A variety of factors can influence the productivity and longevity of the dump trailers in your fleet. To ensure they deliver the performance and service life you expect, it's important to determine the appropriate setup for the application, and then operate and maintain the trailers for both optimum efficiency and longevity.
Long and short of it
While dump trailers and tractors offer advantages over a conventional dump truck in many applications, properly setting up a tractor/trailer combination is more important than you may realize. Whether you run end dumps, side dumps or bottom dumps, matching the truck to the trailer influences productivity.
"Matching a truck to a trailer is really something that deserves more attention than it is often given," says Charlie Wells, East Mfg.
Many contractors own a variety of trailers, ranging from lowboys to dumps, and try to pull them with the same trucks. But this is changing. "It is a growing trend that people marry trucks and trailers together because of the overall efficiency gains," says Jim Ladner, national sales manager, Landoll.
Consider a 39-ft. dump trailer. To maximize the load in many parts of the U.S., you need to follow the Federal Bridge Formula. "To get your Federal Bridge, you need 51 ft. from the front axle to the rear axle," says Ladner. "That is the outer bridge. The inner bridge is the front drive axle to the rear axle of the trailer. That has to be 36 ft. With those two lengths, you can gross 80,000 lbs."
The closer to these measurements, the better. "It doesn't help if you are 1, 2 or 3 ft. longer," Ladner states. If you use a sleeper cab, you may be 5 or 6 ft. longer. "You take away from payload and pull that extra weight down the road all day long. If you can operate within the Federal Bridge with a truck that has a 190-in. wheelbase, why operate a 250-in. wheelbase? You lose maneuverability. You are losing payload and increasing cost of ownership."
Most construction operations want short trailers. "You have to keep short for maneuverability in the yard," Wells states. "That is when you find that a shorter multi-axle dump trailer is better."
Longer 39- or 40-ft. dump trailers are typically configured as five-axle rigs — three on the tractor and two on the trailer. But when you move toward shorter trailers, you need multiple axles to meet federal and local weight regulations. The length of the trailer influences the best tractor configuration.
"A general rule of thumb is a short wheelbase tractor, defined as a 185 in. or less wheelbase, is optimum with a short multi-axle (three or more axles) dump trailer," Wells states. "So you want a long wheelbase with a long tandem dump trailer and a short wheelbase with a shorter, multi-axle dump trailer."
But there are setup considerations with multi-axle trailers. "The fifth-wheel height becomes an issue because the closer the trailer can run to level, the easier it is to set ride height on suspensions and get the axles to equalize," says Wells.
A challenge with longer five-axle rigs is getting weight transferred to the steering axle. "Any time you can spec heavy components on a truck as far forward or a set-back axle, that is more optimal," says Wells. That means less weight has to be transferred to the steering axle.
Shorter tractors can really help with weight transfer. "That front axle is closer to the load the shorter the truck that you use," says Ladner. "A set-back axle naturally moves that axle closer, so it is a good choice. You always want to take maneuverability into consideration. You are always trying to get into and out of places and the shorter tractors and shorter trailers just give you enhanced maneuverability that allows you to go places that you can't take longer vehicles."
The wheelbase of the tractor directly impacts the best trailer setup. "When a customer looks at spec'ing a dump trailer, I will ask if he is trying to match it up with an existing wheelbase truck," says Wells. "If you have a long wheelbase truck, the optimum is a long tandem dump trailer." But you must consider the application. "You are not going to use a 39-ft. tandem-axle trailer to do paving work. So you have to sift through the information and come up with the best spec."
You also need to consider trailer weight. "During the last decade, heavyweight trailers became more popular because they were cheaper," notes Ladner. "They were cheaper to buy because you don't use high-tensile-strength steel and structures that cost money to keep weight out of the trailer. Today, I see a transition coming back in where payload is very important."
Sales of heavy weight trailers are starting to slow down. "The customer is looking towards the actual payloads that the trailer is capable of hauling" says Ladner. "If a trailer weighs 2,000 lbs. less, in a 10-trip haul, you move 10 tons more in the same day as the heavyweight trailer. That is where that lightweight trailer starts to pay benefits."
Abuse shortens life
Most dump trailers will provide trouble-free operation provided they're not abused. "A dump trailer is not all that technical," says Ladner. "If you take care of maintenance items, the only other thing is abuse."
Rough roads are a good example. "It might be a road where you can sit in the seat at 20 mph, but you have to tighten your seatbelt when you are driving 35 or 40 mph due to the road condition," Ladner comments. "There are going to be drivers that drive at 35 mph and drivers that drive at 20 mph. Those issues always surface in product repairs."
That brings up the point of driver training. "You need to have basic training for drivers so they know what you expect as an owner," says Ladner. "Today, these trucks and trailers become very expensive. You are just trying to maximize that life cycle."
Trailers do have limits, even in areas where you may not be travelling on weight-restricted roads. "Don't overload a trailer," Ladner emphasizes. "The limit is on the vehicle identification plate we put on every trailer." This includes the gross vehicle weight rating (GVWR) and gross axle weight rating (GAWR). "Those are the two primary components that are weight restricted. Everything else is designed to the maximum numbers on the data plate."
"Our trailer actually has more yard capacity than it can legally haul," Ladner asserts. This accommodates the different densities of various materials. "How many square inches of capacity you need does depend on the materials you are moving."
Don't overlook maintenance
After you choose the right trailer, you need to keep it working. Downtime is typically caused by a lack of maintenance.
"[That includes] everything from not putting a nickel's worth of grease in a joint to not washing the equipment," says Wells. "Corrosion is a big problem, especially where steel components are bolted to aluminum components and you get galvanic corrosion." As such, it's important to keep these areas clean.
Don't forget to periodically drain the air tanks. "If you get condensation in the air tanks, the next thing you know, it is affecting valves and other components," says Wells.
Before starting your work day, perform a pre-trip inspection. "Look at the tire inflation," advises Wells, "If it is a spring-type suspension make sure none of the springs are broken." Visually check that the bolts in the torque arms are tight. "If you are starting out in the morning in a garage, look to see if there is any fluid on the floor anywhere." Make sure there isn't a wheel leaking. "From that point fire it up and check lights, and make sure the brakes are actuating."
Also make sure tires are properly inflated. "Tires are a major cost item. There is more awareness of tire pressure today," Ladner comments. He notes that Landoll offers a tire inflation system that ensures air from the main air supply of the truck is constantly fed to tires to maintain proper pressure. "It is a good investment."
Simple steps prevent rollovers
End dumps are among the most common types of dump trailers. There are three basic categories of end dumps: frame, frameless and quarter frame.
"A frame dump trailer is probably about as simple as it gets," says Wells. It is very low maintenance. The quarter frame, on the other hand, probably requires the most maintenance. "It has six pivot points that make it work. Every time the body is raising up and down, every one of them is going through some kind of friction."
A frameless dump trailer also requires more maintenance because there are more moving pivot points. "On a frameless, you have a set of draft arms. You have a center pivot point," Wells points out. But all the dump trailers perform well if you keep them greased and washed.
However, you need to follow a few simple procedures to ensure safe operation. "When it comes to loading, make sure the load on an end dump is centered from side to side," says Wells. An off-centered load will push the weight to one side of or the other when the body is being raised up, increasing the potential for a tipover. "It is hard to get it perfect, but part of the job of the driver is to make sure the loader is putting the load as close to the middle as possible, not just throwing it up there."
In addition, select the unloading site carefully. "Probably the most important part of the unloading site is choosing a place that is level, where the trailer itself will be level," Wells stresses. "In our experience, we have found that trailer attitude is probably a little more important than truck attitude. While it is important to have both level, if one is really critical, it is going to be the rear end of the trailer."
The truck and trailer cannot be jackknifed. "It needs to be in line," says Wells. "That is especially important in a frameless. Because of the way a frameless operates, it pulls the truck towards the trailer in the dump cycle."
A level, smooth, hard-packed surface is ideal. "But there are times when you must compromise," Wells acknowledges. "Then you should watch the base. Put the pump into gear and raise the body up. Watch it the entire time to make sure that if it starts to lean, you let it down and reposition the body." Never move a dump body in the raised position.
Wind speed and direction should also play a role in choosing the best unloading orientation. "A raised trailer is like a big sail on a sailboat," says Wells. "If you have a 30-mph crosswind, it can blow it over. So wind direction is important. And look above for power lines or any other obstruction."
Many times, the load does not completely empty. "We recommend the body is lowered and the trailer is pulled up 8 to 10 ft. and then raise the dump body again," Wells advises. "We know most operators don't do that, but that is the recommended practice."
A poorly maintained end dump can also contribute to rollover risks. "The rear hinge is the most important component on a frame dump trailer," Wells states. As the body gets raised and lowered, all of the weight is transferred from the front to the rear. "At some point the rear hinge carries almost the entire load. It takes some wear."
If this component is ignored, that wear will result in slop. This affects dump stability. "If the body is raised up in the air and that rear hinge is loose, 1/16 in. movement back there can create a lot of movement when a 30- or 40-ft. body is raised," Wells points out. "It is very important to keep the slop out of the hinge."
And even though they should been have checked during the pre-trip inspection, get out and check tires again at the dump site. "You may have started out okay, but that doesn't mean you are okay at the dump site," says Wells. Tire inflation issues can increase the chance of a rollover.
