TM 5-3805-281-24-2
Hydraulic Impact Breaker
33
HIGH BACK-PRESSURE LEVELS
66
Check back pressure reading by removing 1/4 in. gas plug
(A), and attach pressure gauge, with scale setting of 20
bars (290 psi). Run breaker and note pressure level
(gauge will fluctuate; read average). If level is above
recommended level in Technical Specifications, return line
must be modified by one of three following procedures:
1. Re-route return line directly to tank to eliminate any
possible restrictions.
2. Replace oil filter with larger capacity filter (minimum
400 It/min; 60u filtration mesh) or ensure that the
existing filter has been serviced.
3. Increase diameter of return circuit hose or using return
"T" fitting, "T"-off return to a second additional entry
back to tank. (This will increase the effective area of
return circuit and drop back pressure.)
4. If back pressure is still high, call your authorized
dealer.
BREAKER WORKING FREQUENCY
CALIBRATION/REGULATION
NOTE: Prior to undertaking this section, ensure that the
back pressure in the return circuit is at the
breaker specified values.
This section will compare the speed of the breaker versus
its impact power. Speed frequency is controlled by the
spool and spring under the plug (A), also known as the
"Speed Valve". Power is regulated by the spool and spring
under the guiding plug (B), also known as the "Guiding
Valve".
1. Verify the breaker working frequency (speed) by
operating the excavator.
2. Load the breaker perpendicular, choose a compact
block, and set the breaker to a maximum flow
(excavator operating mode and throttle set to
maximum.
Continued on next page
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