A display apparatus and a method for generating gate signal thereof are provided. The engine intake manifold includes an intake air distribution box having an intake inlet, and a plurality of intake branch pipes made of a synthetic resin that are provided in a vertical arrangement connected to a side wall of the intake air distribution box with downstream ends connected to a plurality of corresponding intake ports of the engine. A forehead support bracket is pivotally connected to the support arm. Each bristle tuft carrier retains at least one tuft of bristles. The box portion is free from the mechanical stress when the sleeve portion is rigidly fixed to the housing. The incorporation of the disc enclosure and the chassis section into a single piece eliminates the requirement for a separate damping system.