## Saturday, 28 November 2015

We have already discussed the "Hydraulic Accumulator and its operating mechanism" . We have also discussed why we need hydraulic accumulator in our hydraulic circuit with the help of our previous post i.e. “Application of hydraulic accumulator”.

Today we are interested to see two very important types of hydraulic valve which is now in huge demand in hydraulic machinery or system. First one is hydraulic proportional valve and second one servo valve.

We will discuss here hydraulic proportional valve in this post and in next post we will see the concept of servo valve. So let us come to the main topic i.e. hydraulic proportional valves.

### Hydraulic Proportional valve

Proportional valve provides the infinite positioning of spool, therefore infinite adjustable flow volume will be secured by using hydraulic proportional valve in our hydraulic unit. Such types of valves are normally used in a hydraulic circuit that requires more than one speed of actuators.

Spools of proportional valves are designed with V-notches in order to secure the control over flow of fluid i.e. speed of actuator and also control over the direction of fluid flow by a single valve, therefore we do not need to use one valve to control the direction of fluid flow and another valve for controlling the flow of fluid or speed of actuator.

Proportional valves are normally preferred for such hydraulic units where we need to vary either pressure or flow in order to reduce shock or lunge. The solenoids of such hydraulic valve will move the spool less or more on the basis of the voltage which will be applied across the proportional solenoids and these variable electric signals will be produced by programmable logic controller or also by using a simple rheostat. Proportional valve controls deceleration or acceleration by varying the shifting time of spool.

Infinite positioning of spools will be secured by the applied voltage around the proportional solenoid.

Proportional valves will be operated by electrical signal and electrical power which will be used to operate the proportional valve will be DC power.

Let us go ahead toward next article / post.