OPERATOR’S MANUAL
9
3. TECHNICAL DESCRIPTION JUNTTAN HAMMER
JUNTTAN hammer is a hydraulically-powered drop hammer for impact driving.
The cage frame houses the components of the hammer. There are bolted wear
pads on each corner of the ram block which slide along inside the frame
uprights. There is a hole inside the ram block. The ram block is bolted together
with a top plate. There is a rubber plate between the top plate and the ram block
to reduce the effect of the return stress wave during driving. A shaft connects
the top plate to the piston rod of the lifting cylinder through the lifting eye. The
spool valve which controls the lifting cylinder is built into the top end of the
cylinder. The spool valve is operated by a solenoid pilot valve. The position of
the piston rod is sensed with an inductive proximity switch. The lift buffer on the
top plate limits the stroke of the lifting ram during lift. For pile driving the
hammer is placed on the top of the pile. The hammer frame goes down until the
drive cap inside the drive cap housing moves against the rebound ring. In that
position the drive cap is at the end of its stroke and the ram block rests on
cushion.
The main components of the hammer are:
1. frame
2. modular ram block
3. lifting cylinder
4. top plate
5. ram block bolts
6. solenoid valve
7. hydraulic accumulator on the
pressure side for storing energy
8. hydraulic accumulator on the return
side to even pressure surges
9. proximity switch
10. drive cap housing incl. drive cap,
cushion and rebound ring
11. leader guides
12. ram block lifting eye
13. spool valve
14. frame extension
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