an apparatus used in pairs , each formed of two components , a spring lift roller assembly , and a pair of spring lift lid rollers , all of which are attached to a mobile tank lid . the roller assembly is mounted at about the midpoint of the depth of the lid , while one of the spring lift lid rollers is mounted at each of the distal and proximal ends along the sidewall of the lid equally spaced from the spring lift roller assembly . the apparatus &# 39 ; s slra is disposed on and confined to a track and moves from a central position in the desired direction , left side or right side , for the lid raising . the lid rollers commence a ride on their own track above the slra &# 39 ; s track , during the travel of the roller assembly , and when that assembly has reached its maximum travel point , the bearing plates attached to and forming part of the roller assembly rotate such that the lid now overhanging the tank &# 39 ; s side walls , is in a position to and does rotate around the roller bearing of each roller assembly due to gravity , to open the access to the tank &# 39 ; s content and the lid assumes a generally vertical position , having moved from an original horizontal disposition . closing of the tank is carried out by a reversal of the process . this roll and lift motion is used for placement of material into the tank , but for dumping , the rear bottom opening or rear located side opening gate is opened by being rotated around the hinges on the end wall having such hinges , such that the total tank can be emptied upon having the front elevated or emptied while at rest in a level position by manual effort .