There are several transmission methods for the drive system of air compressors

Belt drives have low efficiency. :lol:lol:lol:lol:lol:lol:lol:lol

In the drive systems of air compressors, there are generally two types: direct drive and belt drive. For a long time, the question of which of these two drive methods is superior has been one of the main topics of debate in the industry. Direct drive in screw air compressors refers to the motor shaft driving the rotor through a coupling and gearbox for speed adjustment; this is not actually a true direct drive. True direct drive refers to the motor being directly connected (coaxially) to the rotor, with both having the same speed. This situation is obviously extremely rare. Therefore, the view that direct transmission involves no energy loss is incorrect. 　　Another type of transmission is belt drive, which allows the speed of the rotor to be changed by using pulleys of different diameters. The belt drive systems discussed below refer to state-of-the-art automated systems that meet the following conditions: the belt tension in each operating condition is at an optimal level. 　　By avoiding excessive starting tension, **the service life of the belt is extended, while the load on the motor and rotor bearings is reduced. 　　Always ensure the correct pulley connection. 　　Replacing the belt is quite easy and quick, without the need to adjust any existing settings. 　　The entire belt drive system operates safely and without faults. 　　It is worth noting that some of the products manufactured by those manufacturers who advocate direct gear transmission also use belt drives. 　　Comparison between gear transmission and belt transmission: 1. Efficiency Excellent gear transmissions can achieve efficiencies of 98%-99%, while well-designed belt transmissions can also reach 99% efficiency under normal operating conditions (see the research report published by Professor Heinz Peeken in ‘Transmission Technology’ in December 1991). The difference between the two does not depend on the choice of transmission method, but rather on the manufacturer’s design and manufacturing capabilities. 　　2. No-load energy consumption: In the case of direct gear drive, the no-load pressure generally needs to be maintained at above 2.5 bar, with some systems even reaching 4 bar, in order to ensure proper lubrication of the gearbox. 　　In the case of belt drive, theoretically the no-load pressure can be zero, as the oil drawn in by the rotor is sufficient to lubricate the rotor and bearings. Generally, for safety reasons, the pressure is maintained at around 0.5 bar. 　　Taking a 160kw gear-driven air compressor as an example, operating 8000 hours per year with 15% of that time (i.e., 1200 hours) spent idling, this machine will consume 28,800 kwh more in electricity costs per year compared to a compressor of the same power but with a belt drive system (assuming an idle pressure difference of 2 bar between the two machines, resulting in a roughly 15% difference in energy consumption). Over the long term, this represents a significant expense. 　　3. Oil loss Experienced practical users know that in the event of oil loss, the gearbox is the first to suffer damage. Belt drive systems do not have such safety issues at all. 　　4. Design the working pressure according to user requirements. Usually, the working pressure required by users does not exactly match that of the manufacturer’s standard models. For example, if the user requires a pressure of 10 bar, depending on the condition of the post-treatment equipment, as well as the length of the piping and the level of sealing, the operating pressure required of the air compressor may be 11 or 11.5 bar. In this case, an air compressor with a rated pressure of 13 bar is generally installed, and the outlet pressure is set to the required operating pressure on-site. At this point, the displacement remains essentially unchanged, as although the final operating pressure decreases, the speed of the rotor does not increase. 　　Manufacturers of belt drive designs that represent modern technology can simply change the diameter of the pulleys, thereby enabling the working pressure to be set to exactly meet the user’s requirements; as a result, users can obtain a higher air volume using motors with the same power. For gear drives, it’s not that convenient. 　　5. Change in pressure of the installed air compressor Sometimes, due to changes in the user’s production process conditions, the design pressure of the air compressor purchased initially may be too high or too low, and it may be desired to make such a change. However, for air compressors with gear drives, this task is very difficult and costly, while for those with belt drives, it is a simple matter – merely replacing the pulley is sufficient. 　　6. Installing new bearings When the rotor bearings need to be replaced, in air compressors with gear drives, the gearbox as well as the main shaft bearings of the gearbox must be overhauled simultaneously, and the costs involved are unaffordable for users. For belt-driven air compressors, such a problem simply does not exist. 　　7. Replacing the shaft seal 　　All screw-type air compressors use an annular shaft seal, which needs to be replaced after reaching a certain service life. For gear-driven air compressors, it is necessary to first separate the motor and the coupling in order to access the shaft seal, which makes this task time-consuming and labor-intensive, thereby increasing maintenance costs. For belt-driven air compressors, it is much easier to simply remove the pulley first. 　　8. Damaged motor or rotor bearings In gear-driven air compressors, when the motor or rotor bearings are damaged, it often affects the connected components, causing both direct and indirect damage. This situation does not exist for belt-driven air compressors