PICK HOLDER AND PICK BOX ASSEMBLY

摘要

A semi-locking pick box assembly (10) comprises a pick holder (30), a hydraulic seal (40) and a closed pick box (50). The pick holder has a frusto conical shank (33) with a base (34) and the closed pick box (50) has a shank chamber (51), a piston chamber (52) and a hydraulic duct (54). The shank chamber (51) matches the shape of the frusto conical shank (33) so that the pick holder (30) can lockingly fasten to the closed pick box (50) when the pick holder and closed pick box are engaged. The piston chamber (52) communicates with the shank chamber (51) and houses the hydraulic seal (40) so as to form a hydraulic piston which can act on the base of the frusto conical shank. The hydraulic duct (54) communicates between the piston chamber (52) and externally of the closed pick box (50) so that hydraulic pressure can be applied via the hydraulic duct (54) to the hydraulic seal (40) to cause the pick holder (30), when lockingly engaging the closed pick box (50), to move axially and be released from the closed pick box (50).