中英文对照外文翻译文献
(文档含英文原文和中文翻译)
外文：
An Experimental Analysis of Brake Efficiency Using four
Fluids in a Disc Brake System
ABSTRACT
The paper studies disc brake failure in Mini-buses using an experimental analysis to
test the maximum braking force when different brake fluids such as clean, less dirty, dirty and soapy water solution were used in the braking system. The experimental results clearly showed that the soap solution appears to be the best fluid as far as low viscosity and stability of viscosity with increase in temperature are concerned. However, the soap solution is not compatible with other fluid which makes it difficult to be substitute as a clean brake fluid. The result of the Thepra Universal Brake Testing Equipment used for the braking efficiency test indicated that a pedal brake of 117 kN produce a brake force of 0.96 kN for clean brake fluid, 0.91 kN for the less dirty, 0.85 kN for dirty and 1.44 kN for
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soap solution. The value of 1.44 kN which was achieved when the soap solution was used indicated a positive braking force and the indicating that soap solution could be used to produce a high pedal force within a very short time (about 10-30 min) and can therefore be used only in case of emergency. The brake efficiency test indicated that under hot conditions the braking efficiency is reduced and the presence of air in the system renders the braking ineffective because higher pedal force was needed to be able to produce a significant braking force which is noted for causing brake failure.
Keywords: Brake fade, brake failure, disc brake, efficiency, pedal force INTRODUCTION
When a vehicle is accelerated, energy supplied by the engine causes the vehicle’s speed to increase. Part of this energy is instantly used up in overcoming frictional and tractive resistance but a large amount of it remains stored in the vehicle. According to Heinz (1999) this energy of motion is called the kinetic energy and the existence of kinetic energy is observed when a vehicle is moving and neutral gear is selected. The vehicle does not immediately come to rest; instead it travels for a considerable distance before it becomes stationary. In this case the stored energy is used to drive the vehicle against the resistances that oppose the vehicle’s motion. Relying on these resistances to slow down a vehicle could cause many problems, so an additional resistance called a brake is needed to convert the kinetic energy to heat energy at a faster rate in order to reduce the speed of the vehicle Mcphee and Johnson (2007). This reduces the speed of the vehicle at a faster rate and brings the vehicle to rest within the shortest possible time when the brakes are applied.
From the point of view of Johnson et al. (2003) most automotive systems in use today utilize front disc brakes, but four-wheel disc systems are also common In disc brakes, the rotor rotates with the wheel and the pads move out to rub the rotor when the brakes are applied. Most disc brakes use floating calipers. The caliper slides in and out as the brakes are applied and released. The piston moves the inside pad out and pushes the outside pad into the rotor by sliding the caliper back toward the rotor.
The use of disc brakes to reduce speed or bring the vehicle to rest when in motion cannot be over emphasized if the safety of the occupant is to be guaranteed Heinz (1999). To bring a vehicle to a stop, the disc brakes have to absorb all the energy given to the
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vehicle by the engine and that due to the momentum of the vehicle. This energy must then be dissipated. In most vehicle disc brakes, the energy is absorbed by friction, converted into heat and the heat dissipated to the surrounding air (Thoms, 1988). As the energy is absorbed, the vehicle is slowed down; in other words, its motion is retarded. The brakes must also pull up the vehicle smoothly and in a straight line to bring the vehicle to a stop position.
It is therefore very important that the disc brakes of vehicles operate with the highest efficiency. This could
reduce the rate of accidents due to brake failure so that life and property could be preserved and also to ensure that occupants of these commercial vehicles go about their normal lives without any fear of being involved in an accident. Available crash data in Ghana suggests that about 1,900 persons are killed annually in road traffic crashes (Afukaar et al., 2008) and that more than 40% of the road traffic fatalities are occupants of cars, buses and trucks. Most often than not, some of the road accidents involving commercial vehicles, such as the mini-buses have been attributed to the failure of the disc brakes. The reason for testing the viscosity of these brake fluids, especially that of the soap solution was as a result of the practice of most Ghanaian drivers sometimes using the soapy solution as a substitute to the original brake fluid in the braking system and also using dirty brake fluid which has been used for bleeding purposes. The main objective of this study which is part of a larger work seeks to investigate and establish the reasons for the disc brake failure due to brake fluid also check the efficiency of the four different types of fluids used in the transmission of braking forces. The study looked at the maximum braking force when using clean, less dirty, dirty and soapy water solution in the braking system. It also looked at the braking force when the braking system is with or without servo unit and operating under cold or hot condition with air or without air in the braking system DISC BRAKES
The disc brake consists of an exposed disc which is attached to the hub flange; the two friction pads are
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盘式制动器中英文对照外文翻译文献
