With all landfills there are slopes, soft underfoot conditions and weather. Articulated trucks are best suited to work in these challenging conditions.
By Clay Layne

Landfills are a busy and dangerous environment, and industry equipment manufacturers are always striving to make the machines safer, especially in such environments. Articulated trucks are used extensively in the landfill. They are used for cell development, hauling cover soil and moving rock or other material for haul roads. Just about every landfill has an articulated truck or two. With all landfills there are slopes, soft underfoot conditions and weather. The articulated trucks are best suited to work in these challenging conditions. The design of the truck with its oscillating and articulating hitch is to keep all six wheels in contact with the ground and provide traction upgrades and in heavy rolling resistance conditions. There are two types of articulated trucks: a standard tipping machine and an ejector. Because the slopes, soft underfoot and inexperienced operators are a potential safety hazard, some of these issues have been addressed in a new series of articulated trucks.

Standard Tipping Articulated Trucks
The Articulated Truck known as the tipper style is the most common Articulated Truck that you will see in the Landfill. The tipper dumps its material by raising the truck bed via two hydraulic cylinders until the material slides out of the truck bed. The operator will identify where the material needs to be dumped. The operator will then visually inspect the area to ensure its level, so he can safely raise the bed to dump the material. If the dump area is unlevel or the underfoot is to soft, then this could cause a tip over when the bed is fully raised to dump. Once the operator determines it is safe to dump, the truck will be aligned to the dump area and shifted to Reverse. The operator drives in reverse to the dump point, the truck is then placed in Neutral, the park brake or wait brake is applied, and the bed is fully raised to dump the material. Once the bed is fully raised, the operator will pull forward to allow all of the material to slide out of the truck bed, the operator will then lower bed and drive away to the load area.

Additional features to look for include:
Assisted hoist ontrol: Fast intuitive hoist control allows for faster cycle times and less operator control movements. Auto and manual operation that gives flexibility for the operator to choose what system they prefer. Automatic system neutralizes transmission, applies wait brake and hoists the body to the maximum angle at full RPMs
Assisted hoisting control: Manual or fully automatic, activated with the flick of a switch. Automatically applies brakes, and sets the transmission to “N”
Economy mode: Can give an average of 5 percent fuel consumption reduction on some sites.
Speed limiting: Machine speed limit can be instantly set or un-set with the press of a button.
Quieter cab: Targeted noise reduction of 7db to 72db in cab.
Advanced automatic traction control: Monitors underfoot conditions, and proactively applies diff locks to prevent wheel spin.
Access lights: Illuminates the steps and hitch area for the operator, with ground level switch.

CAT 740 EJ Articulated Truck moving dirt in a landfill.
Photos courtesy of Caterpillar.

Ejector Articulated Trucks
The ejector articulated truck is different from the normal tipper-style because it does exactly what the name says: it ejects material out of the rear of the bed. A four-stage cylinder connected ejector plate pushes the material out horizontally instead of raising the bed in the air and risking a tip over.

An ejector-style truck will do everything the tipper-style truck will do and has a few more advantages with it. The ejector can back up and dump in a pile from a stationary position allowing the truck to pile material up like the articulated tipper truck, it can dump on a slope while traveling or stationary so you can dump material in those not-so-great situations without worrying about tipping over, it can spread material evenly across a haul road, and it can spread material going forward or in reverse, allowing the truck to spread cover soil on the working face and never touch any exposed waste, speeding up the end of day operations.

With the ejector truck working in the landfill and spreading cover soil evenly on the ground, it makes less work for the dozer. The dozer does not have to push and spread the whole pile. The material is already spread in a thin layer and the dozer can fine grade to the normal six to eight inches of cover soil faster than spreading a pile of cover soil. This allows for less wear and tear and less fuel burn on the dozer because it is not working as hard due to the ejector being able to spread the cover soil.

Productivity is also higher with the ejector since you can dump on the fly and you do not have to wait for the bed to raise and lower. The dump times are faster, allowing more loads per day.

Stability Assist
One of the newest safety features in the articulated trucks is stability assist. This feature is extremely helpful in articulated trucks that raise the bed to dump material. When the bed raises, it changes the center of gravity of that truck and if it is leaning too far, the bed will tip over. Stability assist warns the operator if the machine is approaching an unsafe angle and it stops the hoisting of the bed if the truck is at too much of an angle. The system monitors angles of the tractor trailer and grade independently of each other. This system helps in the prevention of tractor and trailer roll over events. The system will also give an audible alarm warning if the operator is running on a side slope greater than 15 percent. This warning is designed to let the operator know if the truck is in a potentially unsafe situation and they need to adjust the machine.

Additional Features
Some other features of newer style articulated trucks that landfill operators should consider for efficient and safe operations are:
Haul road maintenance: The ejector keeps moving and spreading material in a thin layer, making it easier for the support machine to grade the road. The ejector truck can also stop and eject as little of material as needed to fill a hole in the road.
Combined hoist/transmission lever: Incorporates park brake/introduces assisted hoist control with both auto and manual modes. This allows for up to 50 percent less operator actions required.
Seat belt indicator: Audible and visible alert if the operator is not wearing a seat belt.
Operator presence switch: Machine will not start if operator is not in the seat.
Terrain based throttle control: Smoothens throttle input over rough terrain to improve ride quality.
Advanced traction control: Proactively applies differential lock to prevent wheel spin.
Directional shift protection: Protects the powertrain when quickly moving from R>F or F>R.

Some of these safety enhancements combined with the safety of the ejector truck show the commitment to making safety a priority in any industry. At the end of the day, we all want everyone to go home the same way they came to work.

Reducing the Risk
Articulated truck tip overs at landfills is one of the biggest safety concerns at many of the landfills I visit. Address those concerns through a combination of operator training and the right equipment. While the ejector truck does not replace operator training, it does greatly reduce the risk of truck tip overs in the landfill. Increased safety and production is a winning combination. | WA

Clay Layne is a Waste Application Specialist with Caterpillar (Peoria, IL). He started working at Caterpillar in 2008 as an operator at the Peoria Proving Grounds working with Engineers on Research and Development of Caterpillar Machinery. In 2011, Clay moved to the Edwards Demonstration and Learning Center.It was here that he started working with Tom Griffith in the Waste Industry. He has been conducting onsite operator training for all of Caterpillar’s Waste Customers since 2012. Clay can be reached at 309-675-8486 or e-mail layne_clay@cat.com.