Industrial lift trucks

Claim 1

An industrial lift truck comprising: a mast structure; a load lifting carriage movable up and down said mast structure; a turret head mounted on said load lifting carriage for sideways movement relative thereto; a load supporting structure mounted on said turret head for rotation relative thereto about an upright axis; an electric motor mounted on said turret head; a switch controlling the operation of said motor; a reversible transmission, said motor being drivably connected to said load supporting structure for rotating same through said reversible transmission; a releasable frictional brake assembly comprising a pair of brake callipers, and spring means for biasing said callipers into braking engagement with a cylindrical member which is rotatable with said transmission so as to restrain it against movement; and means for releasing said brake assembly when said motor is operated, said means comprising an electrically operated solenoid, and a switch controlling the operation of said solenoid, said switch being coupled for simultaneous operation with said first-mentioned switch controlling said motor, so that operation of said solenoid produces movement of said callipers out of braking engagement with said member against the action of said spring means when said motor is opeRated, whereby the brake assembly is selectively operable to hold said load supporting structure in any desired position, including three working positions whereat said load supporting structure is directed forwardly or to either side, further said brake callipers serving as an overload device to permit frictional rotation of said cylindrical member if sufficient external force is applied to said cylindrical member.