The need for knowledge of coefficient of friction of agricultural materials on various surfaces has long been recognized by engineers concerned with rational design of grain bins, silos and other storage structures. In the design of agricultural machinery, however, the need for this information has been recognized rather recently. Not finding this information in any handbook or published data, it became necessary to set up a friction test apparatus and obtain the information needed. We know

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... the internal friction angle metering devices in our laboratories have the low accuracy, thus we decided to design an automatic internal friction angle metering device with high accuracy which the tangent of this angle is equal to the coefficient of friction that be measured and displayed. This device is made up of one frame, three hinges, one electromotor with gearbox, one DC Adaptor, one wooden plate that can be changed, acceleration measuring sensor, laser transmitter and LDR for detection of movement, electrical circuit, Microcontroller and monitor for display of the angle and other devices for moving of the wooden plate and carrying of the materials.