improving devices, given that it is still considered one of the most hazardous.

One simple example: each time a forklift drives from the well-lit docking zone into the darker trailer, there is a split second in which the driver’s sight could be hindered. There are special lights on the market with a multi-articulating arm and multiple bend points to point the device in the desired direction. When there is no activity, the lights shut off automatically. Another one: most docks use dock levellers to bridge the gap between trailer and warehouse floor. When the leveller is retracted, the open door creates a risk of falling. Several suppliers have designed levellers with automatic vertical safety barriers which eliminate this risk.

There are many other rather simple solutions like this, as explored in previous Eureka articles on dock safety practices and technological aids. Until the time when docks everywhere use fully automated loading systems, we had better take advantage of the various safety solutions available today. Your employees will certainly appreciate and benefit from them.