An installation for covering and uncovering a surface, the installation comprising: ▪ a tarpaulin mounted on at least one head beam; ▪ on either side of the tarpaulin, respective chains of links that are rigid in thrust, controlled in translation, and each including one end connected to the head beam to move the tarpaulin between a magazine for receiving the tarpaulin in an uncovered position and a position for covering the surface; ▪ two sprockets on a common axis, constrained to rotate together by a connection shaft and having teeth adapted to the links of the chains in order to control the movement of the chains in translation in a "covering" first direction for covering the surface and in an "uncovering" second direction opposite to the first for uncovering the surface; ▪ a series of carriages providing temporary connection between the tarpaulin and the chains and designed to be distributed along the tarpaulin in its surface-covering position; and ▪ at the magazine, a separator system for separating the tarpaulin from the chain in the uncovering direction, so as to retract the tarpaulin from the chain and store it, and so as to secure the tarpaulin to the chain in the covering direction; the installation being characterized: ▪ in that each carriage has at least one clamp adapted to grip temporarily a roller of a link of the chain and a locking unit for locking the grip of the clamp relative to the chain so as to prevent the tarpaulin being raised relative to the chain; and ▪ in that the installation includes an actuator system for actuating the locking unit in the magazine so as to block the carriage on the chain in the covering direction and so as to unblock the carriage from the chain in the uncovering direction. ▪ a tarpaulin mounted on at least one head beam; ▪ on either side of the tarpaulin, respective chains of links that are rigid in thrust, controlled in translation, and each including one end connected to the head beam to move the tarpaulin between a magazine for receiving the tarpaulin in an uncovered position and a position for covering the surface; ▪ two sprockets on a common axis, constrained to rotate together by a connection shaft and having teeth adapted to the links of the chains in order to control the movement of the chains in translation in a "covering" first direction for covering the surface and in an "uncovering" second direction opposite to the first for uncovering the surface; ▪ a series of carriages providing temporary connection between the tarpaulin and the chains and designed to be distributed along the tarpaulin in its surface-covering position; and ▪ at the magazine, a separator system for separating the tarpaulin from the chain in the uncovering direction, so as to retract the tarpaulin from the chain and store it, and so as to secure the tarpaulin to the chain in the covering direction; the installation being characterized: ▪ in that each carriage has at least one clamp adapted to grip temporarily a roller of a link of the chain and a locking unit for locking the grip of the clamp relative to the chain so as to prevent the tarpaulin being raised relative to the chain; and ▪ in that the installation includes an actuator system for actuating the locking unit in the magazine so as to block the carriage on the chain in the covering direction and so as to unblock the carriage from the chain in the uncovering direction. ▪ in that each carriage has at least one clamp adapted to grip temporarily a roller of a link of the chain and a locking unit for locking the grip of the clamp relative to the chain so as to prevent the tarpaulin being raised relative to the chain; and ▪ in that the installation includes an actuator system for actuating the locking unit in the magazine so as to block the carriage on the chain in the covering direction and so as to unblock the carriage from the chain in the uncovering direction.