Figure 12-7.Limit of approach for power lines.

Equipment Operator Basic - Beginning construction equipment operators manual
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Truck cranes have a high ground bearing pressure, ranging from 75 to 100 psi due to the pneumatic tires on which the machine travels. On a firm, dry surface, a truck carrier can climb a 40-percent grade. Depending on the design of the carrier, the turning radius can range from 50 to over 90 feet. This high turning radius limits its maneuverability. Before any crane travels to a jobsite, the crane crew supervisor must visually review the planned travel route to determine if low wires, low overpasses, narrow bridges, or other unsafe obstacles exist. The absolute limit of approach for power lines (fig. 12-7) is the following: 1. 0 to 125,000 volts, 10 feet 2. 125,000 to 250,000 volts, 15 feet 3. Over 250,000 volts, 25 feet Anytime you are traveling with a crane, stay a minimum of 4 feet from any electrical power source. When traveling with a truck-mounted crane equipped with a lattice boom, do NOT rest the boom on the cradle, as the lower cords of the boom can be dented if the boom bounces while traveling. Position the boom 2 to 4 inches above the cradle. Truck- and wheel-mounted cranes are rated at 85 percent of the minimum weight that can cause the crane to tip at a specified radius with the basic boom. The truck carrier is equipped with outriggers that provide more stability for the crane; therefore, when you are making crane lifts, the outriggers should always be used. As outlined in the COMSECOND/COM- THIRDNCBINST 11200.1, Naval Mobile Construction Figure 12-7.—Limit of approach for power lines. Figure 12-8.—Truck-mounted crane quadrants of operation. I 12-4

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