Service and Repair Manual June 2017Boom Components54 SX-180 Part No. 12684974-4Extension CylindersThe primary boom extension cylinder is locatedinside the boom assembly and incorporates cablesand pulleys that are responsible for extending theboom tubes. The secondary boom extensioncylinder is located underneath the number 0 boomtube and is responsible for extending the number1 boom tube. The extension cylinders are equippedwith counterbalance valves to prevent movement inthe event of a hydraulic line failure.How to Remove the PrimaryBoom Extension CylinderBodily injury hazard. Thisprocedure requires specific repairskills, lifting equipment and asuitable workshop. Attemptingthis procedure without these skillsand tools could result in death orserious injury and significantcomponent damage. Dealerservice is strongly recommended.Note: When removing a hose assembly or fitting,the O-ring (if equipped) on the fitting and/or hoseend must be replaced. All connections must betorqued to specification during installation. Refer toSpecifications, Hydraulic Hose and Fitting TorqueSpecifications.1 Raise the boom to a horizontal position andfully retract the primary extension cylinder.2 Remove the retaining fasteners from the boomend cover at the pivot end of the boom.Remove the cover from the machine.3 Tag and disconnect the limit switchharnesses. Remove the fasteners to the limitswitch harness mounting bracket and removethe bracket.4 Tag and disconnect limit switch 3RO (6).Remove the mounting bracket with the limitswitch attached. (Illustration 1)5 Disconnect and remove the stringpotentiometer from boom tube #0. Removethe clevis from boom tube #2.6 Tag and disconnect the harness from cabletension limit switch 6S (4). Remove thebracket and limit switch. Remove cabletension limit switch 5S (5) from the mountingbracket. (Illustration 1)Note: The mounting bracket must remain attachedto the extend cylinder.7 Tag, disconnect and plug the hydraulic hosesfrom the primary boom extension cylinder.Cap the fittings on the cylinder.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.8 Remove the fasteners from the inner cabletrack mounting bracket at the primary boomextension cylinder.
