外文翻譯---制動系統(tǒng)-文庫吧
2025-01-02 23:24 本頁面
【正文】 e brake pedal is released, a spring pushes the master cylinder pistons back to their normal positions. Check valves in the master cylinder piston allow fluid to flow toward the wheel cylinders or calipers as the piston returns. Then as the brake shoe return springs pull the brake shoes back to the released position, excess fluid returns to the master cylinder through pensating ports, which have been uncovered as the pistons move back. Any fluid that has leaked from the system will also be replaced through the pensating ports.All dual circuit brake systems use a switch to activate a light, warning of brake failure. The switch is located in a valve mounted near the master cylinder. A piston in the valve receives pressure on each end from the front and rear brake circuits. When the pressures are balanced, the piston remains stationary, but when one circuit has a leak, greater pressure during the application of the brakes will force the piston to one side or the other, closing the switch and activating the warning light. The light can also be activated by the ignition switch during engine starting or by the parking brake.Front disc, rear drum brake systems also have a metering valve to prevent the front disc brakes from engaging before the rear brakes have contacted the drums. This ensures that the front brakes will not normally be used alone to stop the vehicle. A proportioning valve is also used to limit pressure to the rear brakes to prevent rear wheel lockup during hard braking.1. Friction materialsBrake shoes and pads are constructed in a similar manner. The pad or shoe is posed of a metal backing plate and a friction lining. The lining is either bonded (glued) to the metal, or riveted. Generally, riveted linings provide superior performance, but good quality bonded linings are perfectly adequate.Friction materials will vary between manufacturers and type of pad and the material pound may be referred to as: asbestos, organic, semimetallic, metallic. The difference between these pounds lies in the types and percentages of friction materials used, material binders and performance modifiers.Generally speaking, organic and nonmetallic asbestos pound brakes are quiet, easy on rotors and provide good feel. But this es at the expense of high temperature operation, so they may not be your best choice for heavy
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