Brake system

During take-off and landing, the wheels of modem aircraft are subject to great stress. New high-performance brake systems and aggressive environmental influences push the wheels closer and closer to their limit. These conditions as well as increased requirements for safety and quality control now necessitate that wheels are tested much more comprehensively than in the past. 

Many modem automobiles are now equipped with an antilocking braking system. Explain in terms of and fit why this is advantageous. 

Carbon Composites. Cermet friction materials tend to be heavy, thus making the brake system less energy-efficient. Compared with cermets, carbon (or graphite) is a thermally stable material of low density and reasonably high specific heat. A combination of these properties makes carbon attractive as a brake material and several companies are manufacturing carbon fiber—reinforced carbon-matrix composites, which ate used primarily for aircraft brakes and race cats (16). Carbon composites usually consist of three types of carbon carbon in the fibrous form (see Carbon fibers), carbon resulting from the controlled pyrolysis of the resin (usually phenoHc-based), and carbon from chemical vapor deposition (CVD) filling the pores (16). 

There is much interest and concern for noise/vibration-free brake systems and there is much activity toward friction couples having reduced noise/vibration properties. In addition to better noise insulators, brake modifications in the form of different materials, different designs, and improved friction materials formulations and/or processes are being developed and implemented. 

A. E. Anderson, "Brake Systems Performance—Effects of Eiber Types and Concentrations", Proceedings from Fibers in Friction Materials Symposium, Asbestos Institute, Atiantic City, N.J., Oct. 1987. 

Antilock braking systems with quickly reacting independent wheel decisions based on current and acquired knowledge... 

I In both the above types of braking systems, a hand-operated device is also provided, to release the mcehanieal brakes in applieations such as lifts, elevators, cranes, and winders. This... 

Today s eddy eurrent brake system is far superior to the meehanieal switeh-operated units of the past. Modern eontrols take advantage of all of the sophistieated logie found in mieroproeessor teehnology. This eontrol system is funetionally deseribed in Figure 4-147. Eaeh blaek box represents a separate eontrol funetion with a master eontrol ealled the eddy eurrent brake eontroller. ... 

Any trailers to be fitted with effective braking system acting on all wheels, actuated by the towing vehicle and automatically upon breakage of the coupling. Trailers equipped with only inertia braking devices limited to a maximum load of 50 kg net explosive mass... 

American engineer George Westinghouse introduces the air brake. The new power braking system uses compressed air as the operating medium. 

The drawworks basically contains the hoist drum, the transmissions, the brake systems, the clutch systems, rotary drive sprocket, and cathead. Figure 4-10 shows a schematic of the drawworks. 

In Figure 4-11, the driller s console is at the left of the drawworks. Also, the hoisting drum and sand reel can be seen. The driller s brake control is between the driller s console and the drawworks to control the brake systems of the hoisting drum. 

Table 4-121 gives the specifications compiled by manufacturers for several measuring devices. It can thus be seen that such devices must be equipped with an axial braking system capable of having a stroke of 10 and even 20 cm. 

With the modern ABS braking system contact temperatures are kept low, particularly on wet surfaces so that the log a v is relatively high and the silica-filled compound is superior to the standard black-filled one. With locked wheel braking the contact temperamres are high and log a-iv values are low, and the ranking of the braking performance of these two compounds reverses. 

Most engineers are aware of the importance of preventive maintenance programs, especially those owning automobiles or homes. A little neglect can cause serious property damage and may be the genesis of serious accidents for example, poorly maintained brake systems have inevitable consequences. 

In GM s Hy-wire hydrogen powered concept vehicle, there is a fuel cell for the power source and electronics replace mechanical parts in the steering and braking systems. The driver looks through a large, sloped windshield that covers space usually taken up by an engine. There is no dashboard, instrument panel, steering wheel or pedals, only a set of adjustable footrests. 

Transmission components, transmission thrust washers, braking and air-conditioning systems, ABS brake systems. .. 

Brake, hydraulic, and recoil-cylinder fluids fall in much the same field of operating conditions. These are employed in systems in which operating units are exposed to low temperatures, and in practically all cases the connecting tubing lines are so exposed. Temperatures are not likely to go very high, but for aviation, temperatures as low as —70° F. may be frequent. Practically all brake systems and many hydraulic systems employ reciprocating units packed with synthetic rubbers. Hydraulic systems employ rotary pumps and often rotary motors these cannot be soft packed but are only capillary-sealed—i.e., close clearances. These pumps and motors drop in volumetric efficiency as viscosity falls. 

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