benkelman beam apparatus beckmann beams deflectometer the road surface deflection instrument of 3.6 meters or 5.4 meters it used for the determination of the pure land to load or at very slow speed elastic load pavementdeflection value, can well reflect the way the overall strength. the beckmann beams deflectometer is used to determine the road elastic deflection index under static or very slow loading rate, thus to obtain the pavement overall strength. it is kind of common road testing equipment. technical parameters: ength:3600mm,5400mm　　　 lever ratio: 2:1 fulcrum to station before long:2400mm stiffness:at the center of the shaft hole for the fulcrum, in 1200 mm from fulcrum 200 g its deflection is not greater than 0.05 mm