To Study the Basics of Crane(Ⅰ)

 
 Multiple choice
1.As for a steel rope with the diameter of 8mm, the points are fixed with the rope clamp, whose number should not less than (B)
  A．2   B．3   C．5 
2.The performing time of the brake of the lifting mechanism is (B), which can cause the phenomenon of objects falling off the hook.
 A．short   B．long 
3.The steel rope of (C) core is usually used in the crane.
 A．fiber  B．natural fiber   C．synthetic fiber   D．metal wire
4.The twisting direction of the  inner wire rope should be (A)
 A.in the same direction  B.alternating twist    C．mixed twist
5.The  tensile strength of the steel rope used in the crane should be ()/mm2.
 A．1400    B．1550-1850   C．2000
6.The smaller horizontal size of the (A) lifting hook is good for the declination without the limitation of the branch number. Thus, it is widely used.
 A．short hook   B．long hook  
7.The bridge crane adopts the brake of (A)
 A． block-type   B．draper-type    C. plate-type  
8.The lifting mechanism used for lifting the hot mental, should use the heat resisting steel rope of (B) core.
 A．fiber  B．natural fiber   C．synthetic fiber   D．metal wire  
9.In accordance with the arranging conditions of the cranes running gears, the brake of the running gears should be installed on the (A) shaft of the brake.
 A．input    B．output   C．middle 
10.In the working condition of humid air and acid gas erosion, the crane should use the galvanized steel wire rope, whose tensile strength should be(C).
 A．increase by 10%   B．decrease by 10％   C．satisfied with the requirement of performance