Hydraulic chuck assembly

A hydraulic chuck assembly to be provided on one end of a shaft of a lathe, comprising:

• a hollow main chuck body defining a fluid working chamber, said main chuck body having a rear closed end and a front head anterior to said fluid working chamber and being formed with a plurality of radially extending and angularly spaced seat retaining slide grooves;
• a tubular shaft sleeve to be sleeved on said shaft of said lathe, said shaft sleeve extending into said main chuck body and passing through said fluid working chamber;
• a tubular plunger movably provided inside said fluid working chamber and around said shaft sleeve, said plunger having a rear end portion and a gradually expanding and forwardly extending funnel-shaped cam portion extending out of said fluid working chamber and into said front head;
• a plurality of grip seats each being slidably retained in a respective one of said slide grooves, each of said grip seats having a rear side formed with an inclining groove, said inclining grooves of said grip seats cooperatively receiving said funnel-shaped cam portion;
• and
• a hydraulic driving means associated with said main chuck body and operating inside said fluid working chamber so as to move said plunger forward or rearward, said funnel-shaped cam portion camming said inclining grooves of said grip seats so as to move said grip seats toward or away from each other along said slide grooves.