heaviest materials 36 sink to the bottom of the fluidized bed and migrate to the higher side 64 of deck 12 because of the deck vibration and friction fig3 and 4 show in perspective two complete gravity tables fig3 shows a pressure type gravity table 14a whereby fan 66 it is possible to have more than one fan also operates to pull air through air intakes 68 and distributes air up and through deck 12a to fluidize particles it can be seen that deck 12a is sloped in two directions as shown by arrows 70 and 72 gravity thus causes materials fed to deck 12a to travel down towards discharge end 18a and also has the lateral slope shown in fig2 additionally oscillation or vibration is lateral to the slope along the longitudinal axis of deck 12a as is shown by arrow 74 an appropriate motor or actuator means not shown would cause oscillation or vibration of deck 12a fig4 depicts an alternative type of gravity table 14b namely a suction type gravity table it operates essentially the same as gravity table 14a except that fan 76 creates a suction in hood 78 directly above deck 12b and pulls air through air intakes 80 from below deck 12b and through it to fluidize the particles on table 14b table 14b is similarly sloped in two directions between its feed entrance 16b and its discharge end 18b fig5 and 6 are top views of rectangular deck 12a and trapezoidal deck 12b of pressure gravity table 14a and suction gravity table 14b of fig3.