ASME SRB-1 pdf free download

ASME SRB-1 pdf free download Design, Installation, Maintenance, and Application of Ball Slewing Ring Bearings
Calculation methods for gear strength are beyond the scope of this Standard. The reader is referred to gear designtextbooksandtoAGMA/ISO standards.Ifquestions arise regarding proper calculation methods, these should be discussed with the SRB manufacturer.
5.2.2 Addendum Modification. In some applications the pinion gear is cut with a modified addendum. The slew gear can also be cut with a modified addendum, but it is less commonly done. Addendum modification is the displacementofthe gear cuttingtoolfromthestandarddiametertoproducethicker or thinner teeth than standard. The tip (outside for an external, inside for an internal) diameter is modified to provide full contact without interference with the mating gear. The center distance can be smaller than, equal to, or greater than the standard distance for gears with unmodified addenda. Addendum modification can be used to eliminate undercutting and increase bending strength of gear teeth. Addendum modification is often required to avoid interference with gear sets having pinions with low numbers of teeth.
5.3 Mounting Design MostSRBsareinstalledwithaboltedjoint.Thedesignof this joint, consisting of the mounting surfaces, fasteners, andSRB, is critical to the properfunctioningofthe bearing and is the responsibility of the equipment manufacturer. The companion structures shall be designed and manu- factured to minimize out-of-flatness. Out-of-flatness shall be gradual when it occurs. Mountingholeswithinthestructureshallhavethesame quantity and position as the mounting holes in the SRB with adequate tolerance to prevent distortion of the bearing. The SRB support structure shall be sufficiently rigid and free of distortion during operation to avoid uneven or localized loading on the bearing. If the SRB design includes a locating pilot, the locating pilot shall be machined round.
A configuration where either the bearing race or the mounting surface is threaded is acceptable, as is drilling through both and using flat washers and nuts. For fixed center designs, the center distance spacing must take into account the tolerance stack up and runout ofboth the gears and the mounting arrangement. Foradjustablecenterdesign,backlashisadjustedatinstal- lation. Ata minimum, there mustbe sufficientbacklash to prevent interference throughout the slewing range. When the SRB is being designed, the lubricant ports should be located in the bearing race thatdoes notrotate.
5.3.1 Stiffness. Supporting structures shall be designed to have sufficient rigidity while minimizing local distortions to adequately support the SRB. The mounting structure shall be designed to limit deflection under load to prevent adversely affecting the bearing. The stiffness of the mounting structure should be uniform, and the mounting structure should avoid variances ofstiffness and abrupt changes ofdeflec- tion under the bearing. SRB manufacturers can provide equipment designers and equipment manufacturers with the loaded deflection tolerances required forspecific bearing applications.
5.3.2 Fasteners. The fasteners in an SRB application clamp the joint to prevent relative motion between the mounting surfaces and the bearing. This is accomplished by preloading the fasteners to the point that under the maximum design load, the joint remains clamped. Eitherthroughbolts(orstudswithnutsonbothends) in smooth holes or bolts with tapped holes can be used. Through bolts allow for better control of fastener tension and thereby better load distribution than fasteners used with threaded holes. Whenever possible, use fasteners with a length-to-diameter ratio of 5:1 or greater. It is recommended that hardened flat washers be installed under the heads and nuts of fasteners. The use of lock-spring washers is not recommended.
5.3.3 Fastener Spacing Considerations. Fastener holes shall be spaced so that there is sufficient space between fasteners to allow the use of either a bolt tensioner (preferred) or torque wrench. All fasteners shall be accessible for tensioning or torquing when in service.
5.3.4 Commonly Used Materials. Commonly used materials for SRBs are listed in Nonmandatory Appendix C. This does not preclude the use ofother suitable materials.
6 INSTALLATION This section covers subjects that are normally the responsibility of the equipment manufacturer (or systems integrator, a purchaser of the SRB that installs the bearing in a product either for sale or own use) in conjunction with the SRB manufacturer.
6.1 Mounting Structure and Surfaces SRB manufacturers may provide the pertinent specifi- cations. Before mounting, remove all paint, grease, and other foreign substances from both the structures and the bearing, and check that the surface finish and flatness ofthemountingsurfacesarewithinspecifications.Theuse ofa smoothing stone to remove nicks is common. Shims, grout, or other fillers to flatten the mounting surface shall not be used.