PHASE
DRIVE
Today, a modern CVT transmission no longer uses a cable for control.
It has been replaced by a unique drive motor. In essence, it is
a stepper motor, but what holds it apart from other motors is
the unique way that it drives. It not only has to be very accurate
about its position but it must exert a high torque load.
ZF CVT valve bodies used in the new Mini and Rover cars have
this type of motor. It can also be found on other vehicles such
as Nissan, Fiat etc. It is becoming more common because of its
versatility and accuracy as well as being able to produce the
required torque with a small motor. This is achieved by the
drive or control system.
It is commonly referred to as “quad Q drive”
A hand held controller using the same “quad Q drive”
electronics has been developed by Focus Technology Ltd to allow
you to test these motors during rebuild. It will allow you to
confirm that the motor can overcome the load spring in the valve
body and that full travel is achieved. The unit is simple to
use with only three controls. One control operates the motor
in one direction and a second in the opposite direction. The
third control is a reset if the unit draws too much current.
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Parts
