New product announcements: 12/02/2009 Rotary Hammers: Anti-Vibration System The new line of DeWALT heavy-duty SDS Rotary Hammers feature the SHOCKS Active Vibration-Control system, which reduces vibration by up to 50%. The 1-in. SDS hammers are capable of up to 4,300 bpm, with a large hammering mechanism that generates 2.5 ft-lb of impact energy. The D25323K and D25324K hammers are compatible with the DeWALT D25300DH dust-extraction system with HEPA filter. A quick-change keyless chuck system is available on the D25324K. DeWALT Power Tools; 800-433-9258; www.dewalt.com Grading System: Upgraded for Reduced Error The upgraded AccuGrade laser-based grading system for Caterpillar’s C-Series Skid-Steer
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.