20. What is the minimum number of U-joints that would have to be used in the drive shaft assembly of a tandem drive axle truck equipped with a hanger bearing on the front drive shaft?

In a tandem drive axle truck with a hanger bearing, the minimum number of U-joints required would typically be three. This consists of one U-joint at the rear axle, one at the front axle, and one at the hanger bearing where the front and rear driveshafts connect. This arrangement helps maintain proper alignment and accommodate the articulation needed during operation. Moreover, ensuring the U-joints are installed correctly is crucial for optimal performance. Common mistakes include misalignment during installation or using U-joints that aren't rated for the truck's specific torque and load requirements. Regular inspections and maintenance can help prevent premature wear and failure, ensuring a smooth and efficient drive system.