in rotation the article supporting rollers 17 are supported by gravity by the end lips 23 on the second surface 22 of each drive transmission roller 20 and the friction drag between these surfaces of engagement will cause the rollers 17 to rotate now as articles are placed on the conveyor the weight thereof will increase the contact pressure between the roller lip 23 and the second surface 22 thereby improving the drive at the before noted line contact in this arrangement it is important to have the diameter of the first surface 21 on the roller 20 sufficiently smaller than the outer diameter of the article supporting roller 17 so that articles are sure not to engage the first surface 21 as this first surface is intended to be engaged by the drive belt 25 a modified embodiment seen in fig4 includes the structure seen in the previous views thus the side rail 10 is seen supporting the article supporting rollers 17 below the upper flange so that the articles are guided during conveyance in this assembly every tenth roller 17a is a sensor and is supported on an arm 30 which is connected to the side rail 10 by the pivot 31 the arm reaches below the pivot and is connected to an actuator link 32 which includes a compression overtravel element to absorb motion of link 32 after the brake has been applied.