Allied AR110C, Safety, Operation And Maintenance, Page: 19 / 60

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5.0 Sizing the Breaker
The process of selecting the right breaker must
consider the type of work to be done, along with any
special needs such as required modifications when
working in underwater applications.
When sizing the breaker, there are generally three
key points to consider –

Production rate (Type of material to be broken)

Lift capacity of machine

Hydraulic capacity of machine
Obtaining optimal production rates requires efficiency
between the breaker and machine. Other factors
include pairing the right size breaker to match the
material’s hardness and the required degree of
material size reduction.
Materials are fractured by two methods – Penetrative
and Impact. In penetrative breaking, blows from the
piston drive the tool into the material and wedge it
apart. With impact breaking, the blows from the
piston generate compressive stress waves that travel
through the tool and then transferred into the
material, causing it to fracture.
Be careful not to undersize the breaker in hard
material. It is important that the entire impact force
(the stress wave) is transferred into the material. If
not, it will be reflected through the tool and back into
the breaker.
Ideally, it should take 3- 5 seconds to fracture the
material. Anything less than 2 seconds puts the
breaker at risk of idle blows. Running the breaker
continuously beyond 15 seconds will generate
unwanted heat at the tip of the tool.
Using an undersized breaker in very hard material
will negatively impact production as well as
component longevity and reliability. In hard rock
applications, undersized breakers are subjected to
longer running cycles. This generates inefficiencies in
both the machine and breaker. In extreme conditions,
monitoring the condition of wear parts, such as
bushings and tools, will need to be more frequent.
The machine’s service intervals will also require extra
attention.
Production is negatively impacted if the host machine
is too light for the breaker. If the machine is
undersized, the operator will need to work slower to
keep the machine stable. An undersized machine
also limits the amount and size of the material that
can be moved by the machine when raking or
repositioning materials.
Provided the carrier can safely lift the weight of the
breaker, hydraulic comparisons are another key
element for successfully matching the right size
breaker with the carrier. The combination of a
suitably matched hydraulic circuit that is in good
service condition will help to ensure heat generation
and power loss in the hydraulic system is minimal.
It’s important to complete several tests and evaluate
the performance of the hydraulic circuit before the
breaker is used. All hydraulic breakers are designed
to provide optimum performance with reliable service
life at a specific oil pressure and flow range. Before
use, it’s important to review and compare operating
specifications of the breaker with those of the carrier.
The breaker must not be used until testing is
completed and the results confirm the hydraulic
circuit is properly calibrated and set in accordance to
the specifications including oil flow, operating
pressure and back pressure.
Flow requirements and other specifications of the
breaker, including weight, are located in the
Technical Data section of this manual. Tools required
for testing the hydraulic circuit include a flow meter
and pressure gages. An overview of the testing
procedure, along with a form to record the results of
the flow test, can be found in the Technical Data
section in this manual.
Other important considerations include knowing how
your machine is equipped and if any modifications
have been made. Factors such as boom and stick
length, undercarriage and tracks, counterweights,
etc., all affect the lifting capacity of the carrier. Also,
remember to take into account any add-ons such as
a quick attach coupler. Consult the manual provided
by the carrier manufacturer for specifications.
5.2 Auxiliary Circuit and Conversion Kits
Hydraulic work tools, such as Breakers, are not self-
powered. Performance relies upon the host
machine’s ability to provide a suitable hydraulic circuit
that will achieve all requirements specified in the
technical data section of this manual.
Most machines will require some level of conversion
to make use of their hydraulic power. A hydraulic
circuit, capable of producing flow and pressure in one
direction is needed to operate a breaker.