【单选题】编制 T68 型镗床主轴部件装配工艺过程应以本厂现有设备、工装等具体( )来制定。
【单选题】图示机构,以整体为对象,以下所列的平衡方程中,哪一个是正确的
A.
å X = X O - N × cos30 ° =0
B.
å m O (F) = m - P × r × sin30 ° =0
C.
å m O (F) = - m + N B × L =0
D.
å m O (F) = - m + N B × (L + r/ Ö 3) + N C × (2L + r/ Ö 3) = 0
【单选题】如图所示,转轴直径d=0.36m,轴承长度 l=1m,轴与轴承之间的间隙δ=0.2mm,其中充满动力粘度μ=0.72Pa·s的油,如果轴的转速n=200 r/min,求克服油的粘性阻力所消耗的功率。
【单选题】图示机构,以整体为对象,以下所列的平衡方程中,哪一个是正确的
A.
å m O (F) = - m + P × b =0
B.
å m O (F) = - m + N A × b/cos q + N D × L =0
C.
å m O (F) = - m + P × b + N D × L =0
D.
å m O (F) = - m + P × b + N A × b/cos q + N D × L = 0
【单选题】以下有关隧道的说法中,错误的是( )。
C.
软土隧道常常修建在水底和城市立交,故称为水底隧道和城市道路隧道
【单选题】The age of mandatory retirement is linked to most people's abilities.
【单选题】图示机构,以整体为对象,以下所列的平衡方程中,哪一个是正确的
A.
å m B (F) = m + P × 2L =0
B.
å m A (F) = m + P × 3L /4 = 0
C.
å m A (F) = m + P × 3L /4+ N E × L/4 =0
D.
å m B (F) = m + P × 3L /4 - Y A × L - X A × L × Ö 3/2=0