Belt drive hardware has rotational
speed limits in order to prevent excessive hoop stress levels that could result
in physical material failures. Material
failures can be catastrophic with fragments thrown outward at high velocities and
energy levels, so speed limits should not be exceeded.
Speed limits are based on the hardware material, as well as
on the hardware configuration. Block
style hardware is inherently stronger than hardware with rims or spokes, so can
operate at higher speeds.
Rotational speed limits are most commonly expressed in terms
of rim speeds. Common units used to
express rim speed are feet per minute (ft/min) and meters per second (m/s). Maximum rpm limits can be calculated from rim
speeds with hardware diameters known. An
equation to calculate hardware rpm from rim speed is as follows:
RPM = (Rim Speed (ft/min) x 3.82)/Diameter (in)
A table from the Mechanical Power Transmission Association
Standard B13i-2013 containing rim speed limits for a variety of hardware
configurations and materials is as follows:
Belt drive hardware is often stamped with maximum rpm values,
and will likely be based on this data.
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