An Electromechanical California Bearing Ratio (CBR) Testing Machine is a laboratory apparatus used to determine the bearing capacity and strength of subgrade soils, base courses, and sub-base materials for pavement design. The machine applies a controlled vertical load to a standard penetration piston at a constant rate, while measuring the load required to penetrate the soil specimen. The applied load and corresponding penetration values are used to calculate the California Bearing Ratio (CBR), which indicates the suitability of the material for road and airfield construction.
The machine consists of a rigid loading frame, an electromechanical drive system, a load measuring device (load cell or proving ring), a penetration piston, and a digital display or computer-based data acquisition system.