MS3216D
9. Recommended design limitations and usage.
(a) Intended use - To provide large shoulders for positioning and maintaining machine parts. They are applied radially and are locked positively in their groove by means of two prongs extending from the inner circumference to the open end. They withstand high thrust loads and relative rotation between the retained parts. Their bowed construction provides resilient end-play take-up in axial direction. They may be assembled and disassembled with a screwdriver or with the prong-lock applicator. Sizes .125 to .312 are available rod-stacked for high speed application. The use of the following formulas are based on the fact that the ring material will not fail in compression. Limitation on use - the following formulas are not to be used for brittle materials such as cast iron, etc.
Warning - Rings shall not be over expanded during installation since this will lead to ring failure. (b) Allowable thrust load capacity of the rings. Abutting components to have sharp corners =
STX P = 1.75 F
P = Allowable thrust load (pounds). S = Shaft diameter (inches).
Where: T = Ring thickness (inches).
X = Ultimate shear strength of the ring material (psi). 1/ F = Factor of safety.
A safety factor, F = 3, is recommended, since the ring after flattening under load is subjected not only to pure shear stresses but also to bending stresses.
(c) Allowable load capacity of groove wall =
P = SdY
2F
P = Allowable compression load (pounds) S = Shaft diameter (inches)
Where: d = Groove depth (inches)
Y = Yield strength in compression of the groove material (psi) F = Factor of safety
To insure a safe working load a safety factor, F = 3, is recommended, since the working stress in the groove section is raised considerably by the notch effect of the deep groove.
(d) Minimum distance between outer groove wall and end of shaft =
Z = Minimum distance between outer groove wall and end of
Z = 2d Where: shaft (inches)
d = Groove depth (inches) (e) Differential rotation =
Differential rotation of ring and adjacent part creates no element of risk, because the ring is locked in its groove by two locking prongs.
1/ X = 130,000 psi ultimate shear strength for rings of carbon steel or corrosion resistant steel.
X = 110,000 psi ultimate shear strength for rings of beryllium copper.
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