Guidelines To Solve Shimmy Problems - Quickie Puma 20 Technical Manual

Puma 20/40

5.5 Guidelines to solve shimmy problems

If the castor wheels shimmy at a higher speeds (≥10 km/h), check the following points:
Possible cause Check
The anti-shimmy Check the anti-shimmy set:
set does not In case of a 10kmh Puma, the castor fork
function properly. should only make a half/three-quarter turn
when pushed (with its wheel of the ground).
In case of a 12.5kmh RWD Puma, the castor
fork should only rotate a quarter to a half
turn (since this is equipped with a different
disk spring).
Not enough Check the setting of the seating system.
pressure on the Normally the Center of Gravity setting
castor wheels. should be the same as the back depth (6-6,
10-10 etc).
There is not Check the environment of use; is the
enough friction wheelchair mainly used at higher speed
in the front fork outdoors, or more indoors (on carpet)?
for this specific
user and/or
configuration.
High tire pressure Check the tire pressure of the castor wheels.
(air castors only).
Solution
If the castor fork turns to loose; replace the anti-shimmy
set, as described in the mounting instruction 5.2.2 Step 6
Change the position of the castor wheels..
In case of a light-weight user, it might help to set the CoG
setting of the seating system a little more towards the
castors. Adjust the setting as described in the Sedeo
user manual. This will result in more pressure on the
castor wheels.
Note; adjustment of the seating system should always
be done with caution, since incorrect weight distribution
might negatively affect drive performance and comfort.
In the case that the other solutions are not sufficient or
unwanted: the anti-shimmy set can be adapted with a
thicker disk spring (XT), which will increase the friction
in the fork. (A 12.5 km/h RWD is standard equipped with
this XT disk spring 9008818).
Note; the thick disk spring will cause the fork to turn less
easy. This can have a negative effect on behavior on
carpet, in combination with heavy users.
The tires can be inflated up to 3.5 bar; in case of shimmy
problems, it might help to lower the tire pressure of the
castor wheels (min. is 1.5 bar).
Note; This is not a preferred solution. Lower tire pressure
will result in more friction between the wheel and ground.
This can cause problems when turning on carpet and can
have a negative effect on the range.
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