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telescoping hydraulic cylinders

Exploring the Different Types of Full-Size Truck Dumpers

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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)

full-size truck dumper with extended arm

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). 

Extended arm on full size truck dumper
full-size truck dumper with extended arm

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)

full-size truck dumper with extended arm

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.

full-size truck dumper with extended arm

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.

full-size truck dumper with extended arm

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.

Are You Storing Your Telescoping Hydraulic Cylinders Correctly?

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Hydraulic Telescoping Cylinders - Airoflex

Proper storage of telescoping hydraulic cylinders is crucial to maintain the longevity of spare cylinders in storage or for cylinders for transport.

General Storage Requirements

What to avoid when storing cylinders

High Temperature/Direct Sunlight: This includes areas near heaters or other equipment that may produce large amounts of heat. Elevated temperatures can damage the cylinders seals, especially when the cylinders are dry. Cylinders should be stored under a roof if possible.

Water: Including rain, snow, wash-down or run-off/drainage area. Low ventilation or damp areas should also be avoided to prevent steel corrosion and rusting.

Sub-Freezing Temperatures: Although cylinders are designed to be operated in sub-freezing conditions, long-term storage in sub-freezing conditions, especially if the cylinders are dry, can cause premature failure of seals.

Dirty Areas: This includes dirt floor building when cylinders are stored in direct contact with soil. It also includes areas with excessive dust/debris build up or high potential for chemical exposure.

Vertical Storage

Cylinders should be stored in the vertical position if possible. Telescoping truck dumper cylinders can be very large and heavy. When stored horizontally the weight of the internal tubes can cause deformation in the seals over time. Vertical storage prevents this by loading the cylinder as it was designed to be in operation. Some seals also required hydraulic pressure to engage. Even with a small amount of oil in the cylinders, vertical storage allows the seals to work properly. although it can be minor, sometimes oil can leak out of cylinders if stored horizontally.

Note: Storing cylinders vertically does not guarantee that no oil will leak from them if they have been filled or contain a trace amount of oil, but it does reduce the likelihood of leaks.

When storing cylinders vertical, the base of the cylinders (the non-telescoping end) should be at the top.

Inverted Cylinders: These would be stored as shown in the picture on the right, in the same position they would be installed.

A-Frame Cylinders: These are stored upside down or in the opposite position in which they would be installed.

Cylinders should be restrained in vertical storage racks to prevent damage to the cylinder, other equipment, or injury to personnel in the event of a cylinder tipping over.

Restraining brands are not required but are a beneficial addition when storing cylinders. Lifting a cylinder by either end would allow it to extend or “scope out”. This can make handling of cylinder a bit more complicated.  restraining bands can be added to prevent the cylinder from scoping out during transport / lifting. Contact
Airoflex if you need restraining bands.

Horizontal Storage

Finished cylinder tubes in a horizontal storage rack.

If cylinders can’t be stored vertically, they can be stored horizontally. A rack similar to what is shown is optimal, but cylinder may be stored on dunnage, if necessary, as long as the below requirements are met.

  • Cylinders should be restrained from rolling.
  • Wood, plastic, or other soft materials should be used to support the cylinders to prevent damage to the main stage from metal-on-metal contact.
  • Do NOT support cylinders from the pin eye of the base pin. See diagrams below for proper support locations.

Note: Telescoping hydraulic cylinders stored horizontally are more prone to leaking if they contain any oil. There is also a chance for deformation of the seals if left in one position for extended periods of time. Cylinders should be rotated every three months in storage to prevent deformation of the packing. If cylinders are stored in direct sunlight, high temperatures areas, or areas with large temperature changes, the cylinder may extend (scope-out) on its own. This is typical only a few inches but may be up to multiple feet. This is due to thermal expansion of the oil and/or the tubes. If does not damage the cylinders, and any extension can be collapsed by pushing on the top of the pin eye (do not use large equipment to collapse the cylinders as it may damage them).