Festool C12 EC-TEC Review Manual page 3

asked of it, the drill will shut down to prote
battery.
This is an important feature that might be
misunderstood by many users. Even though the
drill seems to have plenty of power for a moderat
load, if you try to take a heavy l
battery, it will shut down the motor to protect the
battery. Other d rills will allow you to over-draw
the battery and shorten its life.
Gearbox
The C12 gearbox is virtually bulletproof. To
harness the power of the motor, the C12 uses a 3-
stage planetary geartrain. This is the same type of
gear set used in automotive transmissions for it
strength and versatility.
In a planetary drive,
the power of the motor is shared by dozens of ge
teeth instead of just a couple. It also permits for a
very high gear ratio in a small amount of space.
This type of geartrain allows the motor to spi
very high RPM, and produce very high torque
levels at the output shaft via gear reduction.
Switching between high-speed and low-speed
gears, simply disables or enables the mid-stage
planetary gear set.
Electromechanical C
and Motor Cut-Out
For driving screws, the C12 has a 24-position
torque clutch selector. This allows you to
determine at what power level the drill stops
turning to prevent breaking or stripping screws.
This is nothing new, as most drills have a slip-
ct the clutch for this purpose. What is new is how
Festool has implemented a motor cut-out feature
into the slip clutch.
If you are anything like me, the grinding sound of
e a slipping torque clutch is like fingernails on a
oad from a low blackboard. I hate that sound so much that I refuse
to use the torque cut-out feature on a drill. Much
to my elation, Festool has found a unique way to
ease my pain.
The slip clutch on the C12 will slip only half a
revolution before the motor detects the slippage
and shuts down. No more do I have to put up with
the endless grinding sound from the slip clutch.
For reliability, the C12 still uses the common slip
s
clutch design found on many other drills. Spring
loaded steel balls press against the recesses of the
clutch ring. When the torque of the motor exceeds
the force of the spring loaded balls, the clutch ring
what it takes to click a ballpoint pen.
To detect when the clutch ring is slipping
ar
(rotating), two small, rare earth magnets are
inserted into the clutch ring. When these pass by a
sensor located inside the motor housing, a signal is
sent to the controller, and the controller turns off
n at
the motor.
lutch
3
spins, which disables the first-stage planetary
gear s et.
This design is commonly used because
it is robust, and only a tiny fraction of
the motor's power is needed to disengage
the clutch ring. As a matter of fact, the
pressure on the clutch balls is less than