Nexen RPG25A-GE486T 966740 - Manual (Page 14)

FORM NO. L-21235-G-0413 14
APPLYING PRELOAD
If you would prefer to not design your own pinion
preloading mechanism, Nexen offers a high precision push
bolt preloading system that bolts between the machine
frame and servo reducer to simplify machine design and
achieve optimal results. See figure 18. Preloading Procedure
Note: Be careful engaging the pinion and servo assembly
to the rack to avoid damaging the rack teeth or pinion
rollers.
1. With a dial indicator mounted on the movable carriage,
measure off the tooth peaks. Move the carriage down
the run taking frequent measurements to locate the
high spot in the run. This is where the pinion preloading
should be done to prevent excessive preload from
occurring elsewhere in the run.
2. Apply serviceable thread locking compound to the
pinion preloader slider bolts and install the servo and
preload mechanism. Ensure the preload related bolts
are just loose enough to allow the pinion to be pulled
away from the rack teeth. For the Nexen Preloader
System, this is approximately 0.2 - 0.3 Nm [2 - 3 in-
lbs].
Nexen Precision Pinion Preloader product numbers and
more information can be found at www.nexengroup.com
on any of the RPS pinion pages under accessories in the
left hand column.
To ensure optimal meshing of the roller pins with the
rack teeth, the shaft must be preloaded to 0.010 - 0.015
mm [0.0004 - 0.0006 in] beyond full roller/tooth root
engagement.
NOTE: Do not apply excessive preload. Preloading
beyond 0.015 mm [0.0006 in] will decrease product
life, increase noise, and cause vibration. When the
RPS system is properly preloaded, there will be no
tangential play between the rack and the pinion if the
pinion is not allowed to turn and the carriage assembly
forced back and forth in the direction of travel.
Refer to Figure 19 for suggested preload methods.
Figure 18
17. Re-torque the mounting screws once more to the full-
specified torque value in Table 4 to ensure full torque
has been reached on all fasteners. Tighten in the same
order as in Step 16.
Nexen Precision
Pinion Preloader
Customer
Machine Frame
Gearhead
Nexen Roller
Pinion
Figure 19 Customer Designed Pinion Preloaders
Adjustment by Elongated Slots
(Preferred Method)
Adjustment by Eccentric Slots
Part #
Part #
Preload Adjustment
Screw
High Point In Rack Teeth
High Point In Rack Teeth
18. Repeat concentric runout inspection Step 15 and
verify concentric runout remains within specifications
after fully torquing the pinion. If the runout is out
of specifications the pinion should be removed
inspecting for contaminates, burs, or surface defects
that would interfere with full contact between the
pinion and adapter (if used) or gearhead flange.
Indexing the pinion relative to the adapter (if used) or
gearhead may help in some cases. Repeat the pinion
installation procedure starting with Step 13.