(a) Gears, sprockets, friction devices, and couplings with protruding bolts or nuts, shafting and projecting shaft ends that are within seven feet of floor or platform level, belt or rope drives that are within seven feet of floor or platform level, fly wheels, and circular and band saws, and planers shall be guarded adequately.
(b) Grinders shall be installed and maintained in such manner that wheel speeds will not exceed rated speeds and reasonable protection is afforded against danger of flying particles and wheel disintegration.
(c) Repair pits shall be kept covered or guarded at all times when not in use to prevent falls into them.
(d) Machinery must be stopped before being lubricated, wiped, or repaired and reasonable precautions must be taken to prevent other persons from restarting them while such work is in progress. This does not apply as to lubrication of machinery that is designed or modified so that lubrication may be performed without exposure to danger from moving parts.