Constant mesh gears are seldom used for all speeds. Common practice is to use such gears for the higher gears, with sliding gears for FIRST and REVERSE, or for REVERSE only.
Now that you understand the basic parts and construction of a manual transmission, we will cover the flow of power through a five-speed synchromesh transmission. In this example neither first gear nor reverse gear are synchronized.
Reverse Gear Synchromesh Transmission
In passing from neutral to reverse, the first-reverse main shaft gear is shifted rearward to mesh with the reverse idler gear (fig. 4-20, view A). The sole function of this gear is to make the main shaft rotate in the opposite direction to the input shaft; it does not affect gear ratio.
Figure 4-20.- Power flow of a five-speed transmission.
