Table of Contents
1Literature on Pneumatic (Air-powered) Drive Systems and Hydraulic Drive Systems
1Pneumatic drive system
1Hybrid drive systems
2Comparison between these Two Systems with the Conventional Power Train
2Pneumatic drive systems
2Hybrid drive systems
3Critical Analysis of the Two Alternative Power Systems
Literature on Pneumatic (Air-powered) Drive Systems and Hydraulic Drive Systems
Pneumatic drive system
Pneumatic drive systems, mostly known as pneumatics, rely on compressed gasses for operation. The key parts of a pneumatic drive system include an electric pump/air compressor, a reservoir tank, pneumatic actuator, and control valves. Although pneumatic drive systems found wide industrial application in the beginning of the industrial era, their history dates back to the first century when wind powered systems were thought about. The vacuum was invented in mid 1600s, which is a basic pneumatic system (Alavudeen & Venkateshwaran, 2010). Since then, pneumatic drive systems have received wider attention and further improvements for industrial application especially in automated control of components such as doors.
These alterative drive systems are highly applicable in industrial plants especially because of the presence of compressed air available in the assembly system. In addition, pneumatic systems offer a number of benefits compared to others drive systems. Firstly, they are economical especially those running on compressed air because of the readily availability of this resource. Further, air is an economical source of energy and these two benefits make pneumatic systems to be less costly and easier than conventional ones (Patrick & Fardo, 2009). In addition, pneumatic power systems operate at high speeds because they are highly responsive. Operation and maintenance of these systems is easy making them very economical. Moreover, since air is not explosive, pneumatic systems are can be used in explosive atmospheres with no risk of explosion (Patrick & Fardo, 2009). However, air or gases are highly compressible, which means that there is load limitation for this system. Indeed, pneumatic drive systems are used in light load applications such as small robotics. Secondly, owing to high compressibility of air, precise control and positioning is difficult to control. Further, challenges are experienced providing dry and clean air supply. Further, they are noisy owing to vibration of motors and air cylinders (Alavudeen & Venkateshwaran, 2010). Therefore, they cannot be used in areas where quietness is a crucial requirement.
Hybrid drive systems
As the name suggests, a hybrid drive system combines two or more technologies of drive systems for improved efficiency, speed, load application, cost effectiveness, and applicability. Efforts to improve industrial processes have resulted to the introduction of and further improvements in hybrid drive systems. A typical example of hybrid drive system is one used in motor vehicles, which combines the conventional system and an electric one comprising of a battery and gearing systems (Duffy & Wright, 2016). The advantage with this alternative drive system is that it combines strengths of each of the system used to produce a highly effective, efficient, robust, and economical drive system. Moreover, it minimizes weaknesses of each of the systems forming the hybrid power source. For example, one combining conventional and electric system will minimize pollution coming from IC engine, reduce noise, cut fuel costs thereby improving economy, and improve on versatility. However, these alternative drive systems are usually expensive in terms of initial and running costs.
Comparison between these Two Systems with the Conventional Power Train
Pneumatic drive systems
A conventional power train system comprising of an internal combustion engine, meshing gear drive train, driveline, and final drives is an alternative drive system to pneumatic and hybrid drive systems. It offers a number of advantages and disadvantages over these two alternative drive systems. In comparing the conventional drive system with pneumatic drive system, the former is cleaner than the former. IC engine emits carbon dioxide, smoke, and other air pollutants as part of byproducts of the combustion process. Consequently, it means that the conventional power system may not be applicable in areas where air quality is of concern such as in food packing and packaging rooms. However, since pneumatic drive systems do not emit such air polluting substances, they are easily and widely applicable.
Another disadvantage of conventional drive systems over their pneumatic counterparts is on size. Conventional drive systems are often larger compared to pneumatic systems because the former have more elements than the latter. In addition, pneumatic drive systems are faster than conventional drive systems. Moreover, conventional systems are noisy compared to pneumatic ones mainly because of the noise that IC engines, gears and other components generate during operation.
However, conventional drive systems offer better accuracy in positioning than pneumatic systems because the former do not use fluids, which are compressible. In addition, load limit is higher in the case of conventional systems than in pneumatic drive systems.
Hybrid drive systems
As earlier mentioned, hybrid drive systems are designed to make use of strengths of each of the member system. One benefit of hybrid systems is that they carry more loads at reduced cost compared to conventional systems. For instance, while a conventional system will solely rely on diesel as the energy source, a hybrid system will bring in new energy sources such as hydraulics, pneumatics, and electricity. In so doing, they minimize excessive use of hydrocarbons, which in turn cuts drawbacks of its use including carbon emission, noise generated by the IC engine, and limited areas of application. However, hybrid systems are expensive to install and operate. Moreover, maintenance is quite complicated compared to conventional system. For instance, if it combines pneumatic and conventional drive system, maintenance implies combination of skills for repairing and maintaining the two subsets, which could be expensive.
Critical Analysis of the Two Alternative Power Systems
The high speed of operation, ease of use and maintenance, low cost, and versatility of pneumatic drive systems outweigh its limitations especially on noise generation, accuracy, and load limitation for the pneumatic drive system. Therefore, it is worth improving this drive system to make it more useful. One area of improvement is on load limitation whereby multiple actuators can be used to support a single load. When each of the actuators is provided with a set of one-way valves to prevent compressed air getting back to the cylinder once load is applied, it is possible to increase load.
Hybrid systems are becoming more common in industrial application with efforts to improve on various aspects such as cost and efficiency. Although they could be more expensive especially in installation, their benefits especially in terms of reducing hydrocarbons use in IC engines outweigh costs and disadvantages. Running costs are a major concern especially now that hybrid systems are still in development. A notable area of improvement is on coming up with appropriate system mix to achieve optimal benefits.
Pneumatic drive systems are highly versatile although they have load limitations
Hybrid drive systems combine benefits of each system used while eliminating limitations of each of the systems in the effort to improve economy, speed, efficiency, and accuracy
Although pneumatic systems found industrial application in the industrial era, the concept was developed several centuries ago
Alavudeen, A. & Venkateshwaran, N. (2010). Computer integrated manufacturing. New Delhi, India: PHI Learning Private Limited.
Duffy, O. C. & Wright, G. (2016). Fundamentals of medium/heavy duty commercial vehicle systems. Burlington, MA: Jones & Bartlett Learning.
Patrick, D. R. & Fardo, S. W. (2009). Industrial process control systems. Liburn, GA: Fairmont Press, Inc.