Why the Compressor Frame is a Major Component to Maintain - Samco

Compressors are versatile machines as they are used extensively in numerous industries. The equipment plays a crucial role in petrochemical, gas, and chemical industrial processes and comprises several components. Each component has a significant role in delivering the final result in an industrial process.

Some reciprocating compressors components contribute in numerous ways, such as:

  • Boosting the durability of the machine
  • Assisting with rotation during the process
  • Heat management
  • Narrowing or channeling gas flow, etc.

However, one of the significant components of a compressor that has drawn little attention is the compressor frame. Here’s what you need to know about this vital compressor component and why maintaining it is crucial to the overall deliverability of the machine.

The Compressor Frame

The first thing that catches one’s attention when you look at a compressor is its rugged and heavy frame, otherwise known as the crankcase. The compressor frame encloses every rotating component that makes up a complete machine, such as the crosshead guide, cylinder, etc. The frame is a rugged, heavy casting with the cylinders and crossheads actually mounted on it.

The crankcase or frame has a rectangle or square shape, depending on the type of compressor you’re using. The compressor frame’s primary role is to support the crankshaft.

The compressor manufacturer rates every frame that comes with a particular machine for rod load, speed (revolutions per minute or rpm), and continuous horsepower. The rated horsepower of compressors is primarily determined by the peak horsepower that can be transmitted via the crankshaft to the cylinders within the compressor. The rod load refers to the force imposed on the piston rod by the pressure differential between the 2 ends.

Every compressor frame is designed for a specified maximum number of cylinders. The crankcase itself doesn’t indicate the primary duty of the machine or the number of stages. Individual frames can be used for numerous sizes of compressor cylinders as well as a wide variety of applications.

Compressor frames are typically classified as integral-type or balanced-opposed (separable).

Integral-type compressor frames are identified by having power cylinders as well as compressor cylinders mounted on the same frame and powered by the same crankshaft.

On the other hand, balanced-opposed (separable) compressor frames are distinguished by the adjacent pair of crank throws at 180 degrees out of phase. The frame is separate from the driver.

Crankcase Body Parts

The crankcase supports the crank mechanism consisting of a double crank and 6 connecting rods. The bottom of the frame serves as an oil pan. Another specific oil storage tank – a continuation of the oil pan – sucks up the lubricating oil expected by the crank mechanism from here.

The side of the compressor frame installs an oil distributor while the oil filter pipe is installed at the upper part of the crankcase. The oil from this oil distributor flows right through the oil filter.

The crankcase has large cover plates on its 2 front sides, which help ensure the frame with the crank mechanism never leaks oil. The frame also has a ventilation device that efficiently balances the pressure within and outside. The cylinder within the crankcase is installed in 2 unique rows. Each row has 3 W-shaped cylinders, with a 60-degree angle between the 2 rows of cylinders.

The crankshaft within the crankcase is usually forged from specially-treated heat-treatable steel. Two long-life roller bearings support the crankshaft. One side of the driving end is a cylindrical roller bearing, while the other end is a spherical roller bearing.

The crank arm has a fixed balance iron compensating for the inertia force. Three running connecting rods are on the hardened crank pin of both crankshafts. Lubricating oil is pressed right into the connecting rod bearing via the oil circuit within the crank.

The six connecting rods come with oil passages to small end bearings. Pressure lubricates the big end bearing system of the connecting rod. This is an alloy split bearing made up of 3 components. The small end bearing bush is also lubricated by pressure and serves as a bearing for the crosshead pin.

Why Maintenance is Key for the Compressor Frame

Maintaining the compressor frame is highly crucial for the peak performance of the equipment. As you already know, the crankcase – which has bushings, bearings, crosshead guides, timing gears, etc. – comes with an oil circulation system that efficiently lubricates the entire crankcase area.

One significant way to maintain the compressor frame is by using the compressor manufacturer’s recommended lubricating oil. Oil drain intervals should span from 4,000 to 8,000 hours of operation. Using periodic oil analysis to monitor lubricating oil and equipment conditions is also essential.

The most crucial aspect of compressor frame maintenance is reading the user manual. Most issues associated with the crankcase can easily be solved by going through the user manual. Unfortunately, many compressor owners somehow forget about user manuals and instead make distress calls for issues that can be remedied easily.

Never try to fix or tinker with anything on the compressor without first consulting the user manual. Ignoring this vital step may cost you a lot of money down the road. In addition, making improper adjustments to recently purchased compressors can render the warranty invalid or null and void.

Therefore, always consult the manual anytime there’s a glitch. However, you may find that some issues can easily be fixed and don’t require the attention and services of certified technicians.

Lastly, consult a certified technician if you want the intervention of pros during maintenance. The pros would know the steps to take when it comes to compressor frame maintenance and do everything to ensure your machine is in excellent operating condition for peak performance.


Compressors function excellently in a wide range of industries due to the components they are made of. Each component works conjointly in order to give the machine an incredibly high or peak/maximum performance.

Bear in mind that although different manufacturers make compressors, they essentially showcase similar components. The compressor frame is one of the significant components that primarily supports the machine’s day-to-day operations, irrespective of the industries it functions in.

From industry standards like Ariel compressor parts to Ingersoll Rand and Worthington compressor parts, we carry compressor parts you can trust and the service you can count on.