TM 5-3805-281-24-2
Hydraulic Impact Breaker
33
If frequency (speed) is too low, adjust as follows:
68
1. Check that oil flow is correct.
2. Using a hexagonal wrench (see Torque Specifications),
disassemble "Speed Valve" (Plug). The purpose of this
is to regulate hammer blow rate according to working
conditions.
3. To increase working frequency, add adjustment shims
under spring. Each shim added will increase frequency
by about 2%. Maximum allowed number of shims is
eight (usually adding 1--5 will do). Before adding any
shims, check with your authorized dealer that there is
not an easier solution. Adding adjustment shims
causes the breaker to decrease its power but increase
its speed. By varying the opening pressure of the
"Speed Valve" according to the number of shims.
However, most breakers with maximum specification
flow will not need shim adjustments.
4. Replace plug "Speed Valve" onto head and tighten
firmly.
If the frequency is too high, follow the above steps, in
removing the adjustment shims instead of adding them.
Removing adjustment shims causes the breaker to
increase its power and reduce its speed. Alternatively, if
the frequency is too high, verify that the flow from the
carrier is not too high (in excess of hammer
specifications).
EXCESSIVE WORKING FREQUENCY - FURTHER
ADJUSTMENTS
If, after the shim adjustment, the working frequency is still
too high, check that the needle/piston (2) is sliding easily
inside the valve body (1). If the problem persists, increase
the working pressure (add 2 shims to the power valve) by
approximately 10 bars (145 psi). The spring rigidity is
directly proportional to the hardness of the material, and
so will affect the blow frequency. If operating on soft
material, and the breaker speed is still too high, the
"Power Valve" may have to be adjusted, as well as the
"Speed Valve" (8). Refer to the following procedures.
CED,OUOE039,5
1920MAR999/9
20-64
