1. A mining dump truck combination body for the transport of materials of different densities, the body having a front wall, opposed side walls, and a longitudinal floor and the body being mountable to a truck chassis at pivot points under the body, the floor comprising:
- a first transverse forward section disposed to create an angle of between 5 and 26 degrees from the horizontal when the body is in a payload transporting orientation;
a second transverse intermediate section disposed to create an angle of between 6 and 26 degrees from the horizontal when the body is in a payload transporting orientation, the first and second sections together with the side walls and the forward wall thereby forming a payload volume in which a payload being transported has a center of mass forward of the pivot points when the body is pivoted upward to dispense the payload; and
a transverse tail panel affixed to the intermediate section, the tail panel being disposed to create an angle of between 0 and 15 degrees from the horizontal when the body is in a payload transporting orientation, thereby enabling the tail panel to act as a partial support for a volume of a low density payload, the tail panel forming a spillway for a payload so that the center of mass of the load remains forward of the pivot points when the body is pivoted upward to dispense the payload.
A truck body includes a front wall, side walls, and a floor. The floor has panels disposed at predetermined angles from the horizontal that, with the other parts of the body, form a payload volume within the body. The floor also includes a tail panel disposed at a lesser angle from the horizontal to facilitate the shedding of the payload when dumping, and further to maintain the center of mass of the payload in a generally forward position during dumping.
- 1. A mining dump truck combination body for the transport of materials of different densities, the body having a front wall, opposed side walls, and a longitudinal floor and the body being mountable to a truck chassis at pivot points under the body, the floor comprising:
a first transverse forward section disposed to create an angle of between 5 and 26 degrees from the horizontal when the body is in a payload transporting orientation; a second transverse intermediate section disposed to create an angle of between 6 and 26 degrees from the horizontal when the body is in a payload transporting orientation, the first and second sections together with the side walls and the forward wall thereby forming a payload volume in which a payload being transported has a center of mass forward of the pivot points when the body is pivoted upward to dispense the payload; and a transverse tail panel affixed to the intermediate section, the tail panel being disposed to create an angle of between 0 and 15 degrees from the horizontal when the body is in a payload transporting orientation, thereby enabling the tail panel to act as a partial support for a volume of a low density payload, the tail panel forming a spillway for a payload so that the center of mass of the load remains forward of the pivot points when the body is pivoted upward to dispense the payload.
- 2. A truck body having a front wall, opposed side walls, and a longitudinal floor, the floor comprising:
a first transverse forward section disposed to create a first predetermined angle from the horizontal when the body is in a payload transporting orientation; a second transverse intermediate section disposed to create a second predetermined angle from the horizontal when the body is in a payload transporting orientation; and a transverse tail panel affixed to the intermediate section, the tail panel being disposed to create a third predetermined angle from the horizontal when the body is in a payload transporting orientation, the tail panel forming a spillway for a payload so that the center of mass of the load remains forward of the pivot points when the body is pivoted upward to dispense the payload.
- View Dependent Claims (3, 4, 5, 6, 7, 8)
- 9. A dump truck body for the transport of materials of different densities, the dump truck body configured to be mounted on a truck chassis having at least one front axle having a center point and at least one back axle having a center point, the center point of the at least one front axle and the center point of the at least one back axle thereby defining a reference line, the dump truck body having a longitudinal floor with a pair of laterally opposed spaced upwardly extending side walls coupled to the floor and a forward upwardly extending front wall coupled thereto between the side walls to create a volume for carrying a payload having a center of mass, the dump truck body further comprising at least one pivot point at which the truck body may be pivotally mountable to the truck chassis, the longitudinal floor comprising:
a first transverse forward section disposed to create an angle of between 5 and 26 degrees as compared to the reference line when the body is in a payload transporting orientation; a second transverse intermediate section disposed to create an angle of between 6 and 26 degrees as compared to the reference line when the body is in a payload transporting orientation; and a transverse tail panel affixed to the intermediate section, the tail panel being disposed to create an angle of between 0 and 15 degrees as compared to the reference line when the body is in a payload transporting orientation, thereby enabling the tail panel to act as a partial support for a volume of a low density payload, the tail panel forming a spillway for a payload so that the center of mass of the load remains forward of the pivot point when the body is pivoted upward to dispense the payload.
- View Dependent Claims (10)
This application a divisional of U.S. patent application Ser. No. 15/173,470 filed Jun. 3, 2016, titled “Truck Body,” now U.S. Pat. No. 10,518,686, which was a divisional of U.S. patent application Ser. No. 13/390,751 filed Feb. 16, 2012 titled “Truck Body,” now U.S. Pat. No. 9,365,148, which was a National Stage Entry of International Application No. PCT/US10/59394 filed Dec. 8, 2010 titled “Truck Body,” which in turn claims priority based on U.S. Provisional Patent Application Ser. No. 61/288,150 filed Dec. 18, 2009 and titled “Flow Control Haul Body,” the entire disclosures of all of which are incorporated herein by this reference.
This invention relates to an improved body for a dump truck, and in particular to a gate-free truck body for use in large-scale mining operations and a style of body that may be adapted for use on numerous types of mining truck chassis, after accounting for weight distribution, wheel base, gross vehicle weight, and other such factors.
In general, the density of coal is about half that of overburden. Thus, a given volume of coal weighs approximately half what the same volume of overburden weighs, and so the volume of a truck body 14 designed to haul coal may be twice as large as a body designed to haul overburden without exceeding the carrying capacity of the truck chassis 12. However, having one set of trucks with bodies for coal and a second set of trucks with bodies for overburden can significantly increase mining costs because of the need to maintain two fleets of vehicles.
To avoid maintaining two sets of trucks, truck bodies 14 designed to perform the task of hauling both coal and overburden have been designed. These bodies are typically called multi-purpose bodies, or “combo” (short for combination) bodies. As a practical matter, because of the different densities of the hauled material, and because of the maximum load weight for which a body may be designed, the combination bodies may haul very different volumes of the different materials.
That is, when hauling low density coal the body may be loaded to a much higher height than is the case when hauling a high density material such as overburden. This difference is shown in
In the last several years, significant efforts to analyze the characterization of payloads and prediction of dumping performance for various floor profiles have provided new insights into designs for combination bodies, and in particular adjustments of the angles of the floor of the combination body. For example, as shown in
Shedding performance can be critical to the performance of a truck body. For overburden placed in a combination body, the payload may occupy approximately half of the body capacity. Thus, when placed in a position for proper axle distribution during road transport, a large portion of the rear of the body is empty. During the dump cycle, however, the material sheds onto the rear section or rear panel of the body, and may form a secondary heap on the rear panel, leading to unacceptable and potentially dangerous conditions especially when dumping over a ridge.
That is, typically, large dump trucks have two front tires 36 on the front axle, and four back tires 38 on the rear axle 39, and so the optimum load-carrying design places approximately ⅔ of the load on the four rear tires and ⅓ of the load on the two front tires. Depending upon the length of the inclined rear panel, the load can form a secondary heap on the back of the body 14 when dumping that then spans between the side walls 18a and 18b. Thus, as the load sheds off the body, the weight distribution (center of mass) of the load may shift aft, resulting in too much of the weight being carried by the back of the truck.
Because the fulcrum of the body being tipped is typically behind the rear tires 38 and axle 39, if at any time during dumping of a load the center of gravity of the load shifts too far to the rear, the front end of truck 10 can be tipped up, meaning that the cab 42 of the truck rises, sometimes several feet. Even if the weight distribution is not so skewed as to cause the cab to rise, if the center of mass of the load shifts too far, the lift cylinders 40 pushing the front of the body 14 up to dump the load may suddenly go from being under compression (pushing the body upward) to being under tension (the body tugging on the lift cylinders), something that can seriously damage the lift cylinders. Thus, improper weight distribution of the load during dumping can suddenly thrust the cab upward, create tension on the lift cylinders, and also cause a sudden dumping of a large portion of the load, which then shifts the center of gravity of the load forward again, thereby causing the elevated cab to drop and forcing the lift cylinders back into compression, further damaging the cylinders and perhaps frightening or even harming the truck driver. Furthermore, moving the pivot point to be in front of the rear tires may cause the body to strike the tires or the ground when dumping, and doing so will also reduce the leverage available to the lift cylinders, increasing the weight those cylinders must lift to dump the load.
As a result, it is important to maintain a proper front to back weight distribution of the load during dumping. Because analysis of the 12/22 body indicated there may be problems with load distribution when dumping from some trucks, a “12+5” or 12/17 dual slope floor combination haul body was designed for those types of trucks with a front portion of the floor angle at 12 degrees from horizontal with an additional 5 degrees incline for the rear portion of the floor resulting in a combined 17 degrees off horizontal. This design provided a relatively large volume or cavity for carrying material without making the body so long as to obstruct dumping as a result of, for example, the end of the body hitting the rear tires or the ground or previously dumped material. However, analysis indicated that, for several reasons the 12/17 body would not work on some chassis.
Because the rear portion of the load or heap is generally conical, for dense material loads there is often several feet between the where the heap strikes the sidewalls 18a and 18b and the rear of the floor 20. In a 12/22 body, the rear floor panel 44 is at an angle 10 degrees greater than the forward floor panel 46 and based on sliding friction will shed payload 10 degrees later than the forward floor. Assuming a 45 degree shed line (that is, assuming the material will shed from the heap when the angle of the surface of the material is at 45 degrees) and an initial heap sloped at 2:1 (that is, the heap will have an initial slope of about 26.5 degrees from the horizontal), individual layers of the heap will begin sliding at the point where the truck body 14 has rotated approximately 18.5 degrees, because (18.5 rotation)+(26.5 heap slope)=45 degrees. At this angle of body rotation, the rear floor panel, which was originally 12+10=22 degrees from the horizontal, will be at an angle of −3.5 degrees from horizontal (22 degrees minus the 18.5 degrees of rotation).
If the static coefficient of friction between the material and the floor is 0.61, the body 14 must rotate an additional 35 degrees for all of the material to shed freely off the rear of the floor 20. The forward floor panel 46 will begin to apply a thrust loading to the accumulating material on the rear panel 44 until the frictional resisting force is overcome, at which time the entire heap will slide as a unit.
A variety of combination bodies have been developed using similar floor designs. To date, many gate-free haul bodies designed to be mounted on chassis made by certain manufacturers are of the dual slope design and generally begin with a floor at an angle ranging from an initial slope of between 7 and 12 degrees from horizontal and then the remaining floor increases in angle near the pivot bore. This extra floor “kick” eliminates the need for a tailgate by increasing the length of the body while still maintaining an adequate volume or cavity for the payload.
Canopy loading is often required to attain the desired payload volume for coal while maintaining acceptable axle (tire) weight-bearing distributions. Even with these duel angle floor designs, the center of mass of the load may shift suddenly aft, resulting in tipping of the cab, or tension on the lift cylinders, or both. The success of these other designs is dependent on numerous factors, including the wheel base of the truck, the maximum load rating of the truck, the length of the body, stress on the body floor due to movement of a large mass of the load to the rear of the body without shedding, shedding of load too quickly or too slowly because of the body design, and other factors. Failure to consider any relevant factors may result in a body that does not properly shed the load.
Further reducing the angle of the floor “kick” (that is, less than the 5 degrees of a 12/17 body) typically results in a body that does not have adequate carrying capacity, as the load may slide off under transport, thus resorting back to a body that requires a tail gate, with the consequent construction and maintenance costs and risks of damage to the tail gate and loading buckets when loading the body. Also, if the floor angle is minimized, near the end of the payload dump cycle significantly more material ends up near the back of the floor. That material can suddenly slide and shed, causing the center of mass/gravity of the load to suddenly shift aft, leading to the risks of the cab suddenly rising (and falling when the material precipitously sheds) and sudden tension (and compression when the material sheds) on the lift cylinders. Therefore, further reductions in the angle of the body floor have typically not been successful.
Because combination bodies present significant possible advantages in haul truck fleet management, design of such a combination body can be greatly complicated by the real world requirements of length, center of load mass, and other such factors. However, a combination body design that might be readily adapted to be employed on different manufacturer'"'"'s chassis would likely present significant advantages. Furthermore, a combination body having a significantly reduced tendency for the center of mass of the load to shift too far to the rear when dumping would likely be highly advantageous. Indeed, many of these advantages would also be quite useful on a high volume body carrying a high density material as well as various other types of bodies.
This invention discloses a truck body floor design that overcomes many of the problems of prior designs. Although there are many alternatives to the specific designs possible, in general the floor may be thought of as including a plurality of panels at different angles relative to the horizontal. For example, the floor may have a front panel at one angle, an intermediate panel at a different angle, and a tail panel at a third angle. Although there is a certain level of design variance for different bodies in different applications, in at least one embodiment the front panel of the floor has an incline typically between 5 and 26 degrees (from the horizontal), and the intermediate panel has an incline typically between 6 and 30 degrees from the horizontal. The exact angles depend on the constraints imposed by the chassis on which the body is to be used as well as the desired load carrying load capacity of the body.
The tail panel is designed to have less of an incline than the intermediate panel, or than the section of the floor immediately forward of the tail panel. Again, the exact incline depends on the chassis and other factors known in the art, but typically the tail panel will have an incline of between about 0 degrees and about 15 degrees from the horizontal. Although there are exceptions, because the tail panel is typically at least level with the horizontal, the tail panel may support a portion of a low-density load, such as coal, providing the body with a greater load volume capacity. When carrying higher density material such as overburden, the tail panel does not typically carry much of the load, and the front and intermediate panels form a significant load-carrying volume.
Therefore, the volume for carrying a low density coal load is not significantly reduced from prior 12/17 and 12/22 and other similar combination bodies. However, when dumping, the load sheds material at a different rate than with prior bodies. In particular, the body is typically pivotally attached to a truck chassis, so that the forward end of the body may be pivoted upward to dump the load over the spillway created by the tail panel.
As a result of the different load shedding and retention characteristics of the present body, the center of mass of the load stays generally forward in the body, typically forward of the pivot point or points connecting the body to the chassis, and a significant secondary heap near the back of the floor does not form and no resulting rotational load torque is transferred when dumping. Thus, the risk of the cab suddenly elevating or of the lift cylinders going into tension is greatly reduced. Furthermore, initial testing and analysis indicates that the load is actually shed at a faster initial rate, and the load may be shed at a faster total rate, meaning that during dumping there will typically be less stress on the lift cylinders at a given angle of rotation than was the case with prior bodies.
Other features and advantages of the present invention will be apparent from reference to the following Detailed Description taken in conjunction with the accompanying Drawings, in which:
As depicted for examples in
The body 14 is pivotally mounted to the chassis 12 by one or more pins 50. In this embodiment, a pair of lift cylinders 40 (one shown in each of
As depicted for example in
As depicted in
As a result of the generally conical shape of the load, and as depicted for example in
As depicted in
As depicted in
Analysis of this floor design indicates that the load will maintain a better weight distribution between the front tires 36 and back tires 38. This appears to be particularly true at increased angles of rotation of the body when dumping. Furthermore, current available analysis indicates that the load will actually shed at an improved rate, and at a lower angle of rotation of the body, than is the case with prior bodies.
When rotating the body depicted in
The overall length of the floor 20 is effectively getting shorter as the body 14 is dumping and the necessary accelerated flow is maintained. The available volume of payload along the heap shear line 76 increases, thereby alleviating significant damming problems (that is, the potential for a portion of the payload to drop unto the rear end of the floor and create a dam or secondary heap that could then resist the flow of payload out of the body). The momentum of the flow above imparts a small amount of apparent lift as a result of these events occurring at the same time. As the body 14 continues to rotate, the shear line moves ahead to the next panel (or level) and the process repeats itself (or, perhaps more accurately, continues).
The analysis described includes comparison of the initial sizes of the loads, the volumes and weights of the loads dispensed from the two bodies at the various angles, and the proportion of the load dispensed at those angles. The approximate locations of the centers of gravity of the respective loads are also set forth in
The analysis of the bodies 14 and their loads depicted in
The data in
The examples set forth in
As may be seen from the chart (
As shown in
Considering other angles noted in the chart (
As further indicated in
At 50 degrees body rotation, the calculated payload remaining in the prior 12/22 body 14 is 114.5 cubic yards and 302,386 pounds. At 50 degrees, the load on the front axle is approximately 91,545 pounds and the load on the rear axle is approximately 546,841 pounds, and approximately 207,636 pounds of the payload has fallen out of the body. At 50 degrees, the front axle load is 14.3 percent, and the rear axle load is 85.7 percent of the remaining load, with 59.3 percent of the load remaining in the body. However, as indicated in
As set forth in
As set forth in
As further indicated in
At 50 degrees body rotation, see line 22, calculated payload remaining in the 12/22/8 body 14 is 86.4 yards and 228,175 pounds. At that point, the load on the front axle is 124,780 pounds (a small increase over 46 degrees) and the load on the rear axle is 439,396 pounds, and approximately 281,741 pounds of payload has fallen out of the body. Notice that between 46 and 50 degrees of rotation, the entire reduction in the load has deducted from the rear axle. This means that at 50 degrees, the front axle load is 22.1 percent, and the rear axle load is 77.9 percent, and only 44.7 percent of the load remains in the body. Furthermore, the load on the lift cylinders at 50 degrees is −46,637 pounds, meaning 46,637 pounds in compression. In contrast with the prior 12/22 body, then, the 12/22/8 body remains significantly in compression even at 50 degrees of rotation.
Furthermore, as shown in
As can be seen, a truck with a 12/22 body has a payload center of gravity that will fall behind the pivot pins at some point after about 48 degrees of rotation, meaning that at that rotation, the truck risks tension on the lift cylinders and rotation of the entire truck about the rear wheels, possibly propelling the cab upward. As can be seen, and as was shown by the calculations discussed, the center of gravity of the payload of the 12/22/8 body does not shift behind the rear wheels even at 54 degrees rotation with just over 25% of the payload remaining in the body.
The mathematical calculations set forth herein were supported by a scale model demonstration. Two model bodies (a dual slope body and one with a three section floor as described) were loaded with different materials and mounted, side-by-side, to a pivot point. The loads were slowly rotated. Both began shedding material at about the same angle of body rotation, though the 12/22/8 model dumped at a higher rate (as predicted by the mathematical model).
At some point in the rotation, roughly determined by analysis of the video to be between about 48 degrees and about 52 degrees, the 12/22 dual slope body actually “jumped” in the rotation and dumped a significant proportion of the load, meaning the load had shifted so far to the rear that the body was no longer being supported by the lifting points, but rather suddenly rotated because the center of mass of the payload shifted behind the fulcrum or pivot pins of the body. Were this to happen in a real world application, the cab of the truck could suddenly be jolted several feet into the air. Furthermore, this sudden rotation could cause the load to suddenly drop and the cab would then drop back to earth. In any event, this demonstrates that the lift cylinders 40 would have almost immediately gone into tension, with the risk of damage to the lift cylinders, and once the load dropped, rapidly back into compression, again with a risk of damage.
Although the embodiments discussed in this disclosure involve a three-part floor, a floor having more sections would also work. Indeed, there is no reason that the body could not have a curved floor rather than the angled flooring depicted, to provide perhaps even more payload capacity. A two part floor would likely also provide many of the advantages of the three part floor embodiment disclosed. Furthermore, although described with respect to a combination body for large mining trucks, the present designs may also be useful for bodies used in other applications. Thus, the present invention has several advantages over the prior art. Although embodiments of the present invention have been described, various modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the invention.