Mechanical convergence roadway deformation mechanical direct-reading instrument roadway convergence device for measuring tunnel from small changes in the roadway, and other engineering surrounding rock caverns surrounding any direction between two points, to project stability assessment, research project around rock and deformation of supporting the development of the law, to determine the purpose of reasonable support parameters. Convergence has been recognized as one of the measurement must be measured to measure underground engineering projects. The main technical indicators: (1) measuring range: 0-120mm; (2) measurement: extension spring scales to scales; (3) Accuracy: 0.05.