Investigation of the effects of thrust and hardened washers on the installed tension of a roof bolt

Technical Report · Thu Jan 01 04:00:00 EST 1976

DOI:https://doi.org/10.2172/5780602· OSTI ID:5780602

Sawyer, S. G.; Karabin, G. J.; Debevec, W. J.

The effects of thrust and hardened washers on the installed tension in a roof bolt were studied. Three sets of laboratory tests were run using 30-inch-long bolts with flat, bell, and donut plates, anchored with bail-type expansion shells in a specimen of Indiana limestone by a modified roof-bolting machine. Each type assembly, with and without hardened washers, was randomly installed at a fixed output torque for various levels of applied thrust from zero to 4000 lb. Two salient findings of the investigation were: (1) the application of thrust severely reduced the tension at which the bolts were installed, and (2) the use of hardened washers increased considerably the consistency of the installation of the bolts.

• Research Organization: Mining Enforcement and Safety Administration, Pittsburgh, PA (USA). Pittsburgh Technical Support Center
• OSTI ID: 5780602
• Report Number(s): MESA-IR-1031; ON: DE83902968
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
422000* -- Engineering-- Mining & Underground Engineering-- (1980-)
EQUIPMENT
INSTALLATION
MECHANICAL PROPERTIES
MINING EQUIPMENT
ROOF BOLTS
STRESSES