Nook
precision locknuts are designed to provide adjustment, preload and
secure bearings or machine components to shafts and other rotating
machine elements. These locknuts allow accurate setting of preload
on bearings and are capable of supporting axial loads with very
high rigidity without loosening. They also provide very high load
carrying capacities by continuous contact of the thread flanks around
the circumference.
All Nook locknuts provide locking
and loosening prevention within the part itself without the need
of additional components, keys or extra machining. The prevention
against loosening is accomplished in several ways, depending on
the locknut series.
For series MF,
MR, TMF and SFZ, locking is accomplished by using brass radial inserts,
loaded and secured by setscrews. Series MF, MR and TMF have ground
threads and very low axial run-out of 0.002 mm (.00008). SeriesSFZ
have machined threads with axial run-out contained within 0.005
mm (.0002).
For series MKR, locking is accomplished
by axially shifting a portion of the threads. The design provides
increased loosening prevention due to its large contact area. Series
MKR have machined threads with axial run-out contained within 0.005
mm (.0002).
Every Nook locknut is manufactured
with very low axial run-out. This enables accurate assembly and
uniform loading of bearings and other components. The quality of
the threaded contacts provide consistent loading even in repetitive
assembly (tightening) and disassembly (loosening).
In order to maximize the load-ability
of the locknuts the mating thread must be of suitable quality and
strength. The dimension tables show static load ratings (Ca) and
loosening torque based upon thread quality class ISO 6g or better
(4h for high precision applications, such as spindles should be
used) and material strength of 690 N/mm2 (100,000 PSI). The geometrical
tolerances should also be verified. The surface finish of the components
(i.e. thread flanks) should not exceed 0.8 µm Ra (32 µinch).
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