Brake Fluids

Brake fluids are responsible for the movement of the various components of the braking system. It is responsible for the transmission of pressure from one part to another. It is very easily neglected by many of us these days. We change the engine oil, radiator fluid, transmission fluid. We even change the air conditioning coolant, but somehow we don't change the brake fluid.


It operates at high temperature and high pressure. We call the braking system a closed system as none of the brake fluid will neither enter nor leave the system. Nor does anything get consumed.

     They are basically five types of brake fluids.

          1. DOT 2
          2. DOT 3
          3. DOT 4
          4. DOT 5
          5. DOT 5.1


The most common types of brake fluid are the DOT 3, DOT 4 and DOT 5.1. DOT 5 is used in rare cases. Even DOT 2 is not widely used.
Brake fluids have to meet certain quality standards like SAE International or US DOT (Department of Transport).
Dry boiling point is the boiling temperature of fresh brake fluid. Wet boiling point is the boiling temperature of braking fluid after absorbing 3.7% of water by volume. If you notice the dry boiling point is always greater than the wet boiling point of the oil.
 Brake fluids usually absorb that much amount of water after 1-2 years and that is why it is recommended to change your brake fluid after 2 years. DOT 2 is just castor oil based and has the lowest dry and wet boiling point of all the brake fluids.


The bake fluids having different DOT ratings should not be mixed. For example, DOT 3 can be replaced with either DOT 3 or DOT 4 or DOT 5.1. DOT 4 can be replaced with DOT 5.1. It is recommended not to use a lower rating fluid. Never mix DOT 5 with DOT 3 or DOT 4 or DOT 5.1.

.

Comments

Post a Comment

Popular posts from this blog

3 spool vs 2 spool

Image
In the Trent 1000, there is 3 spool arrangement of compressors and turbines. This means that there are three sets of compressors and turbines which are connected by three separate shafts. They are the low pressure compressor (LPC) which is the fan and turbine (LPT), Intermediate pressure compressor (IPC) and turbine (IPT) and high pressure compressor (HPC) and turbine (HPT). This is on contrast to the two spool arrangement currently used in many aircrafts where a LPC/LPT and HPC/HPT are used only. All the three shafts are located within each other. The fan positioned at the front of the engine is run by the LPT via a gearbox so that it can operate at optimum speeds. Since the large diameter fan requires a large torque to start rotating, it limits the high speed attained by the LPT due to which its efficiency decreases. Additions of an additional set of compressor and turbine eliminates the influence of this problem but does not eliminate the problem itself! The problem is elim
Keep reading

Materials used in Turbine blades

Image
There has been a wide range of materials used for the manufacturing of gas turbine blades. It is one of the most important parts in a gas turbine and any deterioration of it will affect the performance and efficiency of the turbine and most importantly will damage the turbine.  Many materials have been tested and used but the most preferred materials include steel, titanium, Nickel based super alloys and ceramics. The first stage of the compressor is very delicate as it is subjected to a very high temperature of approx. 1400-1500 degree celsius.  This part of the turbine should tolerate high temperatures, high pressures, high thermal stresses including creep and fatigue, vibrations which can influence it's performance. The first stage uses Udimet 500, Nickel based super alloy Inconel 738 or GTD 111.  The relatively cold stages of the turbine employ titanium as there are chances of it igniting when used above 500 degree celsius.        Applications                
Keep reading

Self Energizing Brakes

Image
The usual drum brakes in our car are provided with a remarkable feature called 'servo' or 'self energizing' feature. It is this feature that is responsible for the smooth and flat application of brakes in automobiles. When the vehicle is moving left, in the forward direction, then the drum will rotate in the anticlockwise direction. When the brake pedal is suddenly pressed, the two brake shoes at the drum will have full contact with the drum. However, one of the brake shoes, the primary brake shoe tends to slip for a certain distance in the drum's direction. Due to this, the primary brake shoe will tend to apply a rearwards force on the secondary brake shoe at the bottom. The wheel cylinder at the top forces the piston against the top of both the brake shoes. Due to this, the secondary brake shoe experiences force on both the sides i.e the top and bottom side.  This ensures that the brakes are applied uniformly and much less effort is applied.
Keep reading