Category: Brake system

Automotive Service Technicians and Mechanics Brake Performance Test of an Automobile

The brake performance test of FMVSS 105 defines the minimum needs for the brake system on any vehicle driven on the road. The technician should know a bit about the performance test, not for the sake of being able to quote government regulations. Parts of the test define the kind of performance a brake system should deliver after the vehicle serviced. The brake performance test divided into eighteen stages and begins with a new set of brakes on a test vehicle. The first stage is to install the test instruments on the vehicle and verify that they operate correctly. The vehicle then goes through the test called “first effectiveness test”. This test is performed with new brake linings before they have had a chance to burnish in.

Rules and Regulations for driving an automobile

The vehicle makes six stops from 30 mph and six stops from 60 mph. One of the stops from 30 mph made in 57 feet or less. One stop from 60 mph must be in 216 feet or less. These stopping distances and stopping distances in other stages of the test are absolute requirements for any vehicle of any size and weight. Remember that FMVSS 105 defines minimum brake performance. It is up to the engineers to design the vehicle and the brake system to meet the performance standards.

While the governments set the minimal rules and regulations for design and manufacturing, the technician should understand the ramification if a brake system is not returned to its designed capability. Failure to follow correct repair procedures could cause a vehicle accident, resulting in damage, injuries, and lawsuits. It takes less time to do it right, rather than to take a shortcut that saves time and labor in the short term. But it may result in much greater loss of time and money later.

Automotive Service Certification – ASE

After new vehicles are first sold, the responsibility for maintaining safe brake operation falls on the vehicle owners. The owners, in turn, rely on the service technician to keep the brakes in proper operating condition. Many states and provinces have laws that govern brake system operation and brake service. Some states require periodic vehicle safety inspection, either every year or every 2 years.

These safety inspections usually include at least an inspection of brake components. Some also include dynamic stopping tests, done on a brake system analyzer or on a measured course. If a vehicle fails any part of the safety inspection, its registration cannot be renewed till all defects are fixed. Some states require that a vehicle that failed a brake test or inspection, it cited for unsafe brakes by a police officer. The vehicle repaired at a state-authorized repair facility only. Moreover, some states, provinces, counties, or cities have regulations for the licensing or certification of brake service technicians. Some areas conduct their own certification programs; others rely on Automotive Service Excellence (ASE) certification in brake service. ASE is a nonprofit organization that technically certifies automotive technicians with a series of standardized written tests.

Automotive business leaders, technicians, and educators select and write the test questions. Working in an area that has brake service regulations, the technician will find that safety is not only good common sense, it is good business. Service technicians who pass all certification requirements for brake systems will get more of the service business, have more secure employment, and earn higher wages. As a result, any technician who provides high-quality brake service can take satisfaction in knowing that he or she is contributing to driving safety.

Automobile Engineering Brake system

Hydraulic Brake System of an Automobile | Construction and Working of Hydraulic Braking System | Components of an Oil Brake System

By magnaparthi on 06/05/202006/05/2020

Construction and Working of a Hydraulic Brake System of an Automobile

Hydraulic operation of the brake systems has been the universal design for more than 60 years. The complete components of oil or hydraulic braking system consists of master cylinder; steel lines, rubber hoses, various pressure-control valves, and brake apply devices at each wheel.

Master Cylinder

The master cylinder is the start of the brake hydraulic system. It actually is a cylindrical pump. The cylinder closed at one end, and the flexible push rod extends from the other end. The push rod moves a pair of in-line pistons that produce the pumping action. The brake pedal lever moves the push rod this moves the pistons to draw fluid from a reservoir on top of the master cylinder. Piston action forces the fluid under pressure through outlet ports to the brake lines.

All master cylinders for vehicles built since 1967 have two pistons and pumping chambers. Motor vehicle safety standards involve this dual-brake system to provide hydraulic system operation in case one wheel brake assembly loses fluid. Because the brake hydraulic system closed, all the lines and cylinders are full of fluid at all times. The master cylinder develops system pressure the amount of fluid moved is only in less value.

Split Systems

Modern-day vehicles have split brake systems. The pre-1970’s vehicle had a single hydraulic system serving all four wheels. A leak anywhere in the system will result in a complete braking failure. The split system designed to prevent total system failure. This required the use of a dual-piston master cylinder and the inclusion of various valves. A split system is fed by one piston in the master cylinder and feeds two wheel brakes of the vehicle.

There are two types of split systems: diagonal and front/rear. The diagonal system has one system feeding a front-wheel brake and the rear opposing side wheel brake, that is left front and right rear. The second triangle split is to the other wheel brakes. One side or split feeds the rear-wheel brakes and the other feeds the front wheels. Both of these types have advantages and disadvantages, but each prevents complete system failure from a single leak.

Brake Lines and Hoses

The rigid lines or pipes of a brake hydraulic system made of steel tubing for system safety. Flexible rubber hoses join the wheel brakes to the rigid lines on the vehicle body or frame. The front brakes have a rubber hose at each wheel to allow for steering movement. Rear brakes may have different hoses at each wheel or a single hose connected to a line on the body or frame if the vehicle has a rigid rear axle. Brake lines and hoses contain the high-pressure fluid, and the fluid acts like a solid rod to transfer force to the wheel cylinders and caliper pistons.

Wheel Cylinders and Caliper Pistons

Technically, the wheel cylinders of drum brakes and the caliper pistons of disc brakes are “slave” cylinders because they operate in response to the master cylinder. These hydraulic cylinders at the wheels change hydraulic pressure back into mechanical force to apply the brakes. Most late-model systems with drum brakes have a single, two-piston cylinder at each wheel. Hydraulic pressure enters the cylinder between the two pistons and forces them outward to act on the brake shoes. The shoes move outward, the lining contacts the drums to stop the car.

Hydraulic or Oil Braking system in Automobile

The caliper pistons for disc brakes also act in response to hydraulic pressure that enters a fluid chamber in the caliper. Hydraulic pressure in stationary caliper is applied to one or two pistons on each side of the caliper to force the pads against the rotor. Pressure is applied to a single piston in a movable caliper on the inboard side to force the inboard pad against the rotor. Hydraulic pressure is equal in all directions in a closed chamber. This equal pressure creates a reaction force that moves the outboard side of the caliper inward so that both pads grip the rotor.

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