© 2014 Foundation Supportworks
        
        
          ®
        
        
          ,
        
        
          Inc.
        
        
          All Rights Reserved
        
        
          p 47
        
        
          
            Chapter 2
          
        
        
          Helical Foundation Systems
        
        
          
            CHAPTER 2
          
        
        
          HELICAL FOUNDATION SYSTEMS
        
        
          
            2.12.2 Equipment
          
        
        
          
            2.12.2.1 Drive Heads
          
        
        
          FSI currently offers drive heads that range in
        
        
          capacity from 5,000 to 20,000 ft-lb of torque.
        
        
          This range allows for installation of the most
        
        
          common helical products to their maximum
        
        
          torsional ratings. Larger capacity drive heads
        
        
          are available upon request.
        
        
          Proper selection of the drive head should
        
        
          consider the torsional rating of the helical shaft,
        
        
          project installation torque requirements, and the
        
        
          output pressure and flow rate of the hydraulic
        
        
          system to be used. All drive heads have
        
        
          optimum operating specifications that should be
        
        
          partnered with an appropriate hydraulic system
        
        
          to achieve maximum performance in the field.
        
        
          FSI recommends that drive heads have a rated
        
        
          torque output capacity at least 15 percent higher
        
        
          than what is required by project specifications.
        
        
          Hydraulic hoses and fittings should be rated
        
        
          for the operating pressures required and
        
        
          specified by the drive head manufacturer.
        
        
          Hoses and fittings should be checked
        
        
          periodically for damage and replaced when
        
        
          in question. Failure to follow manufacturer’s
        
        
          specifications may result in equipment failure
        
        
          and/or personal injury.
        
        
          Drive heads are generally designed with bail
        
        
          assemblies for mounting to machinery such as
        
        
          skid steers
        
        
          (Figure 2.12.2.1.a)
        
        
          , mini-excavators
        
        
          (Figure 2.12.2.1.b)
        
        
          , backhoes
        
        
          (Figure 2.12.2.1.c)
        
        
          ,
        
        
          and full-size excavators
        
        
          (Figure 2.12.2.1.d)
        
        
          .
        
        
          Smaller, lighter-weight drive heads may also
        
        
          be used with hand-held equipment for interior
        
        
          or limited access installations. Machinery used
        
        
          to power and operate drive heads should have
        
        
          sufficient weight and structural capacity to handle
        
        
          the output torque. A basic rule of thumb has
        
        
          been a pound of machine weight for each ft-lb of
        
        
          torque from the drive head. Although a somewhat
        
        
          conservative rule, machine weight and structural
        
        
          capacity become increasingly more important with
        
        
          greater output torque.
        
        
          Figure 2.12.2.1.a
        
        
          Skid steer
        
        
          Figure 2.12.2.1.b
        
        
          Mini-excavator
        
        
          Figure 2.12.2.1.c
        
        
          Backhoe
        
        
          Figure 2.12.2.1.d
        
        
          Excavator