Fisher & Paykel WA37T26EW Service Manual page 17

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The inner basket is free to move in a vertical direction. The position of the inner basket is
determined by the water level. At the base of the inner basket is a flotation chamber consisting of
a number of individual cells. When the machine is filling with water, the pressure on the air in
these cells increases as the water level rises until eventually the inner basket floats upwards and
disengages the driven spline from the drive spline. This action frees the agitator from the inner
basket and allows it to move freely in both directions.
When the water is draining, the pressure on the air trapped in the cells of the flotation chamber
decreases allowing the inner basket to settle back down onto the drive spline and re-engage the
driven spline, thus allowing the agitator and inner basket to turn as one unit. The floating basket is
also used to detect if the user has selected the correct water level for the size of the clothes load.
The point at which the basket starts to float is determined by the water level and the size of the
load. The greater the load, the more water is needed before the inner basket will float. By
detecting the point at which the basket floats, the machine can determine whether the correct
water level for the particular clothes load has been chosen by the operator. If the operator has
chosen a level that is too low for the load, the machine will override that choice and fill to the
correct level. This is to ensure optimum wash performance and minimal clothes wear. If the user
has selected a level that is higher than necessary, the machine will still fill to the users selected
level.
3.11.1 Detection of Inner Basket Float off Point – Basket Check
During fill the inner basket will rotate to ensure that the clothes are evenly saturated with water.
When the chosen water level is reached, and before the agitate cycle is started, the machine will
carry out inner basket float checks (basket check). The inner basket will stop and commence a
number of small agitate type actions. During this action the machine determines if the inner basket
has floated. If it has the machine will determine the required water level and check if the operator
has selected the correct level. If the inner basket has not floated, the machine will continue filling
and check again later. The water level at which the inner basket floats is not necessarily the same
as the final water level.
3.11.2 Detection of Inner Basket Re-Engagement – Basket Check
After the water has drained, the inner basket will sink down and re-engage onto the drive spline.
To ensure the inner basket has re-engaged correctly, the machine will carry out a basket re-
engage test sequence (basket check). Basket check consists of a series of short agitate type
actions before the spin cycle starts. A sound may be heard as the inner basket re-engages.
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