单项选择题
A.time B.space C.length D.visibility
In a ordinary cargo crane, （） is fitted to rotate the c...
单项选择题In a ordinary cargo crane, （） is fitted to rotate the crane.
A.the slewing motor B.the lulling motor C.the hoisting motor D.none of the above
The single acting cylinder is the simplest form where p...
单项选择题The single acting cylinder is the simplest form where pressure is applied to the full area of the piston head to move the load through piston rod extensionThe load causes rod （） when the drive pressure is released.
A.contraction B.retraction C.expansion D.shrinkage
Among the basic categories of equipment, which of the f...
单项选择题Among the basic categories of equipment, which of the following are used to convert the hydraulic energy into linear motion?（）
A.Hydraulic pumps B.Valves C.Hydraulic cylinders D.Hydraulic motors
