Nexen HGP25 969053 - Manual (Page 8)

FORM NO. L-21277-B-1213 8
RACK INSTALLATION
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 6. 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 7
Part Number
Part Number Must Face Out
Figure 6
5. Tighten the mounting screws on the first rack
alternately and incrementally 10%, 50%, 100% then
working from the center of the rack towards the ends.
6. Once the rack mounting screws are fully tightened,
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 8.
Second Rack
First Rack
Part #
Part #
Figure 8
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 screws, 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 a clamp is close to each screw as it is tightened
to ensure full rack to mounting surface contact. See
Figure 7. 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.
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.
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 screws.
a
ddinG
a
dditional
r
ackS
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. Position the end of the additional rack segment against
the end of the first fully secured rack on the mounting
surface and lightly secure with screws with serviceable
thread locking compound applied. The additional rack
should be in full contact with the mounting surface
but still moveable within the rack mounting hole
tolerances.