Some free-fall hammers, for example, the Menck MHF series and the BSP CX series,
have the option of additional acceleration by pressurizing the ‘equalizing housing’above the
piston, thereby increasing the energy by up to 20%.
The characteristics of various makes of hydraulic hammer are listed in Table 3.2. It is
possible that the driving energy of hydraulic hammers may exceed the rated energy and this
must be considered when analysing stresses during driving (see Section 2.2.6). Generally,
these hammers have the advantage of being able to operate underwater, and because there is
no exhaust they can be operated inside a sound-proofed box. Most modern hydraulic ham-
mers can be fitted with electronic instrumentation giving a continuous display of depth, driving
resistanceand set. The largest APE hammers are equipped with digital radio GRL velocity
sensing and energy monitoring control system.84 Piling equipment and methods
Figure 3.13Driving a 4 m dia monopile foundation for North Hoyle offshore wind farm using a Menck
MHU 500T hammer with large diameter pile sleeve and anvil adapter (courtesy Seacore Ltd).