The bulk commodity transport industry ranges from woody biomass to municipal solid waste. These commodities are best carried in Live Floor trailers equipped to maximize the volume of materials being hauled and the ease of unloading over uneven terrain. Live Floor trailers built to be forklift compatible can also be utilized for hauling palletized loads, Gaylord boxes, and super sacks. The following is the quick guide on floor choices for various bulk materials.
Static Friction and System Function
Live Floor systems all utilize the basic principle of static friction on aluminum slats to move bulk materials. By engaging hydraulic cylinders physically attached to cross drives under the trailers, the bulk material is conveyed out the rear of the trailer without the need to lift the trailer bed. The cross drives are secured to the aluminum slats on top, which ride on High-Density Polyethylene (HDPE) bearings and 1-inch-by-2-inch subdeck for stability. This subdeck is secured to the frame of the trailers by the cross-members and longitudinals/bottom rails for the greatest support of the frame. As the hydraulic cylinders move back and forth in sequence, the subsequent slats above move the pile using static friction toward the rear of the trailer to unload. Then, the slats retract under the pile, breaking static friction one series at a time to start the cycle all over again until the trailer is unloaded. By reversing the flow of hydraulic oil, the system can also be utilized to load material into the trailers in the reverse method.
Pressure and Flow
Hydraulic pressure and flow are the determining factors of pushing capacity and speed at which the system works. Depending on the size of the hydraulic drive, this pressure will generate enough force to convey a load weighing between 7.5 and 45 tons.
The speed at which a Live Floor operates is determined by the flow rate of the hydraulic pump. The more flow the pump creates, the faster the system will unload. However, there is a point of diminishing return on the flow rate. It is possible to have a floor system running so fast that it doesn’t maintain the static friction on the pile and will slow down the unloading time. It is also possible to have a floor system moving so fast that it creates a jackhammer effect on the entire trailer, causing premature fatigue and failure. To increase system longevity and functionality, a Live Floor system is recommended to run optimally at 30 GPM.
Integration with the Trailer
The trailer and Live Floor System must be joined to create the optimal strength for the system and ease of use. Hallco utilizes either a perimeter or center frame mounting system specifically built to match the trailer manufacturers’ specifications. These custom-built frames require no additional cross-bracing and marry up the trailer and hydraulic drive into a cohesive unit.
Cross-members on the trailer run perpendicular to the length of the trailer and tie the bottom rails to the longitudinals. To further strengthen the Live Floor trailer, Hallco utilizes 1-inch-by-2-inch subdeck that is fastened to the cross-members by welding or a mechanical fastener. The 1-inch-by-2-inch subdeck supports the slats above and locks the cross-members below into a cohesive unit.
On top of the subdeck sits the High-Density Polyethylene (HDPE) bearings that minimize friction between the slats and the subdeck. These bearings are wear items that also offer further support for the aluminum slats and load above them. The more bearings, the more support the load has. It is important to match the number of bearings with the type of material you are hauling based on the tonnage of the commodity in the trailer. Lighter products, such as wood shavings, require fewer bearings than the heavier commodities, such as compost and MSW.
Compost, Lawn Waste, Wood Chips, and Mulch
For wood chips, mulch, compost, lawn waste, and organics, two considerations must be addressed: 1) cleanout of the trailer to reduce operator sweeping, and 2) wear versus weight of the floor system. Wood products and compost/soil products require more surface contact to properly unload. Consider using a flatter floor like the Hallco Standard Floor. This floor offers the greatest contact surface with the material and provides the best cleanout of the finer materials. The industry top choices for most wood and organic products are a flat Standard floor in 3/16-inch, 7/32-inch, or 1/4-inch thickness. Floors with ridges and valleys will require more sweeping by the operator or the use of a “sweep” wall to properly clean it out.
Thicker floors are slightly heavier but offer a longer life of the floor slat. Since the rear of the trailer contacts 100% of each load and the front of the trailer floor only contacts less than 20% of each load, consider added wear strips to the rear 2–4 feet of each slat to increase the life of the slats. Most slats can be turned halfway through their life to further extend the life of the floor system.
Food Scraps and Wet Organics
For wetter products such as wet MSW collections, food waste recycling, and compost in wetter environments, a leak-resistant or leak-proof floor system may be the best option. If you are top-loading your wet materials, consider using a floor with a good continuous triple ridge like the Hallco Narrow-Leak Resistant Heavy Duty or W-Floor for leak-proof applications. Also, for leak-proof applications, consideration must be given to the placement of the hydraulic drive. Consider a drive unit mounted outside the trailer body to the front of the trailer for optimal serviceability and leak-proof protection.
Standard MSW/Mixed Wastestreams
For the top loading of MSW, a floor needs to have impact ridges built into the aluminum slats. They are continuous and run the length of the trailers’ working surfaces. These ridges protect the floor system from heavy items, such as construction debris, automotive parts, appliances, etc., from being dropped from above. Typically, these double- and triple-ridge floors come in 1/2-inch-thick and 3/4-inch-thick, with the heaviest coming in at 13/16-inch-thick. Wear strips can be added to the rear and front of the slats to further extend their life.
Rear Compactor Loading
For single-stream recycling loaded with a compactor, the best option is a flatter floor. Since there is no impact of product dropping from a high position, the floor will be best as a standard flat floor. The slat thickness ranges from 1/8-inch- to 3/8-inch-thick. This flat floor enables the material to easily slide into the trailer. A flat floor also provides a better cleanout of finer or compacted materials because of the greater surface contact area. This reduces the number of times a driver must climb into the trailer to sweep out the floor. Keeping operators out of the trailer will also reduce the risk of potential fall injuries. It is almost necessary to have wear strips welded to the floor slats with compactor loading to reduce wear on the slats at the rear of the trailer.
Today, the recycling market seems to be making a move back from sorted to a single-stream. What is considered “milk-carton” recycling can be loaded on a very flat standard style floor. There is little to no risk of impact hazards with these commodities. If glass is in the recycling stream, precautions must be given to protect the seals in between the aluminum floor slats. Glass will quickly wear away at any exposed seals and then the trailer will begin to leak. The Hallco narrow leak-resistant floor offers the best choice with the seal tucked under a 3/8-inch overlap, providing the best protection of the seal and clean-out of the floor.
Choosing the right floor for the job can seem overwhelming. Knowing the materials being hauled, in both directions if there is a backhaul, is the first step in making the choice. No one floor fits every application. The ability to utilize your trailer for more than a single type of load will provide a faster return on investment for your purchase. Being able to utilize fork-trucks on the floor will also provide another tool in your arsenal and expand your ability to haul palletized goods. When a loading dock isn’t available, a floor system can be run in the “LOAD” mode to move the pallets forward in the trailer.
Versatility, safety, and strength are key attributes of the Live Floors systems. Getting the most out of them is easy when considering all the possible ways they can be used. Speak with your trailer dealer or a Hallco Representative for which floor system will work best in your fleet.