Elements of a Drive Train

Here is a picture of a simple two-speed transmisssion.

If the clutch is engaged, the green shaft will turn at the same speed as the engine.

If the green shaft and gear are turning, the red shaft and gears as well as the two blue gears are turning. The two blue gears are turning at different speeds and "free-wheel" on the yellow shaft.

The purple collar is splined to the yellow shaft. It can slide left and right but always turns with the yellow shaft.

We have now shifted into First or Low gear.

Here, the collar is engaged with the blue gear on the right. So the yellow shaft is turning at the same speed as the right hand blue gear.

The blue gear on the left is turning faster but it has no effect on the yellow shaft.

If the collar were engaged with the left blue gear, the yellow shaft would be going faster and we would be in Second gear.

Here is a five-speed (plus Reverse) transmission.

The blue gears all move at different speeds and one of them (reverse) moves in the opposite direction because of the Idler Gear.

The gearshift lever can only move one collar out of its neutral position at any one time.