A low-pressure accumulation system and a conveyor belt in an accumulation conveyor for the use with the system. The belt, which is flanked on opposite sides by lines of gravity rollers, has a longitudinal lane of article-supporting belt rollers arranged in groups along the length of the conveyor belt. The groups are spaced apart from each at regular intervals. Trays sit atop the gravity rollers until they are lifted slightly higher by one of the slightly elevated groups of article-supporting belt rollers, which engage the bottom of the tray and convey it along toward a discharge end. Retractable stops selectively block the trays from advancing on the accumulation conveyor. The freely rotatable article-supporting belt rollers roll along the bottoms of any blocked and accumulated trays and provide low back pressure. The belt may also include low-friction rollers that ride on bearing surfaces below the belt to help lower friction between the belt and the conveyor structure while the belt is running.