6.10 Checking/Adjusting the Seating Centre of Gravity
CAUTION
Improper adjustment of the seating centre of gravity
Risk of tipping over, falling from the seating shell/seating system
►
Avoid extreme settings that could lead to tipping when adjusting the seat angle.
►
Always choose centre of gravity settings so that the holding forces are as low as possible for the attendant.
►
For transfemoral amputees, shift the seating centre of gravity forward. This improves the stability of the wheel
chair.
►
Do not reach into the adjustment mechanism when changing the seat tilt settings.
CAUTION
Incorrect mounting of the seat frame
Falling from the seating shell/seating system due to locking mechanism malfunction
►
The locking pins must fully engage on both sides in the locking plate on the seat frame in all positions over the
entire adjustment range. Only then is the support of the seat assured with extreme settings or when driving
over rough surfaces.
Checking the seating centre of gravity is required in order to ensure that the seat angle can be adjusted easily
when the user is seated.
In principle, the centre of gravity adjustment has the following effects:
Seating centre of gravity
Effect
Too far in front of the pivot point
Seat tilts far forward when it is unlocked;
high holding forces required during seat adjustment.
Too far behind the pivot point
Seat tilts far backward when it is unlocked;
high holding forces required during seat adjustment.
Setting Recommendations
The seating centre of gravity should be individually adjusted according to the clinical picture.
The qualified personnel has to decide whether it is better that the seat swings forward or backward when no hold
ing force is applied while the locking mechanism is released. If possible, the attendant who will later push the
wheelchair should be consulted here.
Setting the Seating Centre of Gravity
1) Loosen 3 x clamping screws on each of the seat adapters on both sides (see fig. 32, item 1; see fig. 33, item
2).
2)
Only if necessary:
loosen the seat plate supports if they obstruct the adjustment of the seat adapters (see
Page 13).
3) Slide the seat to the assumed seating centre of gravity on both sides.
4) Check the installation position. The distance between the front edge of the seat tube and the seat adapter must
be identical on both sides. The difference on both sides must not exceed
1.5 mm
.
5) Tighten all clamping screws to a torque of
10 Nm
.
6) Conduct a functional test of the locking mechanism:
→
Tilt the seat and lock it at various positions along the entire adjustment range.
→
Ensure that the tipping movement and locking function operate easily. The locking pins must fully engage
on both sides in the locking plate in all positions over the entire adjustment range. Reference point: the
locking pins protrude slightly from the locking plate (see fig. 16, item 1).
7) Test the seating centre of gravity setting:
→
Sit the user in the seat with the help of an assistant.
→
Tilt the seat and hold it in position. Only low holding forces should be required for tilting.
Adjusting the seating centre of gravity
If the results are not satisfactory, the setting has to be readjusted without the user in the seat, as follows:
Problem
Solution
Seat tilts far forward when it is unlocked;
high holding forces required during seat adjustment
Open the seat clamp and slide the seat back
20 | Ottobock
Adjustments
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