Why does my compressor system perform differently at higher altitudes?

Anyone who has had to use a compressor at a high altitude knows how frustrating it can be. Compressor performance is degraded and it can take a lot longer to complete tasks. People who move to or work in areas that are at a higher altitude are often surprised when their compressor seems to be working slower than normal.

How an Air Compressor System Works

Mobile air compressor systems commonly in use typically consist of a gas or diesel engine powering an air compressor. When you turn on an air compressor system, it draws in ambient air through the compressor intake and compresses it to a smaller volume. This compressed air can then be stored in a storage tank or used to directly power your tools and equipment. Once the air storage is full or the tools being used are no longer running, the compressor stops drawing in and compressing air by either shutting off the engine and compressor or entering some sort of a standby mode.
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Power requirements for your industrial engine powered air compressor

So you’ve decided you are in the market for an air compressor to add to your existing industrial engine or to include as part of a new piece of equipment you are designing. Maybe you or your customers are tired of having to haul another separate piece of equipment around to job sites. Maybe you’re looking to open up new markets with a product that does it all. In any case, you are going to have to figure out what your needs are so you can start looking for the right piece of equipment. Continue reading “Power requirements for your industrial engine powered air compressor”

Methods to Power Your Air Compressor with an Industrial Engine

Powering your air compressor by an industrial engine can be done by various means.  Choosing the way you power your compressor should be decided by a number of factors.  Space, existing components and systems, weight and your engine options are all variables to consider.   In this article we talk about the most common found in the market today.

Engine Mounted FEAD Belt Drive

Auxiliary components are commonly mounted directly to the engine and driven from a serpentine or V belt. This is termed “Front End Accessory Drive” (FEAD) and is often used to drive alternators, generators, air conditioning compressors, water pumps, cooling fans etc.  Air compressors can also be driven via FEAD belt off the front of an engine.  This can be in line with the existing belt system or by adding another pulley to the crankshaft and designing another belt system. The driven and driving pulley diameters can be customized to provide the required compressor output at a given engine speed. Belt drives will also provide some damping of potentially damaging torque pulses.  The compressor can be driven via a clutch or fixed pulley depending on whether it is desirable to be able to completely stop the compressor while the engine is running. A custom bracket will likely be needed to mount to the engine to support the compressor and if equipped, the secondary belt system components such as the idler(s) and tensioner.

Frame Mounted Belt Drive

To simplify the design of a bracket to mount the compressor it can be mounted to the base frame instead of directly to the engine.  The belt is still driven off a pulley mounted to the engine’s crankshaft.  Generally, a V belt will be used instead of a serpentine belt as it is better able to handle misalignment and variations in tension due to the changes in positioning between the engine and compressor under operating conditions, especially if the engine is not hard mounted to the frame.

Auxiliary Port Direct Drive

Many industrial diesel engines and some gasoline engines come equipped with an auxiliary PTO port used to power bolt-on accessories.  These ports are usually part of the front or rear engine cover and are driven via the crankshaft/camshaft/fuel pump gear-train.  Auxiliary ports come in various configurations usually conforming to an industry standard.  The connection to the drivetrain is generally either a splined port or direct gear mount.  Over or under drive ratios may also be available via bolt-on adaptors.  Although traditionally small reciprocating compressors are driven by these auxiliary ports there is a growing number of higher volume rotary screw compressor designs taking advantage of this PTO drive method.

Flywheel Direct Drive

A common method of power to an air compressor is to drive it through a coupling directly off of the flywheel.  Commonly used industrial couplings are designed to dampen vibration and torque spikes while often allowing some misalignment between the engine and compressor.  To generate the high RPM required for rotary screw compressor operation a speed increasing gearbox is commonly used.

Flywheel Belt Drive

Much the same as the FEAD drive listed above, a pulley and belt configuration can be connected to the flywheel to power your compressor.  The main advantage to using a belt driven from the flywheel is that there are generally fewer components to work around which typically makes designing the bracket and belt system simpler.

Hydraulic Drive

While not directly mounted to the engine, the use of an engine-driven hydraulic motor to power an air compressor is not uncommon.  If the engine or equipment is using hydraulic power for other functions, adding hydraulic power to run a compressor can be a convenient option. This method is less efficient compared to the direct drive methods discussed above. It may require additional hydraulic cooling capacity and will burn more fuel for a given compressor output. This method does allow more positional flexibility between the engine and compressor which can be helpful if there is limited space on or around the engine.

Electric Drive

Like the hydraulic drive above, using electric power generated by the engine is another way of producing air power.  While the availability of sufficient power to produce large air volumes is unlikely, small electric driven compressors can be used when air flow and duty cycle are very low.


Ultimately choosing a drive method for your compressor comes down to your unique situation, air compressor requirements, and equipment available to you. The choice of how best to drive your air compressor system is best discussed with the members of the application team of your engine distributor and compressor manufacturer.

If you have any questions about this article or anything mobile compressor related, please contact us.

The Top 7 Questions When Adding a Compressor to Your Industrial Engine

When you are looking at considering putting a compressor on a John Deere™, Kubota™, Cummins™, Caterpillar™, Deutz™, Robins-Subaru™, Isuzu™ or a multitude of other industrial engine manufacturers, there are some key questions about your engine and your application that need to be answered before you can determine the best solution.

Here are some important questions to have answered:

1. What are you using the air for?

This helps to ensure that you are choosing the most appropriate solution for your unique requirements. How many CFM (cubic feet per minute) and at what pressure do you require to run your tools or equipment correctly?

2. What duty-cycle do you require for the compressor to operate?

This refers to how much you are using the compressor in a given time frame. Do you need air continuously for a piece of machinery (100% duty cycle) or infrequently to do small jobs? (say 15 minutes at various intervals over an hour – 25% duty cycle). This is critical information for selecting the type of air compressor solution you should be pursuing. Is it a heavy duty application where a robust solution like a rotary screw air compressor would be best, or is it a light duty application that an inexpensive reciprocating air compressor is going to provide better value? How critical is the air requirement? How much will downtime cost you?

3. What is your engine load?

Do you require air while running another piece of equipment from the same engine? If multiple pieces of equipment are running at the same time, the power being drawn from the engine is greater than if you turn off each component when not being used. How much horsepower are you already using for your equipment and how much will be available to power the compressor? Not only does this information help calculate the power requirements but also acts as a guide to the type and complexity of control system needed. It is important to ask, “what is really required?” instead of, “what would be nice to have?”.

4. What air pressure do you require?

This also helps to determine the power requirements for the compressor. It potentially determines what type of compressor will be required. High pressure applications require specialized compressors. It is important to not over specify your needs as that may increase costs, create less reliable systems and potentially shorten tool and equipment life downstream of the compressor.


5. What environment do you operate in?

This information is really important for you to know in order to correctly specify cooling and filtration requirements. If you work in frigid conditions, you will also need to consider ways of ensuring the compressor will work well in the cold. Extreme heat requires more cooling. Do you work in dusty environments? If so, protecting your compressor from dirt and other debris will improve the longevity of your compressor. Understanding how the engine and equipment behaves while operating is also a requirement. Is it stationary, moving or rocking back and forth?

6. What is your engine and equipment mounted to?

Are you mounting your equipment to a stationary skid or trailer? Is it truck mounted or on an auxiliary piece of equipment attached to the truck? Are you limited by the space around the unit or is there a requirement for the equipment to be within the confines of an enclosure? Oftentimes, compressors must be mounted to an existing piece of equipment that already has a frame and a sheet metal enclosure, without making changes to the existing structure. Vibration also has to be addressed if your equipment operates in a high vibration environment.

7. What engine are you using?

Can you make changes to your engine if needed?There are many options available from the engine manufacturer for each engine and some are extremely important to the mounting of an air compressor. Engine mounts, coolers, water pump options, auxiliary ports, alternator size, front cover, harmonic balancer and pulley are a few things to consider. What is the horsepower of the engine? Is an auxiliary port available, if so, what type is it? How much free space is around the engine? How about the radiator; is there extra cooling capacity available to handle the heat load from the compressor or will you need to either increase its size or add additional cooling capacity?

Along with the engine details, you need to know what speed your engine is running at. What is the typical operating RPM (revolutions per minute)? The minimum and maximum RPM information is also important. If you want a belt driven, clutch actuated compressor solution, you will need to know at what engine RPM the clutch will be engaged. If the speeds are too high, there is a risk of the clutch burning out prematurely; a control system would be required to prevent this from occurring. Compressor safety systems can also be programmed in to prevent occurrences like over temperature conditions.


There is nobody that knows your business, environment and equipment better than you. With your knowledge and answers to these questions, you are well on the way to adding a compressor to your piece of equipment.

Lastly, it is important to find an air compressor provider that will work with you, and provide the support and expertise that you need. A compressor can be purchased from anyone, but are they asking these questions up front, or just trying to sell you a compressor and leaving you high and dry when it doesn’t meet your expectations, or leaves your operator with an expensive breakdown in the field? Do your research to ensure you get the results you require.

If you need help answering these questions, please don’t hesitate to contact us.