Carbon Brushes
HERMAN HCB
For commutator motors

HERMAN HCB carbon brushes:
made of a graphite-based composite, the composition of which depends mainly on the current load at the point of contact between the carbon brush and the commutator and on the commutator speed. These are carbon graphite brushes, belonging to the CG (Carbon-Graphite / carbographitic) group according to IEC 60276:2018

Original carbon brushes = balance of opposing requirements:
optimum hardness and composition for their high durability with minimal impact on the wear of the commutator copper blades

Radius of the original carbon brushes:
the pre-prepared radius (roundness) is identical to that of the commutator. At the point of sliding contact, the two friction surfaces - carbon brush and commutator blades - are thus quickly adapted to each other (see table: with / without radius)

Scalloped contact surface of original carbon brushes with radius:
contributes to a better adaptation of the contact surface to the commutator surface, especially in cases where the diameter of a partially worn commutator has been slightly reduced (see table: with / without scalloping)

Shut-off mechanism of original carbon brushes:
when the length of the carbon brush is reduced below the limit specified in the table, the carbon brush is automatically disconnected from the power supply. This protects the commutator from irreversible damage (see table: with / without shut-off mechanism)

Signalling the imminent replacement of the original carbon brushes:
after the service LED indicator lights up, you have about 8 hours to replace the brushes. Prevents unplanned downtime caused by unexpected power interruption (see table: wear indication)

Pair of original carbon brushes:
a complete pair is always supplied (and replaced). In the case of additional functions (e.g. shut-off mechanism), only one of the brushes has this function (the wear of the replaced pair is approximately even)

Lifetime of carbon brushes:
the decisive factors are the maintenance of the engine, its net running time, the number of starts and the load

Warning:
Let's not forget that carbon brushes are both a consumable and the most stressed part of any rotating machine: they must resist friction, elevated temperatures during current passage and be resistant to spark damage. Don't save in the wrong place - a commutator damaged by low-quality (or non-original) brush is often 10 times the expense. When using non-original replacements, the tool warranty cannot be applied