Nexen PRD1100 966902 - Manual (Page 5)

5 FORM NO. L-21274-A-0113
SYSTEM DESIGN OVERVIEW
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• Unlike traditional gear systems, the Roller Pinion Gear (RPG) rotary drive system has zero mechanical clearance and
requires a system preload for proper operation. This preload must remain relatively constant around the entire gear
to obtain optimal system performance and life. See Figures 1 and 2 for more details.
• Make sure that the machine design is rigid enough to avoid deflection that could affect the RPG system preload.
• The allowed ring gear concentricity variance tolerances shown in Figure 2 are greater than the system preload. This
is not an error. The RPG system has been designed to operate correctly under these conditions.
• The RPG System generates a reaction force that tries to separate the pinion from the gear teeth. Make sure this is
accounted for in the machine design. See product data for pressure angle specifications.
• The RPG System requires a mechanism to achieve proper pinion preload. It is recommended that the pinion be moved
into the gear not vice versa. The recommended method is to mount the servo drive system on a sliding bracket that
has an adjustment to push it into the gear. Another possible preloading method utilizes a bracket with an eccentric
mounting slot pattern. Nexen offers a preloading mechanism that is easy to integrate into your application as shown
in Figure 11. Spring loaded preloading mechanisms should not be used since the spring force required to counteract
the separation forces are much higher than the allowed preloading force and would cause a reduction in pinion needle
bearing life, and increase system noise. See Figure 11 for more details.
• The RPG System requires periodic lubrication and should use the grease offered on Nexen’s website as an accessory
to the RPG products or equivalent lubrication as described in the Lubrication section on page 16. For more information
or applications with special lubrication needs consult Nexen.
• Do not use the RPG System in environments with temperature outside of -5 to 40º C (23 to 104º F)‚ or with wide
temperature swings since this can affect the preload and meshing of the system. If you have an application with any
of these characteristics consult Nexen.
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• Install the RPG-B system at the temperature at which it will be used.
• The ring gear teeth are hardened on the tooth faces only.
• Make sure the machine design is rigid enough to avoid deflection that could affect the ring drive system.
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• Verify the shaft variance and diameter tolerances meet Nexen specifications before mounting the pinion. See Figure
3.
• The shaft on which the pinion is mounted on must pass all of the way through the pinion and bushing for proper
support.
• If using a flange mount pinion, verify that the dimensions and tolerances of the gearhead flange meet the specifications
of the ISO 9409 Standard.
• Mount the pinion as close to a support bearing as possible to minimize shaft deflection.
• The pinion roller bearings are sealed. It is still recommended, however, that the pinion be shielded from liquids, dust,
and debris.
• Multiple pinions can drive a gear without an additional service factor but the load sharing by each pinion must be equal.
This is best accomplished with discrete drives linked electronically; mechanically linking pinions is not recommended.
Contact Nexen for more information.
• The RPG system can be operated such that the pinion revolves around the ring gear as long as the pinion preload
remains within specifications as it revolves.