the safety characteristics shall provide correct safe guarding, en-
closing, and insulating features. All moving parts which are of
such nature or so located as to be a hazard to operating or mainten-
ance personnel shall be fully enclosed or guarded. Step surfaces
shall provide a nonskid footing. Nonfunctional sharp edges, projecting
points, and excessive length of fasteners shall be eliminated. An
unobstructed space shall be provided on the rear of the screening unit
for mounting of an emblem identifying slow-moving vehicles. A mounting
bracket socket shall be permanently installed and shall conform to SAE
J725 and ASAE S276. An emblem and its mounting blade shall be furnished
on each screening unit and shall be in accordance with ASAE R276. For
other than travel, the emblem and blade shall be stowed in the toolbox.
3.7 Hoppers and chutes. All portions of hoppers, chutes, plates,
and metal surfaces subjected to abrasive wear caused by aggregate move-
ment shall be lined or faced with replaceable, abrasion-resistant steel
flow of aggregate shall not extend beyond surfaces exposed to the material
and shall be of hardened steel.
3.8 Electrical system.
3.8.1 Electric rotors. The electric motors shall be 1,800-rpm, 440-
volt, 3-phase, 60-cycle, ball-bearing, squirrel-cage-induction, continuous-
rated, totally enclosed, fan cooled, design "C" in accordance with National
Electric Manufacturers Association (NEMA) Standard MG-l, integral horse-
power, class "A" insulation, temperature rise 55 C. Bearings shall be
in accordance with FF-B-171, type as applicable, double-seal class, packed
with grease conforming tO MIL-G-23827.
220.127.116.11 Motor-mounting brackets. All motors shall be provided with
mounting brackets. Where a 5-horsepower (hp) motor is specified here-
in, the-mounting bracket shall also be of sufficient size and provided
with mounting holes to accommodate a 10-hp motor for emergency replace-
3.8.2 controls. All controls, receptacles, and switches shall be
mounted on the screening unit so that they are accessible to the operator
when the operator is standing on the ground.