David K. IngramDavid K. Ingram

Mining Hearing Loss Prevention WorkshopMining Hearing Loss Prevention WorkshopJune 21June 21--22, 200522, 2005

Pittsburgh Research LaboratoryPittsburgh Research Laboratory

Development and Assessment of Controls 

Session

Surface Drill Rigs

Development and Assessment of Controls 

Session

Surface Drill Rigs

Rubber Tire RigsRubber Tire RigsRubber Tire Rigs

Track Mounted RigsTrack Mounted Rigs

Examples: Examples: Air Rotary AAir Rotary A--weighted Sound Levels weighted Sound Levels 

112

92

100

107 106

101

70

75

80

85

90

95

100

105

110

115

120

Hole In-cab Dust Collector Fan Exhaust Compressor

Microphone Location

Soun

d Le

vel d

B(A

)

Engineering Controls forEngineering Controls forTwo Types of Air Rotary RigsTwo Types of Air Rotary Rigs

1) Cab Mounted Rigs 2) Non-Cab Mounted Rigs

What can be done to make the What can be done to make the Cabs Quieter?Cabs Quieter?

• Install sound proofing material

• Replace worn out door or window seals

• Replace broken, cracked or missing glass

• Repair the air conditioner or heater

• Encourage the operator to close the door

• Make sure the cab’s mounting brackets prevent structural vibration

• Isolate the hydraulic control lines from the control panel

How do we isolate How do we isolate hydraulic control valves?hydraulic control valves?

No way!  It’s not 

practical!

(Photo Source: Wilkes & McLean Ltd. internet webpage)

PossibleSolution

Hydraulic Muffler

Solution to Hydraulic Line Solution to Hydraulic Line VibrationVibration

Installed Hydraulic Mufflers:

Idle:91     86 dB(A)

Drilling:98     94 dB(A)

What About Rigs Without What About Rigs Without Cabs?Cabs?

As Designed in AutoCAD

In Use at Drilling SitePartial Cab Partial Cab Design to Design to 

CompletionCompletion

Sound Level Measurements: Partial Cab Engaged Sound Level Measurements: Partial Cab Engaged vsvs DisengagedDisengaged

Disengaged

Engaged

Stop

1/3-Octave Band Center Frequency (Hz)

50

55

60

65

70

75

80

85

90

95

100

A-w

tdSo

und 

Pres

sure

 Lev

el, d

B(A

)

1001251602002503154005006308001000125016002000250031504000500063008000

63 80

Disengaged, 104 dB(A)Engaged, 96 dB(A)

8 dB(A) Reduction with the Partial Cab

Driller’s Comments: Partial CabDriller’s Comments: Partial Cab

•• DesignDesign•• “Looked better than expected”“Looked better than expected”•• UsabilityUsability•• “Cab blocks dirt when setting the surface.” “Cab blocks dirt when setting the surface.” 

The driller said he would have a hard time The driller said he would have a hard time staying/seeing/breathing at the control panel staying/seeing/breathing at the control panel during this process. The cab blocks the dirt during this process. The cab blocks the dirt coming directly at him during the initial drilling coming directly at him during the initial drilling into the surface. into the surface. 

•• Problems with CabProblems with Cab•• Around midday there is glare off the window Around midday there is glare off the window 

panels and he can’t see the drill steel because of panels and he can’t see the drill steel because of the control panel reflection. the control panel reflection. 

Driller’s Comments Driller’s Comments -- Cont.Cont.

•• Cleaning the Partial Cab Window PanelsCleaning the Partial Cab Window Panels•• Used the air line to blow off the dirt from the Used the air line to blow off the dirt from the 

window panels. window panels. •• Changes in rig soundsChanges in rig sounds•• “Can’t hear the drill steel sounds behind the cab. “Can’t hear the drill steel sounds behind the cab. 

Rig sounds different”. We talked about how he Rig sounds different”. We talked about how he would get used to the sound changes, similar to would get used to the sound changes, similar to the changes when wearing the changes when wearing HPDsHPDs. . 

•• Overall thoughtsOverall thoughts•• “I like it.  Other drill operators will want it “I like it.  Other drill operators will want it 

(the partial cab) as well”(the partial cab) as well”

For more informationFor more information

David K. IngramDavid K. Ingram

Phone: 412Phone: 412--386386--6547     Fax: 4126547     Fax: 412--386386--48654865Dai6@cdc.govDai6@cdc.gov

www.cdc.gov/niosh/miningwww.cdc.gov/niosh/mining

Pittsburgh Research LaboratoryPittsburgh Research Laboratory