Monday, 9 March 2015

BASIC PRINCIPLES OF HYDRAULIC SYSTEM

BASIC PRINCIPLES OF HYDRAULIC SYSTEM

We have discussed in previous post about causes of hydraulic system overheating and we have also analyzed the cost of hydraulic oil leaks as well as various reasons of hydraulic hose failure.

Today we will discuss how to start to find the root cause of a problem in a hydraulic system.

Hydraulic system might be simple or complex but we will have to start with the basic concepts of hydraulic system to find the root cause of a problem and its real solution.

So what are the basic concepts that we have to keep in mind during the analysis of a hydraulic problem?

Let us understand ....

Basic concepts of hydraulics

The basic concepts that we have to keep in mind during the analysis of a hydraulic problem are mentioned here .
  1. Hydraulic pump always produces flow, it will never create pressure.
  2. Pressure would be produced due to resistance in fluid flow, if there is no resistance in fluid flow there will not be any pressure or pressure will be zero.
  3. Speed of actuator depends on fluid flow and actuator speed will be directional proportional to the fluid flow.
  4. Fluid will always find the path of lower resistance.
  5. Actuator force depends on the fluid pressure.
  6. Pressure drop in hydraulic system will always produce the heat.
So, we have discussed the basic concepts of hydraulic system that we will apply during searching the root cause of a hydraulic problem. 

Let us consider that if we have one hydraulic problem where hydraulic pump is not delivering the required pressure.

So how we will approach by keeping above concepts in mind?

We will start from the pump, we will try to find that weather pump is creating flow or not. If pump is not producing flow, we must have to check following points.
  • Desired oil level in tank
  • Inlet valve, weather it is open or closed
  • Suction filter or strainer
  • Air breather, weather it is healthy or clogged
Let us assume that above points are okay and pump is producing flow, so now times to search for pressure. As we know that pump never creates pressure but also pressure will be developed if there is any resistance in the path of fluid flow .If resistance is low , pressure at that point will be low and suppose if resistance at a point is high then at that point pressure will be higher.

First we will check the pressure from a given pressure check point over the pump to know that what exactly pressure we are securing from the pump. If we are securing the correct pressure as specified by manufacturer or maintenance manual then we will go ahead to search the point where flow of pump is leaving the circuit by considering the concept of hydraulics that a fluid flow will follow a path where resistance in fluid flow is lower. 

We may secure the location or point where flow leaves the circuit if we have ability to read the hydraulic circuit diagram. 

 
Finally we may say that whether hydraulic system is simple or complex and problem seriousness is high or low, if we are following the basic concepts of hydraulics , we can easily secure the root cause.

In my point of view, there are three basic hydraulic system problems as mentioned below
  1. Abnormal Noise
  2. Slow operation
  3. Higher fluid temperature
We will discuss above hydraulic system problem and its root cause in my next post

So, let us go ahead towards next post to discuss the above problems in details with its root cause and the respective solutions.

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