KENT Nordco KF3BM, Owner'S Manual

Page: 9 / 36

NOV/2005 Section A – Page #5
PRINCIPLE OF OPERATION
The impact energy is a product of the force acting on piston and the length of its stroke. The
piston is powered by the direct action of the hydraulic oil pressure and flow to the hammer.
The following illustration is a simplified sketch of the hydraulic oil porting of the hammer. Area
(A1) of the piston is larger than area (A2) of the piston. Area (A1) is alternately connected to the
pressure (IN) or the return (OUT) lines of the hammer by the valve. Area (A2) is always connected
to the pressure (IN) line. Area (A3) is an unpressurized chamber which allows for the free
movement of the piston.
The piston rises when area (A1) is
connected to the return (OUT) line. The oil
pressure on area (A2) is greater than the
oil pressure acting on area [A1], driving the
piston upward.
At the end of the return stroke, the
valve shifts, diverting the oil to area (A1) of
the piston. The oil pressure drives the
piston downward striking the working steel.
The kinetic energy of the piston at this
point is transferred to the working steel.
The working steel is then driven into the
material to be broken. At this point, the
valve shifts back to its original position,
causing the cycle to repeat.
To maintain continuous oil flow during
the valve shift, a bladder-type accumulator
is utilized. The accumulator acts as a
variable size reservoir for the oil, allowing
for continuous oil flow during the time the
piston is changing direction. This reduces
the pulsations in the hydraulic system.