Exciter apparatus

There is provided exciter apparatus having a cast housing ( 11 ) and mounting base ( 14 ) secured to mounts bolted to the side plates of screening apparatus. A pair of shafts are mounted for rotation in and extend out of both sides of the cast housing ( 11 ). A gear assembly is keyed to each shaft t form a gear train coupling the shafts. The outer ends of each of the shafts are provided with eccentric masses ( 30 ) aligned on their respective shafts 180° out of phase. Drive spools ( 35 ) are driven by electric motors (not shown). Coupling spools ( 37 ) are adapted to accept flexible couplings for joining exciter units together. The gears ( 26 ) comprise 9 teeth of an 18-tooth module at 325.0 mm pitch circle diameter (PCD) and 65 mm axial dimension. The lands between the teeth are at a notional diameter 262.6 mm, the teeth having a corresponding notional tooth height of 31.2 mm to the PCD. The gear tooth chordal length at 34 mm is oversize for the module and the gear tooth involute surface extends past the gear tooth addendum to meet a 6.5 mm radius tooth tip. This configuration gives a lash of 9°, which enables the direction of excitation to shift to track the center of gravity of the screen machine in use.