U.S. Department of Labor

Mine Safety and Health Administration 4015 Wilson Boulevard Arlington, Virginia 22203-1984

ISSUE DATE: June 10, 1999

PROGRAM INFORMATION BULLETIN NO. P99-10

FROM:           ROBERT A. ELAM
                      Administrator
                             for Coal Mine Safety and Health

                        MICHAEL J. LAWLESS
                        Acting Director of Technical Support

SUBJECT: Potential Hazard to Roof Bolting Machine
                Operators Due to Inadvertent Control Actuation

Scope
This information bulletin applies to underground coal miners, operators of underground coal mines, manufacturers of roof bolting machines, and Coal Mine Safety and Health (CMS&H) personnel.

Purpose
The purpose of this bulletin is to alert the coal mining industry and CMS&H personnel to a potential hazard to roof bolting machine operators due to the sudden movement of the machine or machine components caused by the inadvertent actuation of machine controls.

Information
The investigation of a recent fatal machinery accident revealed that a potential hazard exists on roof bolting machines with machine controls that are not protected against unintentional activation. This hazard is increased when an operator is at the drill station and, at the same time, controls at other operating stations on the same machine can unintentionally actuate machine functions. Although the recent fatality occurred when an Automated Temporary Roof Support (ATRS) control was inadvertently actuated on a bolting machine retrofitted with a Safe Shield ATRS system, potential hazards exist from other inadvertent control .actuations as well. Likewise, inadvertent control actuations can occur at unattended controls on other bolting machines.

To prevent similar accidents, the following measures should be taken:

• ATRS and other machine controls should be protected from accidental activation that may result in the machine or machine component coming in contact with the operator. Unintentional control activation can be prevented through one or more of the following means:
  
  
  • The controls can be relocated to a protected position.
    
    
  • The controls can be guarded in their existing location.
    
    
  • The hydraulic system can be redesigned to prevent controls at other operating stations from being active while the operator is at the drill station. Diversion valves can be used to divert the hydraulic flow from one operating station to another to prevent controls from being active at more than one operating station.
  
  
  
• Proper storage areas for supplies and materials should be provided on the bolting machine. Care must be taken to avoid placing materials in locations where they could interfere with or fall on machine controls.