Roller bit with prevent falling device

The utility model relates to a drilling tool technical field especially relates to a roller bit with prevent falling device, include gear wheel shaft hole, bit leg axle, prevent falling device, staff sealing system, steel ball locking system and macroaxis sealing system, the bit leg axle is installed in the gear wheel shaft hole, steel ball locking system arranges in the gear wheel shaft hole with between the bit leg axle, the staff sealing system is located the root of bit leg axle for sealed gear wheel shaft hole and bit leg axle, it prevents falling the device standing groove to be equipped with between gear wheel shaft hole and the bit leg axle, it arranges in to prevent falling the device prevent falling in the device standing groove, it is circlip to prevent falling the device, circlip has the opening. This roller bit has and prevents falling the device, and it is very little to prevent falling the shared bearing space of device, and single roller bit weight on bit when using is low simultaneously to single roller bit diameter is also great, does not consequently influence the ability that the bearing held the loading lotus.