FRONT WHEEL DRIVE WITHOUT COMPROMISE. A
PRODUCT OF EXPERIENCE.
One way round the problem of engine size
in front wheel drive, is longitudinal location of the engine
block. But this may put some of the engine’s mass ahead of the
front axle. Adding rigidity where it’s undesirable in a
collision- and the weight where (multiplied by leverage) it
could create serious handling problems. This becomes more
serious with diesel engines, which are heavier than their
petrol equivalents.
By contrast, the CX enjoys access to a wide
range of compact petrol and diesel units which can be
transversly mounted, driving the front wheels.
The CX's suspension and steering geometry
and unique Varipower steering neutralise the other objection
to front wheel drive in large cars - torque steer, where
excessive power via the front wheels pulls the car off course.
This kind of planned engineering is the
clearest evidence of Citroën's fifty years experience in the
application of front wheel drive, aerodynamics and
safety-conscious design.
AERODYNAMICS AND SELF-LEVELLING
SUSPENSION, ANOTHER
PART OF THE STORY
Paradoxically, the CX's aerodynamic
performance is dramatically enhanced by its suspension system.
On the face of it, it seems obvious that a
car with a low drag co-efficient will be consistently
efficient.
But aerodynamics isn't just a matter of
styling and wind tunnel tests. On the road with occupants and
luggage, a car is subject to very different forces. Load a
conventionally sprung car with rear passengers and luggage and
the body's angle to the road - and hence its aerodynamic
profile change significantly.
Not so the Citroën CX. Its self
levelling hydropneumatic suspension maintains the same ride
height and body angle whatever the load or how the load is
distributed.
So the CX's drag coefficient, as measured
in the wind tunnel, is maintained in practice. A factor far
more significant than minor differences in theoretical drag
figures between one type of car and another,
The self-levelling system affects the
performance of the CX in other ways.
HYDROPNEUMATIC (HYDRO-FLUID
PNEU-AIR/GAS): A SIMPLIFIED
EXPLANATION.
Just as most cars sag as they're loaded,
so their handling is affected. Equally, an unladen van or
estate can have a hard ride and jittery handling.
The CX's suspension system eliminates these
problems because the conventional car's metal springing is
replaced by gas spheres.
A metal spring becomes progressively more
compliant as the load upon it increases. However the gas
spring becomes progressively LESS compliant as it is loaded.
In the CX, the gas spheres are connected
to cylinders at each wheel which are part of a powered
hydraulic circuit. As the car is loaded, the gas in the
spheres is compressed, but a pump and reservoir of
hydraulic pressure compensates for any vertical displacement
of the wheel restoring normal ride height and angle of the CX
to the road.
This permits the CX to be quite softly (and
thus comfortably) sprung, yet its ride height and
handling remain consistent whether you drive alone or with
maximum payload.
SELF LEVELLING AND SAFETY
The CX's suspension geometry gives the CX
anti-dive braking and anti-lift acceleration - the last being
significant because it can affect steering control and grip.
A LANDMARK IN CAR DESIGN.
The suspension's hydraulics are part of a
larger system which also powers the brakes and steering.
This gives the CX immense braking force,
available instantly to take vital milliseconds off the total
time the driver takes to respond. Full power is available from
the moment the engine starts. It is independent of engine
pressure or revs and with the engine stopped the brakes and
power steering are backed by the pressure reservoir. The
connection between suspension and braking is used to limit
maximum rear brake pressure proportional to rear payload - to
help prevent the rear wheels locking under clearance to avoid
obstacles on rough terrain or lower the body of the car to
facilitate loading or tow-hook hitching.
POWER STEERING THAT THINKS.
Conventional power steering can become
disconcertingly light at speed.
Though modern systems
usually compensate in some way for road speed few approach the
accuracy and feel of the CX's Varipower system. This
uses rack and pinion - more precise than recirculating-ball,
used in some cars. And an automatic self centering device with
a speed sensor to control the amount of effort required to
turn the wheel away from the straight ahead position.
Conventional systems merely reduce assistance at speed. Thus,
the CX's steering is quick and almost effortless in tight
traffic but, at speed, can feel more secure than unpowered
steering. And this feeling is quite justified - the CX's
steering and suspension geometry is designed to eliminate
directional instability caused by variations
in road surface. Some rear suspension systems subject
the car to a slight steering effect at the extremes of their
vertical travel, known as bump steer. The CX's true
trailing arm rear suspension and
equal-length arm front suspension preclude this effect
and the car remains on course with minimum corrections.
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