Applications of hydraulic systems
Objectives
After reading this chapter the student will be able to:
• Understand the arrangement of various components in a hydraulic system
• Understand the subject of hydraulics as applied to the following:
– Hydraulic-powered and controlled sky tram
– Bendix hydro boost brake system
– Power steering
– Welding
– Bridge maintenance.
Introduction
There are essentially three ways of transmitting power:
1. Electrical
2. Mechanical
3. Fluid power.
Most applications actually use a combination of all these three means, to obtain an efficient overall system. In order to exactly determine which of the above methods is best suited to a particular application, it is important to know the salient features of each method. For example, hydraulic systems can transmit power more economically than mechanical systems, over a larger distance. As in the case with mechanical systems, hydraulic systems are not hindered by the geometry of components in the system.
Industry today is becoming increasingly dependent on automation, in order to increase productivity. Hydraulic or fluid power can be considered to be the ‘muscle’ of automation and is therefore being widely used in various applications. In the discussion to follow, we shall discuss the relative advantages of hydraulic systems and their various applications.
Advantages of hydraulic systems
A hydraulic system has four major advantages, which makes it quite efficient in transmitting power.
1. Ease and accuracy of control: By the use of simple levers and push buttons, the operator of a hydraulic system can easily start, stop, speed up and slow down.
2. Multiplication of force: A fluid power system (without using cumbersome gears, pulleys and levers) can multiply forces simply and efficiently from a fraction of a pound, to several hundred tons of output.
3. Constant force and torque: Only fluid power systems are capable of providing a constant torque or force regardless of speed changes.
4. Simple, safe and economical: In general, hydraulic systems use fewer moving parts in comparison with mechanical and electrical systems. Thus they become simpler and easier to maintain.
In spite of possessing all these highly desirable features, hydraulic systems also have certain drawbacks, some of which are:
• Handling of hydraulic oils which can be quite messy. It is also very difficult to completely eliminate leakage in a hydraulic system.
• Hydraulic lines can burst causing serious human injuries.
• Most hydraulic fluids have a tendency to catch fire in the event of leakage, especially in hot regions.
It therefore becomes important for each application to be studied thoroughly, before selecting a hydraulic system for it. Let us now discuss some of the most important and common hydraulic system applications.