1. Apparatus for lifting a mold relative to a support member, comprising in combination: a. plural lifting means each including a lift cylinder stationary relative to said support member and a lift piston movable therein for actuation between lowered and raised positions for lifting said mold when actuated to said raised position; b. means biasing each of said lift piston to said lowered position; and means for actuating said lift pistons in unison to said raised position comprising: i. a liquid reservoir, ii. plural branch cylinders each in liquid communication with a different one of said plural lift cylinders below said lift piston in its lowered position, iii. piston means in each said branch cylinder having a liquid passageway extending therethrough and selectively in liquid communication with said reservoir, iv. means biasing each said branch piston to a reference position remote from the lift cylinder communicating end of said branch cylinder; v. normally open poppet valve means with each said branch piston for selectively closing said passage therethrough, and vi. selectively actuable pressure responsive means for actuating said poppet valve means to the closed state and for moving said branch pistons only in unison toward the lift cylinder communicating end of said branch cylinder.

3. Apparatus for lifting a mold relative to a support member, comprising in combination: a. plural lifting means each including a lift cylinder stationary relative to said support member and a lift piston movable therein for actuation between lowered and raised positions for lifting said mold when actuated to said raised position; b. means biasing each of said lift piston to said lowered position; and c. means for actuating said lift pistons in unison to said raised position comprising: i. a housing; ii. a liquid reservoir in said housing including an air space therewithin; iii. plural branch cylinders in said housing, each in liquid communication at one end with said reservoir and at the other end with a different one of said plural lift cylinders below said lift piston in its lowered position, iv. piston means in each said branch cylinder having a liquid passageway extending therethrough, v. means biasing each said branch pistons toward said reservoir communicating end of said branch cylinder, vi. a main atuating piston in fluid communication with said reservoir and selectively fluidly actuable into simultaneous driving engagement with all said branch pistons for moving said branch pistons only in unison toward the lift cylinder communicating end of said branch cylinder and normally biased out of said driving engagement therewith, vii. normally open valve means for each said branch piston for closing said liquid passageway therethrough during all movement of said branch piston toward the lift cylinder communicating end of said branch cylinder, whereby liquid displaced from each said branch cylinder by said moving branch piston overcome said lift piston biased to proportionally displace each respective lift piston, and viii. an air vent tube extending between said air space within said reservoir and the atmosphere, whereby liquid in said reservoir is maintained substantially at atmospheric pressure during actuation of said main actuating piston.

4. Apparatus for lifting a mold relative to a support member, comprising in combination: a. plural lifting means each including a lift cylinder stationary relative to said support member and a lift piston movable therein for actuation between lowered and raised positions foir lifting said mold when actuated to said raised position; b. means biasing each of said lift pistons to said lowered position comprising: i. a first liquid reservoir, ii. fluid conduit means connecting said first reservoir with said lift cylinders above said lift pistons in their raised positions, iii. a source of pressurized gas, and iv. means for applying said pressurized gas to said first reservoir to pressurize liquid therein; and c. means for actuating said lift pistons in unison to said raised position comprising: i. a housing, ii. a second liquid reservoir in said housing, iii. plural branch cylinders in said housing, each in liquid communication at one end with said second reservoir and at the other end with a different one of said plural lift cylinders below said lift piston in its lowered position, iv. piston means in each said branch cylinder having a liquid passageway extending therethrough, v. means biasing each said branch piston toward said reservoir communicating end of said branch cylinder, vi. a main cylinder in said housing, vii. a main actuating piston slidably movable within said main cylinder and actuable into simultaneous driving engagement with all of said branch pistons for moving said branch pistons only in unison toward the cylinder communicating end of said branch cylinder, viii. means for selectively applying said pressurized gas to said main cylinder to control actuation of said main actuating piston, and ix. normally open valve means with each said branch piston for closing said liquid passageway therethrough during all movement of said branch piston toward the lift cylinder communicating end of said branch cylinder, whereby liquid displaced from each said branch cylinder by said moving branch piston overcomes said lift piston bias to proportionally displace each respective said lift piston.