Impact Hammer - Direct Drive System Operation (Refer To Figure K-10.)
The direct drive system transfers the impact energy developed by the piston and impact block in the
lower cylinder to the pile being driven. This is provided by the direct drive assembly connected to the
bottom of the lower cylinder that houses the recoil dampening system and striker plate (driving head).
During operation of the impact hammer the following sequence takes place.
At the bottom of the piston downstroke, the nose of the piston strikes the top of the
impact block in the lower cylinder.
The impact block moves unimpeded and strikes the top of the striker plate in the direct
drive assembly, transferring the impact energy from the impact block to the striker plate.
The impact energy from the striker plate is then delivered to the pile being driven by the
striker plate. The striker plate evenly distributes and transfers the impact energy to the
pile head to minimize mushrooming/splitting of the piling.
The pile is driven into the soil.
The recoil dampening system, consisting of the six cushion rings and cushion
compression ring in the direct drive assembly, dissipates the rebound energy to allow up
to 95% of the impact energy to be transmitted to the pile and only 5% of the rebound
energy back to the impact hammer.