J&M 220 Operating And Maintenance Manual - page 29

MODEL 220 

HYDRAULIC 

IMPACT HAMMER 

III. OPERATING 

INSTRUCTIONS 

E.  OPERATION OF THE HAMMER 

The Model 220 hydraulic hammer is a free-fall type hammer.  The ram is lifted by 

the hydraulic cylinder and then allowed to free-fall. 

1.  Rated Hammer Energy 

Rated hammer energy of 88,000 ft-lbs (119 kj) is achieved at an operating 

stroke of 4'-0"(1.2 m).  Minimum operating energy of 11,500 ft-lbs (15 kN-m) 

occurs at an operating stroke of 1'(.3 m).  The energy at which the hammer is 

operating may be determined by measuring the operating stroke, in feet (m), 

and multiplying the stroke by the weight of the ram 22000 lbs (9978 kg)to get 

energy in ft-lbs (kN-m).  Stroke length may be measured by observing the 

stroke length scale (decal) located on the guide angles, and comparing them to 

the pointer on the ram.  The stroke length scale is marked in 1/4 ft (.076m) 

increments. 

2.  Maximum blows per inch 

Driving in excess of 10 blows per inch(25.4mm) is considered practical refusal.  

Driving in excess of 10 blow per inch  is considered improper use and will void 

the hammer warranty. 

3. Stroke 

Control 

Stroke of the Model 220 hammer is controlled hydraulically via the location of 

the trip valve lever.  The hammer may be operated at infinitely variable stroke 

length within the 4’-0”(1.2 m) to 1’(.3m) limits.  The full stroke setting is the 

normal operating mode for the hammer.  The reduced stroke setting is engaged 

via the control panel. 

III-4