TWO MAIN STYLES
There are two primary types of full-size truck dumpers: Extended Arm and Standard Pivot, also commonly known as Back-On and Drive-Over dumpers, respectively. Each style serves a specific purpose, and in this article, we will explore their features in detail to help you decide which option is best suited for your facility.
Extended Arm (Back-On)
The structural arm extending back to the pivot point gives extended-arm truck dumpers their name. Designers position the pivot point near the mid-point of the hopper, allowing the deck to follow the hopper’s arc. This elevated design raises the dumper higher off the ground, creating ample clearance for the trailer’s contents to fall efficiently into the hopper.
Extended-arm truck dumpers are most commonly used with above-grade receiving hoppers. They can be used without a hopper (see figure 2).
Benefits:
- Typically designed to be entirely above grade, simplifying repairs and maintenance.
- Allows for the use of fixed backstops, reducing maintenance requirements over time (learn more about backstops HERE).
- The most commonly used type of tipper.
When evaluating dumpers, two key factors to consider are driver interface and staging, as well as cycle time. Extended arm dumpers require drivers to back onto the platform rather than drive straight through, which can be slightly more challenging for drivers. Additionally, the cycle time for an extended arm dumper may be slower compared to a standard pivot dumper, primarily due to the time it takes for drivers to position their trucks. Most drivers can position a truck more quickly when driving forward rather than in reverse.
It’s important to note that the overall cycle time is influenced more by the loading and unloading process of trucks and trailers than by the raise/lower time of the dumper itself. With proper site layout and efficient truck staging, an extended arm dumper can approach the time efficiency of a standard pivot dumper. Learn more about cycle time HERE.
Standard Pivot (Drive-Over)
Standard pivot truck dumpers have their pivot point located at the back end of the deck, near the backstop. Due to this pivot placement, standard pivot dumpers remain closer to the ground compared to extended arm dumpers. They typically discharge materials into a hopper or pit located below the dumper. These dumpers are commonly used with below-grade hoppers or for dumping over a wall or into a pit.
Note that standard pivot dumpers qualify as “drive-over” only when accessed from the pivot end. Operators often pair them with pit doors and below-grade hoppers for efficient operation. Designers typically configure dumpers with a pit or wall system as back-on style dumpers.
Backstops:
Back-on style standard pivot dumpers use the same types of backstops as extended arm dumpers, with additional options such as tanker-style and potato gate-style backstops. Drive-over-style dumpers most commonly use tollgate-style backstops. Operators also utilize pop-up and wheel lock backstops, though these are more common on older dumpers or added based on specific customer requests. (See Figure 3 for reference.)
Benefits:
- Enables faster truck cycling, especially with drive-over designs.
- Keeps the truck and deck closer to the ground for added stability.
- Easier for truck drivers to operate, particularly with drive-over configurations.
- Helps reduce traffic congestion in the dumping area.
When considering drive-over style standard pivot dumpers with below-grade hoppers, foundation work and the water table are primary concerns. Below-grade hoppers are similar in construction to above-grade hoppers but often involve more extensive foundation work, making them a costlier upfront option. The below-grade design requires careful attention to groundwater management and maintenance access. However, for facilities handling large volumes of material or accommodating high truck traffic, drive-over dumpers are often the optimal choice. On the other hand, if unloading speed is less critical, extended-arm dumpers with above-grade hoppers may offer a more cost-effective and practical solution.
Summary
This article highlights just a few key considerations when determining the best type of truck dumper to suit your budget and facility needs. Selecting properly sized and well-planned equipment is essential, as it can significantly impact the efficiency and productivity of your operations. At Airoflex, we understand that every facility is unique, and we are here to help you make an informed decision. Feel free to contact us anytime to discuss truck dumper options and explore the best solution tailored to your specific requirements.