Abstract: This invention is directed to a bow end used for sliding bow covering systems which utilizes a solid trolley rail or trolley rail cables or cable or tubular track, trolley wheels and a trolley base having a bow support. The trolley rails or cables are attached to each side of any open top unit or the track is attached along the side. The trolley bow end rides on the trolley rail or in the track without touching the trailer. The important difference in this concept is that the roller wheels are located substantially below the horizontal line of the top of the trailer unit, this allows for side delivery of the contents of the trailer without allowing the contents to effect the trailer trolley rails or cable. Also an extension for storing the bows and tarp in the open position extends out either the front or back end, thus not interfering with the open top of the dump unit. The unit is designed for use with any open to dump box.