The friction pendulum measures the energy loss when sliding a standardized rubber shoe, attached to the end of the pendulum arm, pressed by a spring, on the test surface, which provides the value of the sliding resistance. When the arm oscillates, the frictional force between the shoe and the test surface is obtained by measuring the reduction in circular motion of the pendulum arm.
Depending on the test method, application or country, rubber shoes of different hardness are used.
This equipment is suitable for carrying out laboratory tests, as well as for measuring soils in service.