Nexen RPS12 User Manual

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Nexen RPS12 User Manual Manual pdf 14 page image

FORM NO. L-21235-G-041314APPLYING PRELOADIf you would prefer to not design your own pinionpreloading mechanism, Nexen offers a high precision pushbolt preloading system that bolts between the machineframe and servo reducer to simplify machine design andachieve optimal results. See figure 18.Preloading ProcedureNote: Be careful engaging the pinion and servo assemblyto the rack to avoid damaging the rack teeth or pinionrollers.1. With a dial indicator mounted on the movable carriage,measure off the tooth peaks. Move the carriage downthe run taking frequent measurements to locate thehigh spot in the run. This is where the pinion preloadingshould be done to prevent excessive preload fromoccurring elsewhere in the run.2. Apply serviceable thread locking compound to thepinion preloader slider bolts and install the servo andpreload mechanism. Ensure the preload related boltsare just loose enough to allow the pinion to be pulledaway from the rack teeth. For the Nexen PreloaderSystem, this is approximately 0.2 - 0.3 Nm [2 - 3 in-lbs].Nexen Precision Pinion Preloader product numbers andmore information can be found at www.nexengroup.comon any of the RPS pinion pages under accessories in theleft hand column.To ensure optimal meshing of the roller pins with therack teeth, the shaft must be preloaded to 0.010 - 0.015mm [0.0004 - 0.0006 in] beyond full roller/tooth rootengagement.NOTE: Do not apply excessive preload. Preloadingbeyond 0.015 mm [0.0006 in] will decrease productlife, increase noise, and cause vibration. When theRPS system is properly preloaded, there will be notangential play between the rack and the pinion if thepinion is not allowed to turn and the carriage assemblyforced back and forth in the direction of travel.Refer to Figure 19 for suggested preload methods.Figure 1817. Re-torque the mounting screws once more to the full-specified torque value in Table 4 to ensure full torquehas been reached on all fasteners. Tighten in the sameorder as in Step 16.Nexen PrecisionPinion PreloaderCustomerMachine FrameGearheadNexen RollerPinionFigure 19 Customer Designed Pinion PreloadersAdjustment by Elongated Slots(Preferred Method)Adjustment by Eccentric SlotsPart #Part #Preload AdjustmentScrewHigh Point In Rack TeethHigh Point In Rack Teeth18. Repeat concentric runout inspection Step 15 andverify concentric runout remains within specificationsafter fully torquing the pinion. If the runout is outof specifications the pinion should be removedinspecting for contaminates, burs, or surface defectsthat would interfere with full contact between thepinion and adapter (if used) or gearhead flange.Indexing the pinion relative to the adapter (if used) orgearhead may help in some cases. Repeat the pinioninstallation procedure starting with Step 13.