Auto transmission needle roller bearing, also known as a guide bearing (fried dough twist bearing), is set at the joint between the concave bearing hole at the rear end of the first shaft of the transmission and the front journal of the second shaft. This guide bearing is usually evenly distributed with needle rollers of the bearing cage.

Auto transmission needle roller bearing can ensure that the first shaft and the second journal of the transmission are kept on the same centerline, and enable the first shaft and the second shaft to rotate independently, At the same time, it can disperse and reduce the wear of the two friction surfaces to the maximum extent.

When the transmission is shifted to the direct gear, although the needle bearing does not rotate, it plays a guiding role. When the transmission is shifted to another gear or neutral gear

The internal and external rotation of the needle roller bearing can make the two shafts rotate freely without being held back.

If the needle roller bearing at the rear end of the first shaft of the transmission is loose due to excessive wear, the load at the front end of the main shaft jumps, causing the transmission to shift out of gear directly, a pair of helical gears making abnormal noises at the fifth or fourth gear,

a pair of helical gears making abnormal noises at the third gear, or even two pairs of helical gears becoming more worn. Finally, the gear teeth are damaged or fall off due to excessive load, and the falling tooth pieces will also damage other gears with the splash of lubricating oil.

If the guide bearing is too tight at the connecting part of he two shafts for other reasons,it will prevent the second shaft from running freely during idling, and the gear like sound will occur during gear shifting. Words affect the shifting effect of the transmission.