What Is An Underbody Air Compressor?

January 27, 2020

DTM70-RAM-Install-Render2An underbody air compressor is any air compressor that has been designed to mount under the body of a service vehicle. These air compressors are small but mighty, and are widely appreciated by upfitters and operators because they’re out of sight, save space, and reduce weight.

“Underbody air compressor” is a colloquial, less common term that isn’t widely used within the industry. Rather, these systems are more frequently called underdeck air compressors, PTO air compressors, or vehicle-mounted air compressors.

All underbody air compressors use rotary screw technology, as rotary screw air compressors are smaller and more efficient than reciprocating air compressors. Only a few manufacturers throughout the world design underbody air compressors, with VMAC serving as a leader in this innovative space.

Although technically not “under the body”, a popular alternative is the UNDERHOOD® air compressor, which is mounted directly to a vehicle’s engine and provides similar benefits.

Types of Underbody Air Compressors

Underbody air compressors use one of two existing power sources on a vehicle:

  • PTO Port
  • Hydraulic Port

In theory, it’s relatively straight-forward to mount an air compressor to an existing PTO or hydraulic port. In practice, however, it becomes a bit more challenging. There is a very limited amount of space under a vehicle for additional components and manufacturers require ingenuity to overcome this challenge.

In addition to the two power sources, there are two common types of underbody air compressors:

  • Shaft
  • Direct-Mounted

Shaft: The most basic way to fit all the components under a vehicle is using a shaft. A shaft allows a manufacturer to place the components wherever they can easily fit and then connect it to the air compressors with a shaft. Unfortunately, shafts can cause alignment issues, are more likely to break, have unnecessary moving parts, require modifications to the truck’s transfer case, and add both parts and installation labor costs.

Direct-Mounted: The more professional type of underbody air compressor is designed to place the air compressor components directly on or beside the power source. This requires proper engineering and manufacturing capabilities, as components must be smaller and more intentionally designed, but results in systems that are compact, powerful, and durable. All of VMAC’s underbody air compressor designs utilize this style.

VMAC’s Direct-Transmission Mounted air compressor mounted to the PTO port of a RAM truck

Hydraulic Options For Underbody Air Compressors

Many underbody air compressors come with a hydraulic option, which allows operators to add hydraulic power to their vehicles. Underbody air compressors with hydraulics are popular with crane operators, as they easily allow operators to run hydraulic systems and air compressor systems simultaneously.

For example, VMAC’s DTM70-H system allows customers to operate small to medium sized air tools, as well as a hydraulic crane or other equipment simultaneously. Check out this video to see it in action:



Additional Underbody Air Compressor Resources

To learn more about underbody air compressors, explore the following resources: