The normal operation of belt conveyor must make the conveyor belt have a certain tension, and the equipment providing tension is the tensioning device. The so-called "tension" has two meanings: absorbing the elongation of the conveyor belt and providing tension for the conveyor belt. The functions of the general conveyor tensioning device are as follows:

1. Make the conveyor belt have enough tension to ensure that sufficient driving force can be generated between the conveyor belt and the transmission drum to prevent slipping;

2. Ensure that the tension at each point of the conveyor belt is not lower than a given value, so as to prevent the conveyor belt from spreading materials and increasing running resistance due to excessive relaxation between idlers;

3. Compensate the elastic and plastic deformation of the conveyor belt;

4. Provide the necessary travel for belt reconnection.

For long-distance and high tension conveyors, it is necessary to consider providing different tensioning forces in different working states to improve the service life of the conveyor belt. During the start-up and braking of the conveyor, in order to ensure the transmission of start-up and braking force, the tension distribution of the conveyor belt is also different. It needs to be considered that the tension required to meet the sag conditions of the conveyor belt under these two working conditions is also increased accordingly. Therefore, it is required to have a tension greater than that during normal operation in the process of start-up and braking. This requires that the tensioning device can provide corresponding tensioning force under different working conditions. In practical application, the water tank has been used as the tensioning device to inject water into the water tank before the start of the conveyor to improve the tensioning force. When the conveyor reaches the normal operation state, discharge the water and reduce the tension to meet the tension of normal operation.