Truck Transmission Gears Spiral bevel gear in our products is mainly Mainly refers to the basin Angle gear. The full name of basin Angle gear is: differential active and passive gear, divided into two parts of the main gear and passive gear, commonly known as disc Angle gear. It's in the rear axle main reducer. Basin Angle gear is called driven bevel gear terminology, is the engine speed through the car transmission after another speed down; Play the role of reducing speed and increasing torsion. title1 title1Truck Transmission Gears website:http://www.china-tractorparts.com/truck-gears/truck-transmission-gears/