Caster Wheels Flapping - PRO ACTIV TRAVELER 4all Ergo Operating Instructions Service Booklet

Operating instructions TRAVELER 4all Ergo & 4you Ergo
Spacer
Figure 85: Spacer on the caster wheel
When attaching the caster wheel, proceed as
described above in reverse order. Please
make sure that the spacers on the right and left
on the caster wheel are re-installed in the
caster fork before assembly. The tightening
torque of the axle fixing screws (AF 4 mm) is
7 Nm. We recommend that you only use
screws with polymer dry locking coating.
Screws without polymer dry locking coating
must be secured with screw locking fluid.

23.2 Caster wheels flapping

Uncontrolled swivelling backwards and for-
wards of the caster wheels around their axes
on the caster fork (while moving) is called "flut-
tering".
If the caster wheels start fluttering, then
immediately reduce the speed you are travel-
ling at to avoid the caster wheels jamming
sideways so as to avoid the risk of falling over.
The speed limit at which a caster wheel can
start fluttering, reduces with:

increasing size of the caster wheels

increase weight of the caster wheels

falling load on the caster wheels

decreasing caster length of caster wheels
The following options are available to counter-
act caster fluttering:

Fluttering can be reduced by reducing the
caster wheel diameter. This means install-
ing a small caster wheel in a different
wheel position in the caster wheel fork
(seat height thus remains the same) would
be one way of reducing fluttering. How-
ever, please note that using a smaller
caster wheel makes it more difficult to
overcome obstacles and makes tipping
necessary more often. The smaller the
caster wheel is, the more driving skill is re-
quired.

Another way to reduce fluttering would be
e.g. to use a light caster wheel with the
same diameter or, as described above,
with a smaller diameter.
Caster wheel for rotary axle
Wheel contact
point
Caster length
Figure 86: Caster length

It would also be possible to increase the
caster length. The caster length is the dis-
tance between the rotary axle of the caster
wheel fork projected onto the floor and the
wheel contact point. The wheel contact
point of the caster wheel trails so to speak
behind the rotary axle. The caster length
has a stabilizing effect on moving in a
straight line. Increasing the caster length
can be attained by mounting the caster
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