The invention provides an automatic balancing device for counterbalancing an out-of-balance mass present in a rotating body. The automatic balancing device (50) comprises a chamber (56) having an outer wall (54) and an axis (18), first and second counterbalancing masses (80a, 80b) constrained to move freely in a circular path about the axis (18) and within the chamber (56), and a viscous fluid (60) provided in the chamber (56) so as to provide viscous coupling between the outer wall (54) of the chamber (56) and each of the counterbalancing masses (80a, 80b). The counterbalancing masses (80a, 80b) are adapted and/or arranged such that, in use, the first counterbalancing mass (80a) leads the second counterbalancing mass (80b). Constraining means (90a, 92a, 94a, 94b) are provided so as to prevent the first counterbalancing mass (80a) from leading the second counterbalancing mass (80b) by more than substantially 180° when the device is in use. This arrangement minimises the excursion of the rotating body at the critical speed. Such an arrangement has application particularly in the field of washing machines in which the position and size of the out-of-balance mass is unpredictable and there is a need to increase the speed of rotation of the body from a relatively low speed to a relatively high speed.
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