J&M 220 Operating And Maintenance Manual - page 10
MODEL 220
HYDRAULIC
IMPACT HAMMER
I. GENERAL
INFORMATION
B. MAJOR COMPONENTS (CONTINUED)
Ram
The ram is a one piece high strength steel forging. The one piece construction of
the ram eliminates slack in the driving system and provides maximum energy
transfer to the pile. The one piece construction also eliminates the dangers of
structural failure known to exist in rams constructed of separate segments. High
performance, non-metallic, bearings, retained within the ram, prevent guide column
wear and reduces maintenance and lubrication requirements. The shock and
vibration, generated when the ram impacts the pile, are isolated from the hydraulic
actuator by an elastomeric, self aligning, coupling.
Guide Structure
The guide structure consists of tubular steel guide columns and connection plates.
The guide columns serve to guide the ram and provide the rigidity required to allow
the driving of batter piles. Guide columns, connecting plates and lifting bale are
held together by tensioned wire ropes which run from the base plate to the top of
the lifting bale. These cables provide a resilient means of connection and eliminate
the need for keys or bolted connections. The hammer is designed to fit in 26” x 8”
rail leads produced by J&M and other manufacturers. The connecting plates
provide mounting points for the lead guide rails necessary for J&M leads and
various other hammer guidance systems.
Lifting Bale
The lifting bale surrounds and protects the hydraulic actuator and hoses from
damage and is the attachment point for the lifting sheave. Two energy storing
hydraulic accumulators are mounted to, and protected by, the lifting bale.
Incorporated in the lifting bale design are the connection flanges for the hydraulic
supply hoses, and a shock absorbing hose support.
Drive Cap Assembly
Striking energy of the ram is transmitted to the pile through the three elements of the
drive cap assembly. The ram impacts the forged steel striker block which self aligns
and self centers within the lower connecting plate. Ram energy is transferred
through cushion material into the DCB-X drive cap base. The DCB-X serves to
retain the cushion material, Guide the piling, and adapt to various styles of J&M
piling inserts. Piling inserts adapt the hammer to most popular types of piling and
retain additional cushion material when required.
I-2