Stress Analysis RPM Capacity Load Capacity Introduction

Ring Design

 

The maximum recommended RPM for all standard external Smalley Retaining Rings are listed within our tables of standard rings .

 

A Smalley Retaining Ring, operating on a rotating shaft, can be limited by centrifugal forces. Failure may occur when these centrifugal forces are great enough to lift the ring from the groove. The formula calculates the RPM at which the force holding the ring tight on the groove (cling) becomes zero.

 

Rapid acceleration of the assembly may cause failure of the retaining ring. If this is a potential problem, contact Smalley engineering for design assistance.

 

N	1	2	3	4
Y	1.909	3.407	4.958	6.520

Nomenclature

N = Maximum allowable RPM
E = Modulus of elasticity (psi)
I = Moment of inertia = [(t b³)/12] (in⁴)
g = Gravitational acceleration = 386.4 (in/sec2)
V = Cling/2 = [(D_G - D_I)/2](in)
D_G = Groove diameter (in)
D_I = Free inside diameter (in)
Y = Multiple turn factor (right)
n = Number of turns
γ = Material density = .283 (lb/in³)
A = Cross sectional area = (t b) - (.12)t² (in²)
t = Material thickness (in)
b = Radial wall (in)
R_M = Mean free radius [(D_I + b)/2] (in)

 

Self-Locking

 

This feature allows the ring to function properly at speeds that exceed the recommended rotational capacity. The self-locking option can be incorporated for both external and internal rings. The self-locking feature utilizes a small tab on the inside turn “locking” into a slot on the outside turn. Self-locking allows the ring to operate at high speeds, withstand vibration, function under rapid acceleration and absorb a degree of impact loading.

 

Balanced

 

Smalley’s balanced feature statically balances the retaining ring. A series of slots, opposite the gap end, account for the missing material in the gap. This characteristic is very useful when the balance of the assembly is critical and it is necessary to reduce eccentric loading.