Hydraulic braking system is comprised of a prefill valve,a energy accumlator,a foot valve,caliper disc brake,( or other types of brakes),and the brake tail light switches,the presure switches.After filling the energy accumlator with the presure oil through the prfill valve,the presure oil directly goes into the foot valve.Actually the foot valve is a ratio reversing foot valve,the the prusure oil enters into the brake which is near the tyre.When the brakeage is not enough,the the energy accumlator supplies the oil..
There is another type,which is to brake with gas pushing liquid.The vacuum booster in the engine produces gas presure so as to push the brake oil cylinder,the oil in the brake oiler then enters into the brake oil cylinder,which is to increase the power,finally the oil enters the brake.
At present,the most brakes are disc brakes,not the drum brakes.
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