Part No. 102521 S-40 • S-45 4 - 23October 2013 Section 4 • Repair ProceduresBOOM COMPONENTS4-5Platform LevelingMaster CylinderThe master cylinder acts as a pump for the slavecylinder. It is part of the closed circuit hydraulicloop that keeps the platform level through theentire range of boom motion. The master cylinderis located at the base of the boom.How to Remove the PlatformLeveling Master CylinderNote: When removing a hose assembly or fitting,the O-ring on the fitting and/or hose end must bereplaced and then torqued to specification duringinstallation. Refer to Section Two,Hydraulic Hoseand Fitting Torque Specifications.1 Remove the turntable end cover to access themaster cylinder.2 Raise the boom until the master cylinderrod-end pivot pin is accessible.3 Tag, disconnect and plug the master cylinderhydraulic hoses. Cap the fittings on thecylinder.Bodily injury hazard. Sprayinghydraulic oil can penetrate andburn skin. Loosen hydraulicconnections very slowly to allowthe oil pressure to dissipategradually. Do not allow oil tosquirt or spray.4 Attach a lifting strap from an overhead crane tothe lug on the rod end of the master cylinder.5 Remove the pin retaining fasteners from themaster cylinder barrel-end pivot pin.6 Place a rod through the barrel-end pivot pin andtwist to remove the pin.7 Remove the pin retaining fastener from the rod-end pivot pin.8 Use a soft metal drift to remove the pin.9 Remove the master cylinder from the machine.Crushing hazard. The mastercylinder could become unbalancedand fall if it is not properly attachedto the overhead crane.Property of American Airlines
