图3-11所示为变量液压泵和定量液压马达系统,低压辅助液压泵输出压力P y =0.4MPa,变量泵最大排量V pmax =100mL/r,转速n P =1000r/min,容积效率η VP =0.9,机械效率η mP =0.85。马达的相应参数为V M =50mL/r,η VM =0.95,η mM =0.9。不计管道损失,试求当马达的输出转矩为T M =40N·m、转速为n M =160r/min时,变量泵的排量、工作压力和输入功率。
【单选题】Part I Multiple-choice Directions: Listen to the whole passage and choose the best answer from the four choices marked A, B, C and D. 1. How many US troops died in August in Afghanistan according t...