Dozer Engulfment Case Study

Jack KatlicSr VP-Fuel Supply, AEP- Retired

Mark SkilesDirector of Technical Support, MSHA

Phil SouthernBodygard

Sunnie SouthernBodygard

Dozer Engulfment Case Study

• Agenda– Surge Pile Hazards

– Surge Pile Accidents

– Solutions for Stronger Cab Windows

– Demonstration

– Conclusion

– Panel Discussion

Dozer Engulfment Case Study

• Purpose– Share one method the coal industry has implemented to save lives

Surge Pile Hazards

Surge Pile Safety

Directorate of Technical Support Mine Safety and Health Administration

Slides with the MSHA logo were adapted from the MSHA website and can be found at: www.msha.gov

Surge Pile Hazards

• Feeding material acts like “quicksand”

Surge Pile Hazards

• The edge of the drawhole is unstable

Surge Pile Hazards

• Poor visibility

Surge Pile Hazards

• Since 1980, 19 persons have died in coal mining related surge pile accidents

• Most of the accidents have involved a hidden cavity created when material “bridged” over a feeder

Causes of “Bridging” Over a Surge Pile Feeder

• Bridging can occur– When equipment transverses

the material at the surface of the pile

– Surface material compacts creating a false roadway

– “Settling in” may occur in an idle pile and increase risk

Surge Pile Accidents

Note the thickness of the material that had been bridged over

Dozer Buried in Cavity

A hidden cavity collapsed under the dozer while it was pushing coal on the pile

Partially Buried Bulldozer in Fatal Accident in Pennsylvania

• Most fatal accidents occurred when the dozer cab windows either broke, or were pushed into the cab, allowing coal to fill the cab

Cab Filled with Coal

The coal has broken or pushed in the cab windows and filled the cab

Note: orange object under windshield is an self contained self rescuer (SCSR)

Windshield pushed back into cab

Best Practices: Ways to Improve Surge Pile Safety

Best Practices: Surge Pile Safety

• Provide equipment cabs strong enough to resist burial pressures

Solutions for Stronger Cab Windows

Available Solutions for Stronger Cab Windows

• MSHA initiative– Use of very high-strength glass

• Massey approach– Add supports to the inside of the cab windows - combined with using

somewhat stronger glass

• Use of polycarbonate windows – Adequate strength– Support around edges needs to allow for higher deflection – Issue of scratch-resistance

• Bodygard system– A customized polycarbonate system

Massey Subkit

Massey Subkit

• The first system

• Most widely used

• Effective in saving lives

• System design– is comprised of metal bars attached to the inside of the cab

– keep the cab and glass from collapsing on the operator

The Massey Approach

•Installed support bars on the inside of the cab windows

•The supports for the right-side door window are shown here

•Horizontal support bars and additional edge support for the windshield are shown here

The Massey Approach

•Massey’s successful burial demonstration

•The glass cracked but it held the coal out of the cab

The Massey Approach

Contrast this scene after the Massey demonstration - where coal was held out of the cab - with...

This scene from an accident, where coal has filled the cab...

Massey Subkit

• Advantages– Keeps cabs from

collapsing

– Least expensive

– Saves lives

• Disadvantages– Obscures vision especially

when backing up

– Causes cycildelic affects that result in complaints of headache from operators

– Metal bars rattle and increase noise level in the cabin

– Metal bars loosen and crack door glass that must be replaced

PPG Preformed Pre-designed Product

PPG Preformed Pre-designed Product

• Created as by request of MSHA to overcome the deficiencies of the subkit

• System design– A chemically hardened preformed pre-designed product

– Installed by gluing the glass into a gasket is installed in same manor as standard glass packages

High-strength glass installed using urethane adhesive

Field Burial Demonstration

Federal No. 2 Mine

Near Morgantown, WV

High-strength glass installed in all cab windows of test dozer

Dozer with high-strength glass being buried in coal pile

Buried dozer being dug out

Checking windows after burial

High-strength glass intact after burial demonstration

PPG

• Advantages– Does not obstruct vision

– Resists static pressure up to 40 psi

• Disadvantages– Preformed therefore

application is limited to Caterpillar and Komatsu dozer’s* standard cab packages

– Requires fixing of any deformation of the cab prior installation of the glass

– Most expensive

– May crack when impacted

– May pop-out under stress

PPG Preformed Pre-designed Product

Pounds per square inch

*Molds are only for dozers not for end loaders

Bodygard System

Bodygard System

• Custom engineered

• Custom installed

• Polycarbonate system– Outboard seat is created

– Material is mechanically attach to the cab

• Inhibits internal collapse

• Unbreakable

• Noise insulator

• On site installation

• All manufacturers

• MSHA approved

Case Study History

• Massey conducted drop tests of 3 systems to determine the most effective system

• The following demonstration shows the results of the test

Dozer Drop Test Demonstration

Body Guard

• Advantages– Unbreakable

– Does not obstruct vision

– Can be made to fit anything (all makes and models of existing equipment)

– Absorbs and insulates sound

– Broad based system

– Onsite customized installation on all cabs

– Installed on site by drilling and attaching to cab

– Cut to specs and attached to ensure stability

• Disadvantage*– Is less scratch resistant that

regular glass therefore a protective covering is applied that is easy and inexpensive to replace

Bodygard System

*Protective replicable material is applied to improve the scratch

resistance

Conclusion

• Based on the results of the drop test, Massey signed a national contract with Bodygard to perform their installations

BODYGARD

1 Lincoln Center, Shinnston, WV 26431

“The Safety Window People”

www.bodygard.com 304-592-1980