|U.S. Department of
Mine Safety and Health Administration|
1100 Wilson Boulevard
Arlington, Virginia 22209-3939
ISSUE DATE: March 29, 2010
PROGRAM INFORMATION BULLETIN NO. P10-03
FROM: LINDA F. ZEILER
Acting Director of Technical Support
KEVIN G. STRICKLIN
Coal Mine Safety and Health
SUBJECT: Use of Automated Temporary Roof Support (ATRS) Outby
Mine operators, roof bolter operators, miners' representatives, Mine Safety and Health Administration (MSHA) enforcement personnel and other interested parties should have this information.
The purpose of this Program Information Bulletin (PIB) is to provide information on the availability of "outby deflector pads", an auxiliary machine-mounted safety device. Outby deflector pads work in conjunction with the ATRS system on certain Fletcher roof bolting machines. The device is intended to reduce roof bolter operator accidents resulting from small pieces of roof rock (roof skin failures) which fall in the area between the ATRS beam and the roof bolters operator's canopy.
This PIB addresses machines manufactured by Fletcher equipped with an "L-style" ATRS beam with a leveling link and articulated beam found on the following models: RR-II, DDO, DDR, CDDR, HDDR, and CHDDR, both with inside and outside boom drilling controls. However, due to potential interference problems, the current designs are limited to mined heights above five feet. For machine-specific retrofit information, mine operators should contact J.H Fletcher personnel.
The outby deflector pads work in conjunction with the roof bolting machine's Automated Temporary Roof Support (ATRS) system. The deflector pads are attached to the outby side of the ATRS and provide additional protection beyond that provided by the drill station canopies.
The deflector should prevent injuries from localized flaking or spalling of the mine roof due to mining conditions and/or geology of the mine.
The outby deflector pad design (shown in Figure 1) typically consists of a fixed center pad or pads, and two outside pads that are hydraulically deployed toward the mine roof from a stowed position. The deflector pads incorporate circular openings (shown in Figure 2) that allow just enough clearance for an 8-inch by 8-inch roof bolt bearing plate to pass through. When deployed, the deflector pads remain approximately two inches from the mine roof, a feature that allows oversized bearing plates, straps, or roof mats to also be used.
FIGURE 1. Plan view of outby deflector pads
FIGURE 2. Hole in the deflector plate
As well as providing additional overhead protection to the bolter operators, the deflectors also help ensure consistent roof bolt spacing since the bolts are installed through the circular openings in the deflectors. Furthermore, since bolter operators don't have to mark bolt locations, they are better able to remain under the drill station canopy.
The outby deflector pads are not part of the certification of the ATRS system, but incorporating them into existing machines will change the part number of the rocker pads, center mount, and beam assembly. Changing of the beam assembly part number will require a new certification tag and letter. A new certification tag and letter will only be issued if the ATRS system has been unmodified and maintained with OEM parts.
Although the outby deflector pads offer significant additional protection to bolter operators, caution must be exercised with their use. Pinch points between the device and the boom arm, mast, drill station canopy, or other machine part may exist. Also, since the device is an auxiliary pad intended to deflect or support small pieces of rock, it does not increase the overall load capacity of the ATRS system. Rather, the outby deflector pads will yield under a large load (approximately 3000 pounds). Also, like the ATRS itself, the outby deflector pads may support loose material that has the potential of striking the operator when the device is lowered. As a result, all personnel should retreat outby to the previous last row of bolts before the ATRS and/or deflector pads are lowered.
Use of this device does not eliminate the need for required examinations or necessary scaling. Visual examinations and sound and vibration tests as required under 30 C.F.R. § 75.211 must still be conducted.
Historically, roof bolter operators have consistently experienced a significant percentage of roof fall injuries, with the majority of these accidents occurring under roof temporarily supported by the bolting machine ATRS system. The area between the ATRS and canopy, and the ATRS and previously installed supports continues to present hazards to roof bolter operators. The outby deflector pads described in this PIB offer an additional measure to mitigate these hazards and should be used whenever possible.
The Federal Mine Safety and Health Act of 1977 as amended, 30 U.S.C. § 801 et seq., 30 C.F.R. § 75.211.
This PIB may be viewed on the internet by accessing MSHA's home page (http://www.msha.gov), choosing "Compliance Info" and "Program Information Bulletins."
Issuing Office and Contact Person(s)
Coal Mine Safety and Health, Division of Safety
Stephen J. Gigliotti, (202) 693-9479
Technical Support, Pittsburgh Safety and Health Technology Center
William J. Gray, (412) 386-6787
MSHA PPM holders
Underground Mine Operators-Coal