How to Match a Chassis and Dump Body to Handle Your Hauling Needs
Building a dump truck only requires matching up two primary pieces — a chassis and a dump body — but those two pieces have to match up in just the right way, or your investment will be a dump, in a different sense. There is plenty to consider when determining the right specs. Before sifting through all of the options, make sure you have answers to these questions:
1. What do I need from this truck?
2. What are the requirements of my territory?
3. What additional preferences will make life easier?
Once you have that figured out, the pieces to this puzzle should be much clearer.
What Are Your Needs?
The type of material being hauled dictates the type and style of chassis and body that will meet the specific demands of the material. Some are much denser, and you want a smaller cubic area otherwise you risk overloading.
“If you’re equipping the truck with a dump body, you must determine what payload you’ll need on the job, taking into consideration the weight of the crew, upfit equipment, tools and cargo and how the cargo will be loaded,” says Paul Loewer, commercial product and sales support manager of medium-duty trucks at GM Fleet.
“This will determine which model and GVWR [gross vehicle weight rating] will best meet your needs.”
Loam, sand, mulch, gravel and salt are popular to haul in dump bodies. Asphalt is not recommended as it could burn the paint off the dump body. Mud or very wet soil is also not recommended as it could leak out of the body. When transporting sand, dirt or gravel, a dump body constructed with carbon steel that has a floor free of weld seams offers the durability and efficiency needed.
“Customers should ask themselves if the dump body will be used for long hauls with few dumps or short runs with frequent dumps,” says Jim Bray, sales and marketing manager at Ox Bodies Inc. “It is also important to think about if the material will need to maintain a certain temperature. Customers looking for a dump body that can be used for short hauls and a large amount of daily dumps should consider one that’s designed to handle a variety of materials, is easy to maintain and allows for a fast unload.”
This truck may be hauling more than just haul spoils, too. For any towing application, Bray says the weight of the trailer along with the cargo being towed will be required to install the proper hitch. Also, the type of electrical and brake connection the trailer requires is imperative to proper operation, so determine the appropriate overhang on the body so it does not hit the hitch when the body is in the raised position.
Chassis Options
One of the first considerations in choosing the right chassis cab is the engine. Although engine horsepower is an important factor, torque figures more into how a dump truck will perform on the jobsite. Another consideration is whether operating the dump truck will require a commercial driver license (CDL). As long as the GVWR or gross combined weight (GCW) is less than 26,000 lbs, you do not need a CDL. That means just about any dump truck in the Class 3 to Class 5 range will be operable without a CDL. Class 6 dump trucks are on the cusp of needing a CDL, as those units range up to 26,000 lbs GVWR. The GVWR of each truck classification are:
• Class 3: 10,001 to 14,000 lbs
• Class 4: 14,001 to 16,000 lbs
• Class 5: 16,001 to 19,500 lbs
• Class 6: 19,501 to 26,000 lbs
• Class 7: 26,001 to 33,000 lbs
GVWR labels are located on the inside door jamb of most trucks or sometimes listed on the window sticker. Bodies are designed to carry “cubic yards” of material; 12 to 13K GVWs usually take a dump body with a 2- to 3-yard capacity. Those 14.5 to 19.5K GVWs can carry 3 to 4 yards of material. Classes 3, 4 and 5 are the major size options for dump bodies. As for towing, the most common solution is a pintle hitch.
Chad Semler, product marketing director for severe service, Navistar, says; “There are options for the rear frame and for a trailer wiring harness at the end of the frame, which can include a wire for the electric or air brakes. The choice there can come down to weight.”
Kevin Trainor, director of sales at Dejana Truck and Utility Equipment in Kings Park, N.Y., says trailer hitches are usually $450 to $600, underbody tool boxes are $400 and up, load covers are $300 and up and larger cab shields are $400 and up.
“There should be a well-designed trailer hitch, with a trailer plug to power the lights and brakes on the trailer, along with safety chain D rings on the hitch to act as a secondary way to control the trailer if part of the trailer or hitch were to fail,” Trainor says. “Some people will also add an auxiliary trailer brake if the trailer itself does not have brakes.”
Dump Body Options
Trainor says a good dump body has an adequate gauge of steel, usually 10 gauge, and is double walled. There should be a strong understructure to support the dump body and an adequate hoist. The dump body hoist should have the capacity to lift the weight of the body and the payload.
To establish what body will fit a specific chassis, Bray says you must know GVWR, wheelbase, back of cab to center of axle (CA) and back of cab to center of trunnion (CT) measurement, height of the cab, transmission type, after frame, clear frame and interference behind the cab. Bed capacities vary depending on length, height of sides and front and rear gates, Bray says. Configuration and design of the body will also affect the capacity. Bed capacity can be determined by obtaining the side height and front and back gate height to establish the total volume capacity.
“Options to consider include mild steel or abrasion-resistant construction, hi-lift tailgate, sloped front, desired payload, color, tarp requirements and if the body will need to be insulated,” Bray says. “The cost will vary significantly based on the features and options that are chosen. Customers should work directly with their dump body dealer to determine cost.”
There are several different designs, and the advantages of the design will vary depending upon application. Bray gives this example: a box dump is the best design for getting the most volume in the least amount of space. This design also provides even weight distribution and even distribution when spreading material. The biggest disadvantage to a box dump is the likelihood that material will get packed into the corners when dumping. Unlike a box dump, the elliptical dump will not retain as much material when dumping and provides an overall stronger design. Elliptical designs also proportion the weight of the load along the center of the dump body.
Semler at Navistar says the most important factor in building a dump truck chassis is flexibility, and he points to the regulations and weight laws that dictate what is allowed — many of which vary widely by state. How many axles are required, and how much weight is allowed on those axles? What are its hauling applications, and will it be driving down the road? He relays an example of an aggregate hauling-for-hire company that recently purchased several of its new HX models. Part of the reason the company needed these trucks was landing a contract for a big job that happened to be across the state line.
“So, he’s currently running a 6×4 and added a liftable 20,000-lb lift axle. The problem is his state has completely different weight laws, so he had to spec a different configuration,” Semler says. “Rather than that single 20,000-lb lift axle, he’s looking at three 8,000-lb lift axles. Rather than the current four-axle truck, he’s looking at going to a six-axle truck. It’s a very different configuration.”
This customer also moved from a 15-liter engine to a 13-liter engine to save weight after the additional axles added weight to the chassis. Of course, your options are potentially limitless when you choose the right dealer, as this anecdote illustrates. An experienced dealer and a flexible manufacturer will be able to both go over every detail of the truck and be sure the exact specs you need are accommodated.
“The flexibility is what’s key, but all of this adds complexity,” Semler says. “What we do is we work through our custom engineering department, get the requirements and then we sit down and start placing components and laying out the chassis in the most efficient manner to meet the requirements.”
Chris Crowell is a contributing editor to Utility Contractor.
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