A power-assisted heavy lift chair comprises a base assembly. A chair frame is supported on the base assembly. A lift mechanism communicates with the base assembly and the chair frame, and is operable to actuate the chair frame between first and second positions. A transformer provides electrical power to an electric motor. The electric motor provides rotational power to the lift mechanism at a first rate to lift and/or lower the chair frame. The electric motor draws current from the transformer according to a load upon the chair frame. The rate that the electric motor lifts and/or lowers the chair frame depends upon the voltage provided by the transformer. The transformer is operable to provide a generally constant voltage regardless of the current draw of the electric motor. Therefore, the electric motor lifts and/or lowers the chair at a constant rate independent of the load on the chair.
An actuator usable in a support frame for use in a lift chair. In one embodiment, the actuator has a housing, a reversible electric motor positioned in the housing, a worm that connects with a worm wheel, wherein the worm is driven by the electric reversible motor in operation, an outer tube member that extends through an opening defined in a front end of the housing and has a central axis, an activation rod configured to be telescopically movable relative to the outer tube member, a first pushing member movable with the activation rod and having a threaded opening, a first protrusion member and a second protrusion member spaced apart from the first protrusion member, a first push button switch with a push button, and a second push button switch with a push button, the first push button switch and second push button switch electrically coupled to the electric reversible motor and positioned apart in the housing such that when, during operation, the motion of the activation rod relative to the outer tube member causes the first pushing member to move along with a direction parallel to the central axis, the first protrusion member engages with or disengages from the push button of the first push button switch to cause the first push button switch to be in a first state or in a second state.
