BRAKES ASSIGNMENT – LUKE WILSON 9977065 – CLASS CO3
PASCAL’S LAW
Pascal's law or the principle of transmission of fluid-pressure is a principle in fluid mechanics that states that pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure ratio (initial difference) remains the same. The law was established by French Mathematician, Blaise Pascal.
Pascal's principle is defined as: A change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid.
If a U-tube is filled with water and pistons are placed at each end, pressure exerted against the left piston will be transmitted throughout the liquid and against the bottom of the right piston. The pressure that the left piston exerts against the water will be exactly equal to the pressure the water exerts against the right piston. Suppose the tube on the right side is made wider and a piston of a larger area is used; for example, the piston on the right has 50 times the area of the piston on the left. If a 1 N load is placed on the left piston, an additional pressure (nearly 1 N/cm2) due to the weight of the load is transmitted throughout the liquid and up against the larger piston. The difference between force and pressure is important: the additional pressure is exerted against every square centimeter of the larger piston. Since there is 50 times the area, 50 times as much force is exerted on the larger piston. Thus, the larger piston will support a 50 N load - fifty times the load on the smaller piston.
Forces can be multiplied using such a device. One newton input produces 50 newtons output. By further increasing the area of the larger piston (or reducing the area of the smaller piston), forces can be multiplied, in principle, by any amount. Pascal's principle underlies the operation of the hydraulic press. The hydraulic press does not violate energy conservation, because a decrease in distance moved compensates for the increase in force. When the small piston is moved downward 10 centimeters, the large piston will be raised only one-fiftieth of this, or 0.2 centimeters. The input force multiplied by the distance moved by the smaller piston is equal to the output force multiplied by the distance moved by the larger piston; this is one more example of a simple machine operating on the same principle as a mechanical lever
Pascal's principle applies to all fluids, whether gases or liquids. A typical application of Pascal's principle for gases and liquids is the automobile lift. Increased air pressure produced by an air compressor is transmitted through the air to the surface of oil in an underground reservoir. The oil, in turn, transmits the pressure to a piston, which lifts the automobile. The relatively low pressure that exerts the lifting force against the piston is about the same as the air pressure in automobile tires.
TANDEM BRAKE MASTER CYLINDER
With a basic master cylinder in the braking system, any loss of fluid, say because a component fails, could mean the whole braking system fails. To reduce this risk, modern vehicles must have at least two separate hydraulic systems. That’s why the tandem master cylinder was introduced.
The two systems can be split front-to-rear, so that the front brakes operate from one circuit and the rear brakes from the other, or they can be split diagonally so that one front wheel is paired with the rear wheel on the opposite side in one brake circuit, and vice versa in the other.
Like two single-piston cylinders end-to-end, a tandem cylinder has a primary piston and a secondary piston. Each section of the cylinder has inlet and outlet ports, and compensating ports. There can be two separate reservoirs, or just one divided into separate sections.
When the brake is applied, the primary piston moves, and closes its compensating port.
