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| Shafting |
- a
primary cause of premature pulley failure is extreme shaft
deflection
- proper shaft sizing is very
important as it directly affects all other components in the
assembly
- high strength shaft materials
better accommodate torsion and fatigue cycles
- NOTE: higher strength
alloys do not increase the beam strength of a shaft
- RASP shaft selection is
based on deflection in bending without consideration of
constraints
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Standard Shafting |
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- typically machined from AISI C1045,
C4140
and C4340 steel
- machined to precise sizes with large radii and finished
journals
- this combination
of high-grade steel with a high quality finish minimizes stress concentrations and ensures
adequate shaft strength
- design angle of slope at the pulley
hub is generally limited to 0.15% (0.0015 radians) for shafts
in low-tension idler pulleys and all shafts in lower tension systems
(where belt tension does not exceed approx. 15,000 lbf).
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Engineered Class Shafting |
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-
RASP
"Mine Duty" shafts are
typically machined from blanks of AISI C4140 or C4340 steel
-
standard surface
finish is 250 RMS micro-inches, 125 RMS micro-inches below the
locking device and 63 RMS micro-inches on all radii and journals
-
this combination
of high-grade steel with a high quality finish ensures shaft
strength and eliminates stress concentrations
-
the design angle
of slope at the pulley hub is generally limited to 0.1%
(0.0010 radians) for drive and high-tension pulley shafts
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