The function of the freewheel unit
A freewheel unit is connected to the viscous coupling. It
is located after the viscous coupling and has two functions:
– Dis-engaging rear-wheel drive during braking.
– Engaging four-wheel drive when reversing.
The freewheel unit has an input and an output shaft.
These shafts can be connected via a freewheel and via
a centrifugal roller lock-up mechanism.
The freewheel unit, which has a centrifugal roller lock-up
mechanism, also makes it possible to reverse with fourwheel
drive at up to approximately 50 km/h (30 mph).
Freewheel
– When driving forward, power can be transmitted from
the input shaft to the output shaft (rear axle) via the
freewheel.
– During braking the rear wheels may rotate faster than
the front wheels. In this case the freewheel is driven
in the " (opposite) direction by the output shaft.
No power can be transmitted this way because the
freewheel is free. The rear wheels can never drive the
front wheels thereby negatively affect braking stability.
– When reversing, the freewheel is driven by the input
shaft in the "opposite" direction. The freewheel is free
and cannot transmit power. In certain cases, power
can instead be transmitted via the centrifugal lock-up
mechanism.