The remote control grab is more convenient and advanced than the hand-held grab. Why install the troublesome and backward hand-held device on the convenient and advanced remote control grab? There is no way to use the hand-held device as an emergency because of the failure of the remote control grab. The principle of remote control grab with hand pulling device is very simple: it is to install the upper part of the electromagnetic reversing valve and connect a thin wire rope on the headgear, so it has no advanced nature. Moreover, manual is only to solve the failure of the electrical part of the remote control grab, while the failure of the hydraulic part can not be solved by hand.