NIOSH has developed a collapsible drill steel enclosure (CDSE) to encapsulate the drill steel of a roof bolter during the drilling portion of the roof bolting machine duty cycle. Underground field tests have demonstrated that it can reduce time-weighted noise exposure from roof bolting machine drilling noise by up to 7 dB. In addition, NIOSH is collaborating with J. H. Fletcher & Co. in the continued development of a CDSE.

Design features of the CDSE include:

• Reduce operator noise exposure by up to 7 dB
• Allows operator to see drill steel to line up holes and monitor steel bowing
• Easy to use design
• Retrofits easily to any roof bolting machine
• Collapses as drillhead nears the roof
• Swings out of the way to allow for normal roof bolt installation

Additional information:

• Complete part specifications and blueprints
• Video Demonstration of CDSE

For more information about the collapsible drill steel enclosure, contact NIOSH Mining at PitHealth@cdc.gov.

Example of sound pressure level reduction using the CDSE

Noise sources when drilling without CDSE.	Noise sources when drilling with CDSE and a 56 cm gap.	Noise sources when drilling with CDSE and a 30 cm gap.	Noise sources when drilling with CDSE and a 15 cm gap.

Related Documents:

• A Noise Control for A Roof Bolting Machine: Collapsible Drill Steel Enclosure (PDF, 459 KB, 2008)
• Technology News 532 - Collapsible Drill Steel Enclosure for Reducing Roof Bolting Machine Drilling Noise (PDF, 318 KB, 2008-09)