Triple/S Slipstick horizontal motion accumulation conveyors consist of a seamless, sanitary conveyor trough and differential horizontal motion drive unit. The units convey products directly through the trough to the downstream packaging equipment. If an interruption occurs, a pneumatically actuated product dam located near the trough discharge is closed, and the conveyor drive speed is slowed; the discharge is equipped with a pneumatically actuated nose gate that works in conjunction with the product dam to provide a controlled discharge of the accumulated product. Meeting USDA standards, the conveyors are constructed of all stainless steel to accommodate heavy washdown requirements. They are available in sizes from 20 to over 200 cu. ft.