The utility model relates to a structure is reformed transform in main oil hole that becomes enlargement for do not changing main become oil hole volume and with the main prerequisite that becomes the cable channel position that the cooperation of oil hole set up under, realize the main body increase -volume that becomes, main the change lay main declension bars on the oil hole, main the change erect in main declension bars top, this oil hole reform transform structure be one set up the main surface course that becomes the oil hole and with the main oil groove of leading that becomes oil hole intercommunication, should lead the oil groove by enlargement grid, oil hole side wall with keep off the oil wall and surround and form, enlargement grid and main declension bars all set up at the main surface course that becomes the oil hole, fender oil cut off to set up and is leading between oil groove and the cable passage. Compared with the prior art, the utility model has the advantages of reduce the construction degree of difficulty and design cycle, improve the economic nature of engineering.