Tuesday, April 26, 2016

Using Extra Wide Driven Sprockets and Sheaves to Increase Bore Ranges

Hardware component selections for normal belt drives use the same widths for both the driver and driven sprockets or sheaves.   This looks normal and works well most of the time.

But what if the driven shaft diameter is unusually large and exceeds the bore range of the selected driven sprocket or sheave?  One option is to re-design and select hardware components with larger bore ranges.  Another option is to consider using a driven component in the same diameter, but in a wider width than necessary.

For example, an 8MX-140S-12 sprocket uses a 2012 bushing with a maximum bore of 2.125”.  An 8MX-140S-21 sprocket uses a 2517 bushing with a maximum bore of 2.688”.  In this case, just using a sprocket with a 21mm face width instead of a 12mm face width will increase the sprocket bore range from 2.125” to 2.688”, which is considerable.  This principle can apply to other sprocket, pulley and sheave types as well.

With synchronous belt drives there is no harm in using wider driven sprockets so long as the driver sprocket is double flanged so the belt is constrained appropriately on both sides.  A wider driven sprocket may look unusual, but will function just fine.  And the parallel sprocket alignment isn’t as critical with the wider sprocket face width.

With V-belt drives there is no harm in using wider driven sheaves.  There may be some empty sheave grooves in the wider driven sheave, but this will not pose any problems.  Just be sure to accurately align the driver sheave grooves with the driven sheave grooves that will contain V-belts.

For questions or further information, contact Gates Product Application Engineering at 303-744-5800 or at ptpasupport@gates.com

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