Tilt angle is a key factor in ensuring the safe and efficient operation of a truck dumper. It affects how smoothly and effectively a load is discharged, as well as the overall stability of the equipment during use. In this article, we’ll explore what tilt angle is, how to determine the correct angle for different applications, and the potential risks and safety hazards associated with using an improper tilt angle.
Terms
Tilt Angle: The angle of the dumper deck with respect to horizontal. See Figure 1.
Angle of Repose: The steepest angle at which a sloping surface formed of a particular loose material is stamble. See Figure 2.
Ѳ (theta): Symbol typically used to represent angle.
Figure 1: Tilt Angle
Figure 2: Angle of Repose
How Much Tilt Angle Do I Need?
As a general rule, the optimal tilt angle for a truck dumper is the minimum angle at which the material will flow freely out of the trailer. For most bulk materials, this typically falls between 30 and 60 degrees. However, certain environmental and material factors can reduce flowability and may require the angle to be increased. These factors include:
- Freezing Weather, Ice/Snow
- Wet/High Moisture Content Material
- Sticky or Adhesive Materials
Many facilities receive a wide variety of materials under different conditions. In these cases, it’s often recommended to set the dumper based on the material with the highest angle of repose to ensure consistent unloading performance.
Additionally, some trailer types—such as tankers—may require much lower angles, generally in the range of 15 to 30 degrees, due to their design and how material is contained.
Setting the Tilt Angle
While some dumpers may have multiple limit switches, the one that controls tilt angle is almost always located at the main pivot point. There are two common types of limit switch mounting configurations used to adjust the tilt angle:
- Limit Switch Adjustment. See Figure 3.
- Tab Adjustment. See Figure 4.
In the Limit Switch Adjustment style, the trigger tab is fixed in place, and the tilt angle is adjusted by moving the limit switch forward or backward along its mount. For finer tuning, the limit switch arm can also be adjusted.
In contrast, the Tab Adjustment style features a fixed limit switch position (though the arm can still be fine-tuned), while the trigger tab is field-welded in place to achieve the desired tilt angle.
Both styles are commonly used, but newer dumpers tend to favor the Limit Switch Adjustment method due to its ease of adjustment and the fact that it does not require field welding.
Figure 3: Limit Switch Adjustment
Figure 4: Tab Adjustment
Hazards
Improper use of the tilt angle can cause serious problems with the equipment and pose safety concerns.
- Never Exceed a 63 Degree Angle: 63 degrees is a common angle used throughout the industry. This angle will allow most materials to flow freely while keeping the center of gravity of the truck and/or trailer in front of the dumper pivot. If a higher angle is required, a specialty solution/equipment may be required.
- Cylinder Damage: Most telescoping cylinders used on truck dumpers are designed with some extra stroke at the top and bottom range of motion. Do not set the tilt angle based on fully extending a cylinder. The cylinder may fully stroke out at an angle greater than 63 degrees. This can also put extra impact stress on the cylinder.
- Center of Gravity: Tilting a dumper more than 63 degrees can start to affect the balance point of the truck/trailer that is being dumped. If the angle is too steep, the trailer may start to fall back off the dump deck. The dumper and trailer are also most susceptible to winds at higher angles as there is less weight on the tires and landing gear (and tractor).
Conclusion
Understanding the angle of repose of your material is key to setting your truck dumper at the ideal tilt angle for efficient and safe operation. It not only boosts performance but also plays a critical role in maintaining safety standards. If you’re unsure about the angle of repose for a specific material, need help determining the right angle, or are dealing with sticky or non-flowing material, the Airoflex team is here to help. Don’t hesitate to reach out with any questions or concerns.