ISSUE DATE: 4/13/2011

PROGRAM INFORMATION BULLETIN NO. P11-24

FROM: LINDA F. ZEILER 

 Acting Director of Technical Support 

 KEVIN G. STRICKLIN 

 Administrator for 

 Coal Mine Safety and Health 

 NEAL H. MERRIFIELD 

 Administrator for 

 Metal and Nonmetal Mine Safety and Health 

SUBJECT: Re-Issue of P09-35 - Continuous Mining Machine Safety

 Features (Main Machine Circuit-Interrupting Device, Remote

 Traction Motor Circuit Breaker Reset, E-stop Override, Methane

 Monitor Failure Override) 

Who needs this information?

Operators of underground coal or metal and nonmetal mines, independent contractors, 

miners’ representatives, Mine Safety and Health Administration (MSHA) enforcement 

personnel, state mining agencies, mine equipment manufacturers, and other interested 

parties need this information. 

What is the purpose of this bulletin?

This bulletin is intended to inform the mining industry of certain features that provide 

safe measures when operating certain continuous mining machines with hand-held 

remote controls during extended cut operations. Some continuous mining machines 

have been designed with safety design features that could help reduce the number of 

accidents from the use of the equipment during extended cut operations. This bulletin 

informs the industry of the following features: 
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(1) Main Machine Circuit-Interrupting Device 

(2) Remote Traction Motor Circuit Breaker Reset

(3) Emergency Stop Override

(4) Methane Monitor Failure Override

What is the capability of these features?

The Main Machine Circuit-Interrupting Disconnect Device is approved for certain 

models of continuous mining machines. The purpose of this switching device is to 

reduce the hazards associated with main machine breaker trips on the continuous miner 

when the machine is under unsupported roof. This feature will allow the breaker to be 

reset at the power center and negate the need for the continuous miner operator to 

manually reset the main breaker on the machine itself. 

The Remote Traction Circuit Breaker Reset is also approved for certain models of 

continuous mining machines. The purpose of the remote traction reset feature is to 

provide a safe method of resetting a tripped traction circuit breaker when the machine 

is under unsupported roof. The breaker handle is operated mechanically by a hydraulic 

cylinder located in the enclosure on the machine. The cylinder is activated by 

energizing solenoids from the portable hand carried remote control. Once reenergized, 

the machine can then be trammed to supported roof areas. 

The Emergency Stop Override feature is approved on certain models of continuous 

mining machines. When the emergency stop switch located onboard the machine has 

been accidentally engaged by the action of the machine against the rib, this feature 

allows the operator to move the machine to a supported roof area to manually reset the 

emergency stop switch. 

The Methane Monitor Failure Override is approved on certain models of continuous 

mining machines. When the machine's circuitry detects a methane monitor system 

malfunction, the machine will automatically shut down and the operator will be 

informed of the malfunction. The continuous mining machine operator then has the 

option of tramming the machine back to supported roof for repair. When engaged, the 

override feature automatically disables certain machine functions (i.e. cutting or 

conveying). The override feature will not work when the machine de-energizes due to 

high methane concentrations and the machine's circuitry will not allow the machine to 

be trammed back to supported roof until the methane concentrations are reduced. 

It should be noted that, if the override feature is used to tram the machine back to 

supported roof, methane testing using other methods must continue in underground 

coal mines in order to detect hazardous concentrations of methane while tramming as 

prescribed by Title 30 Code of Federal Regulations (C.F.R.) 75.362(d)(1)(ii) and (iii) for 

underground coal mines. With respect to I-A, II-A, III, and V-A metal/nonmetal mines, 

in order to avoid a citation for not having an operable methane monitor system, it is 
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recommended that methane monitoring using other methods continue while tramming. 

If high methane concentrations are detected, the machine will shut down as required by 

30 CFR 75.342, 57.22306, 57.22307, 57.22308, and 57.22309. 

What is the background for this bulletin? 

Continuous mining machines operated by hand-held remote controls are being used to 

make extended face cuts. The machine, at times, is completely under unsupported roof. 

If the tram breaker trips or the methane monitor malfunctions, the machine is disabled, 

requiring the breaker to be reset or repairs made to the monitor system at the machine 

location. If the machine is beyond supported roof, temporary roof supports are 

required in the unsupported areas in order for workers to access the machine and reset 

the breaker or repair the monitor. 

At least one manufacturer has these features available for certain continuous mining 

machines. The features are engineered such that the disabled machine can be safely 

trammed from unsupported roof areas so the methane monitor system can be repaired 

and other functions such as cutting or conveying circuits can be re-energized. 

What is MSHA's authority for this Program Information Bulletin?

The Federal Mine Safety and Health Act of 1977; 30 C.F.R. Parts 57.22306, 57.22307, 

57.22309, and 75.342. 

Is this Program Information Bulletin on the Internet?

This PIB may be viewed on the Internet by accessing the MSHA home page at 

(http://www.msha.gov) and choosing "Compliance Info" and "Program Information 

Bulletins." 

Who is the MSHA contact person for this bulletin?

Technical Support, Approval and Certification Center

Kenneth J. Porter, (304) 547-2030

E-mail: porter.kenneth@dol.gov

Coal Mine Safety and Health, Safety Division 

John Arrington, (202) 693-9549

E-mail: arrington.john@dol.gov

Metal and Nonmetal Mine Safety and Health

Safety and Health Division

Marvin Lichtenfels, (202) 693-9600

E-mail: lichtenfels.marvin@dol.gov

Who will receive this bulletin?

MSHA Program Policy Manual Holders
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Underground Mine Operators

Mine Equipment Manufacturers

Miners' Representatives

Special Interest Groups