Even though the maximum
allowable thrust load capacities for retaining rings are given in the manufacturer's
technical manual, there are numerous design applications issues to consider.
For example, if a ring is seated in a groove cut in material softer than the
ring, the thrust load capacity of the groove becomes the limiting factor in the
assembly. If a ring is installed in a housing or on a shaft made of hardened
steel, however, the maximum allowable static thrust load capacity listed in the
manufacturer's technical manual may be used.
is thrust load capacity for your design? If you plan to use rings to position
and secure bearings in a pump, or lock up components in a car or truck
transmission, load capacity can be critically important for function, safety
and reliability of the ring application. On the other hand, if you plan to use
a ring merely to hold a plastic name plate in place on a piece of equipment,
you likely will not have to worry about loads on the ring. All you need is a
ring that will stay put once you have it positioned. It is pointless to over
design for high load capacity and pay the price for rings and grooves when
another ring will do the job for less.
For example, consider an
assembly in which you have to fasten components in a bore or housing .750"
(19.0mm) in diameter. A self-locking retaining ring, which does not need a
groove, provides 66 lbs. of static thrust load capacity; an external retaining
ring for the same application installed in a soft groove provides 1,200 lbs. of
static load capacity with a safety factor of 2. If the load capacity of your
application is 66 lbs. or less, then the self-locking ring presents the most
economical and effective approach to meeting this fastener requirement.
The bottom line here is that paying
close attention to load capacity requirements before making any ring selections
can save costs in this stage of your design.Ring Thrust Loads
For maximum thrust capacity in both static and dynamic loading, the
abutting face of the retained part should have a square corner. Fit of the
retained part in the housing or on a shaft should allow reasonably concentric
uniform loading against the ring.
there is radial play between the retained part and the shaft or housing, such
play must be treated as though the retained part had a chamfered corner. The
magnitude of the chamfer should be considered equal to the play. Therefore, loading
data for rings abutted by chamfered parts as shown in the specific manufacturer's
ring data charts must be considered.
load capacities for rings apply only to standard thickness rings made of
standard materials using the shear strength values listed in Table 1.
When the special materials listed in Table 2 are used, multiply the
allowable thrust load of the ring by the conversion factor shown.
Groove Thrust Loads
The allowable thrust loads listed for rings used in grooves are based
upon a housing or shaft material of cold rolled steel with a tensile yield
strength of 45,000 psi. In the case of beveled retaining rings, the values
given in Table 3 are for minimum contact between ring and groove-i.e.,
engagement of the beveled edge of the ring with the beveled groove wall at a
length equal to half of the groove depth (d/2).
the following materials are used, multiply the allowable thrust load of the
groove by the conversion factor shown in Table 3.