Nexen RPG25A-GE486T 966740 - Manual (Page 8)

FORM NO. L-21235-G-0413 8
1. Ensure that the mounting surface and rack are
completely clean, free of burrs, or anything that could
interfere with full contact with the mounting surfaces.
2. With the guiding system in place mount a dial indicator
on the carriage and measure the perpendicularity and
parallelism variance on the two rack mounting surfaces
by moving the carriage down the run and monitoring
the dial indicator readings. Verify they meet or exceed
specifications of ±0.03 mm [±0.001 in.] as shown in
Figure 4. If variance is not within specifications, verify
guiding system installation and correct if possible.
Mark the location of the high point in the mounting
surface the rack bottom sits on.
Figure 5
Part Number
Part Number Must Face Out
6. Once the rack mounting bolts are fully torqued, verify
tooth peak variance is less than ±0.03 mm [±0.001
in] by placing a dial indicator on the movable carriage
with the indicator tip on the tooth peaks. Measure
the tooth peak variance at points throughout the rack
section as shown in Figure 6.
If the tooth peak variance is out of specifications and
the mounting surface was in specifications dismount
the rack and inspect for dirt, burs, or anything that
would prevent proper rack to mounting surface
seating.
RACK INSTALLATION
Figure 4
Second Rack
First Rack
Part #
Part #
Figure 6
3. Start rack installation at the high point in the mounting
surface the rack bottom sits on. This may not be at
the end of the run.
Additional sections of rack will be shimmed as required
throughout the rest of the run to bring the rack tooth
peak variance into specifications relative to the first
rack section.
4. Apply a serviceable thread locking compound to the
customer supplied mounting bolts, lightly secure the
first rack length to the mounting surface and clamp it
in place while protecting the rack teeth by distributing
the clamp load over several teeth. Make sure the
clamps are close to each bolt as they are tightened
to ensure full rack to mounting surface contact. See
Figure 5. Socket head cap screws are recommended
for maximum pinion shoulder clearance. Make sure
the side of the rack with the part number on it is not
against the mounting surface and any cut rack ends
are at the end of the run.
5. Tighten the mounting bolts on the first rack alternately
and incrementally 10%, 50%, then fully torque,
working from the center of the rack towards the ends.
Refer to Table 2 for recommended tightening torques.
If the mounting surface is out of recommended
specifications then shimming between the rack bottom
and the mounting surface will be required. Locate the
high point within the rack section and shim all other
points to meet it.
When shimming, it is recommended to support the
rack as much as possible, not just short pieces near
mounting bolts.
Adding Additional Racks
NOTE: Alignment Tools for each RPS size are required
and available for purchase from Nexen. This tool
is required for proper installation of multiple rack
segment runs.
7. Butt the second rack segment against the first fully
secured rack on the mounting surface and lightly
secure it with fasteners with serviceable thread locking
compound applied so it is in full contact with the
mounting surface but still moveable within the rack
mounting hole tolerances.
8. Mount the Alignment Tool between the two racks
utilizing the adjacent tooth roots of each rack while
being careful not to damage the rack or alignment tool
as shown in Figures 7 and 8. The GEN B alignment
tool has a different appearance but functions the same
and has no bolt down provisions. It is hand pressed
into place to set the rack spacing as described on the
next page.