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Photo Credit: City of Olathe, KS

Semiautomated collection—and, for some refuse companies, even manual collection—probably will never go away entirely. The concepts of reducing injuries through advances in ergonomics and maximizing efficiency to the extent possible short of full automation are not new ideas to the industry. By now, the equipment marketplace has responded to increasing demands for the highest possible operational return on investment by innovating advancements in container tippers and the containers themselves. And as manufacturers incorporate design advancements into their equipment, many refuse companies are making greater investments in productivity by entering the realm of fully automated collection.

Not surprisingly, the Solid Waste Association of North America 2007 North American Benchmarking Project for Residential Solid Waste Collection Services indicates that fully automated collection yields the highest collection service productivity, although this measurement is subject to such variables as distance and travel time associated with the trips to and from the landfill, transfer station, or waste-processing facility, and the variability in the workload that is assigned to collection crews. Also, despite the increased productivity yielded by full-automation equipment, the study indicates that increased productivity is necessary to offset higher capital costs.

Somewhat surprisingly, the study also indicates that semiautomated collection is often less efficient than manual collection because a container needs to be returned to the curb. The main driver in semiautomation, then, is worker safety. A key piece of equipment in semiautomated collection is the cart tipper.

Tippers
The refuse collector has a variety of choices in tippers. One manufacturer, Bayne Premium Lift Systems, lists several questions that the MSW operations manager can ask to make the choice of tipper easier:

• Which types of carts are used? Not all lifters will work with all carts. In general, the carts used should conform to ANSI standards Type B for domestic-style two-bar carts, Type C for European-style carts, Type D for pocketed-style carts, and Type G for automated-style carts. Many cart lifters can also dump standard size 30- and 55-gallon drums.
• How much weight will be lifted? The amount of weight to be lifted by the tipper also is predicated on the choice of cart. Each cart has a weight rating—for example, a standard 95-gallon cart is usually rated to hold up to 350 pounds. This question is especially important when weight expectations are on the high end. When equipped with the proper actuator, some cart tippers can lift up to 700 pounds.
• What is the sill or hopper height of the refuse collection vehicle? Lifters are available with various arm lengths because not all models of refuse collection vehicles have the same sill height. Longer arms are used with higher sills so that when the lifter is mounted in the correct position on the sill, its faceplate is properly set up to connect with and dump the cart. Lifters picking up domestic two-bar carts require a clearance of 34 inches from the ground to the lifter saddle, where the cart bar rests. European-style carts require a clearance of 38 inches from the ground to the top of the lifter’s comb assembly.
• Does the refuse collection vehicle have a winch, reeving cylinder or commercial container bar? Not all lifters work properly on rear-loaders equipped with commercial container–handling devices. Modifications may be required to ensure that a commercial container does not rest on the cart lifter—and thus damage it—when it is being emptied. In addition, the lifter must be able to rotate within the opening between a commercial-container bar and the hopper.
• Is a cylinder lift or one that uses a rotary actuator better suited to the operation? Two basic kinds of cart lifters are available: One uses a hydraulic cylinder to lift the cart, and the other uses a rotary actuator. Cylinder lifts tend to be less expensive up front and suit semiautomated carts in particular. Lifts using rotary actuators are designed for greater durability and the ability to lift heavy weights at lower system pressures, as well as the ability to pick up a wider range of containers.
• What kind of rotary actuator does the tipper use? The tipper’s actuator provides the rotation needed to lift and dump the cart. Two kinds of actuators are prevalent: helical and dual rack and pinion. Helical actuators may cost less initially, but replacement parts are reportedly more expensive on average. Dual rack-and-pinion actuators have fewer parts and may be easier to repair.

Collection of yardwaste is semiautomated in Olathe, KS, where residents purchase the carts used in a new, voluntary program, notes Darren Gilbert, assistant solid waste manager. The carts are replacing yardwaste bags that previously were used for clippings and bundle brush.

Gilbert says that semiautomated collection will always be used in Olathe, largely because of the new yardwaste program. The city has 11 routes, which are identical for trash and recycling, and yardwaste. One of the city’s 12 fully automated trucks handles a trash/recycling route, and two of a total of eight tipper-equipped rear-loading trucks and tipper-equipped side-loading trucks handle a route for either trash/recycling or yardwaste.

Photo: Otto Environmental Systems

The tippers use rack-and-pinion rotary actuators and are designed to position containers deep inside the hopper to prevent spillage and to increase the number of dumps before packer-blade cycling is necessary. Gilbert reports that smooth operation is an aspect of the TL Series tippers that minimizes both spillage and container damage. “It’s pretty important when the cart’s going up; you don’t want something that’s vibrating so it falls off,” he says. “If you have something that jerks, you can damage the cart, or—worst-case scenario—it can hit the ground, and then you’ve got trash all over the street.” Another benefit is a self-greasing bearing that reduces the need for maintenance as well as the potential to forget to lubricate the bearing.

On its rear-loading trucks, the city uses Bayne’s BTL Series, which also uses the rack-and-pinion rotary actuators and self-greasing bearings at the main pivot points. This tipper is specifically designed to offer greater ground clearance for rear-loading applications to reduce damage on uneven terrain, such as alley entrances.

Collecting refuse from carts bunched closely together and the ability to sometimes lift heavier containers—and thus reduce the number of necessary collection trips to some customers—are additional reasons why semiautomated collection remains a viable technique, according to Perkins Manufacturing Co. Two tipper models in particular, the D6080C Heavy Duty Rotary TuckAway Lifter and D6220 TuckAway Cart Lifter, are equipped with features to maximize collection efficiency.

The D6080C has been available for about 20 years and has gone through several evolutions. The unit’s picking and dumping cycle time is about six seconds. The TuckAway design, with which the unit recesses under the hopper, is intended to protect the tipper from damage and prolong the life of equipment. The TuckAway’s “BreakAway” feature reduces damage to the actuator in the event of a collision or bottom-out.

The D6220 is similar to the D6080C but has a more compact design that allows greater ground clearance. It suits many trucks that are not compatible with the D6080C.

Containers, Wheels
Manufacturers would tell you that not all containers are created equal. What a refuse company’s customers might consider commodity items with few differentiating features are known as anything but that by the professionals who pick up the refuse. As the level of collection automation has increased in recent years, manufacturers have increasingly focused on container durability and ergonomic design.

Photo: Toter Inc. Toter Inc. makes carts that suit semiautomatied and automated collection alike.

Realizing that full automation is highly productive yet rough on containers, the city began replacing its residential trash containers with Otto Environmental Systems’ Edge residential carts in January 2008. The containers are designed to withstand the extreme forces exerted by semi- and fully automated collection equipment. A design feature that is included to accommodate automated systems with grabber arms such as those used in Scottsdale is the elimination of “corners” that tend to compress during lifting. Instead of a lift pocket, a.k.a. bib or pouch, the container is also available with a smooth ridge around the top of the cart base, and it is also available without a catch (or lift) bar—a feature designed for semiautomated collection.

By the end of winter 2008, Bennett reports, not one of the containers had cracked, a fact he attributes to the containers’ design and use of injection-molded plastic. “The thing in Arizona is that you not only have the heat but also the cold,” he says. “These containers have to survive extreme heat—you’re talking 130 degrees when it’s out in the sun, and in the winter it’s below freezing, so they have to stand up to a lot. So far, these containers stand up to that test.”

Photo: Bayne Machine Works

The rear-loader counterpoint to the TL series by Bayne Machine Works is the BTL Series, which is designed with greater ground clearance for rear-oading applications. Shown here is a dual configuration for high-efficiency collection.

Bennett says another beneficial feature of the containers is its ease of assembly. “One big thing is that, when they’re delivered to us, they’re pretty much fully assembled—all we have to do is snap on a wheel and the axle,” he says. “That’s important because when they’re delivered there’s usually around 500 cans; they come stacked in rolls of 12, and you just have to pull that stack down and assemble the containers yourself. You don’t have to pay extra people to come out here and assemble them—the lids are already on, and you snap on a wheel. You don’t have to carry extra parts, screws, et cetera. In the past, we had to assemble the lid and the axles and it was big process and now we can assemble them out in the field and maybe take 30 or 40 out on a route.”

Another city that has gone to fully automated collection almost exclusively is Austin, TX. Dale Johnson, warehouse supervisor for the city of Austin, reports that the city converted to semiautomated collection in 1993 to save workers’ backs and then began transitioning to fully automated collection of residential trash in 1999. Currently, he estimates that about 70% of 181,000 customers’ residential collection there is fully automated. The remaining 30% of customers who require semiautomated collection mainly live in student housing in this major college town, the home of the University of Texas at Austin. These areas tend to be crowded and curbside refuse is packed tightly together, making fully automated collection difficult, Johnson explains.

The city uses Toter Inc.’s EVR I and EVR II carts, which can be used for both fully automated and semiautomated collection. One differentiating feature in the carts that the company promotes is its patented, stress-free Advanced Rotational Molding technology, providing greater durability.

Another differentiating feature, according to the manufacturer, is the fact that the steel lifting bar is sealed on the interior of the container with a double wall; this keeps out moisture and insects that can damage the container and reduce its working life. Additionally, the bar rotates on its own axis, providing play that increases the bar’s durability. Noting that many refuse companies and municipalities replace their fully automated lifting equipment or tippers several times during the life of containers, these carts are also said to be compatible with any US collection system.

“These seem to hold up and work really well and meet our needs,” Johnson says. “We really don’t have cart failure at all—we’ve got some containers out there that we’ve been using since 1993, and I expect that we’ll still get a few more years out of them.”

Another manufacturer, Rehrig Pacific Co., offers universal HuskyLite Roll-out Carts, which are available in capacities of 20, 35, 65, and 95 gallons and have a one-piece, molded-in handle and a built-in foot tilter for maneuverability. The top lip is reinforced, and molded-in lift points are designed for strength and rigidity. The carts are shipped with the lids already attached and the wheels snap on for reduced assembly time. The manufacturer uses injection molding to add extra reinforcing material in load-bearing points and high-wear areas. The resulting rigidity is incorporated to prevent bending and pinching, a particular problem in fully automated collection. The carts are also designed with smooth interiors to eliminate catch areas. Ergonomic features include large, heavy-duty handles and an integrated foot tilter on the company’s 65-and 95-gallon carts. A ground-hugging base is designed to keep the units stable in high winds and on uneven terrain.

Rehrig Pacific’s plastic 25- and 32-gallon cans suit manual and fully automated collection alike. The company points out that they also can be used for any type of refuse. Their relatively greater height compared with recycling bins, for example, makes manual or semiautomated collection easier on workers. To compensate for a taller profile, however, the bottoms of the cans have additional weight. Additional ergonomic features include large spaces between the handles and the sides of the cans, as well as drag rails that allow workers to drag them across the ground. Injection-molded HDPE resin is used for superior durability.

Like the containers themselves, wheels on rollout carts are anything but a commodity. Roll-Tech LLC specializes in rubber-tread wheels for rollout trash containers. The advantage of rubber wheels, the manufacturer notes, is that of less noise during maneuvering. Durability is an additional benefit, according to the manufacturer; unlike plastic units, the rubber wheels keep moisture out and prevent freeze-thaw deterioration prevalent in northern climates. The company also promotes the eco-friendly aspect of the recycled crumb rubber and recycled plastic wheel hubs.