Abstract: An improved lever arm for a tilt tray sortation conveyor has formula defined unlatching and tipping cam sections. The tipping cam section imparts a constant angular acceleration of about 20 radians/sec..sup.2 to the tray during positive tipping. Such angular acceleration produces a maximum tangential acceleration for any article on the tray, approximately equal to or less than the acceleration of a free-falling body. An improved tray latch or index plate has an inclined cam resisting rebound of the tray after initial tipping. Integral shock absorbers disperse impact forces in tray tip-up apparatus and resist elongation of tip-up mounting pin holes.