What's the reason for the transmission not shifting gears?

[VanAdam]

Transmission not shifting gears may be caused by transmission oil pump failure, transmission valve body failure, control module failure, and other reasons. The relevant introduction to the transmission is as follows: 1. Function: The transmission is a gearbox that changes the transmission ratio and direction of motion, located between the clutch and the central drive. Its main functions are to change the vehicle's driving force and speed (shifting) when the engine speed and torque remain unchanged, to enable the vehicle to drive in reverse (direction change), and to allow the engine to stop without stalling (neutral). 2. Classification: According to the transmission type, gear-type transmissions can be divided into three types: double-shaft type, three-shaft type, and composite type. The double-shaft type has two main shafts (excluding the reverse gear shaft) and only undergoes one pair of gear reduction. The three-shaft type has three main shafts (first shaft, intermediate shaft, second shaft) and undergoes two pairs of gear reduction. The composite type consists of two transmissions connected in series or parallel to obtain more gear positions with fewer gears.