Power Transmission

1. Figure 11 shows the complete transmission assembly with the proper name for each part.
2. Figure 12 shows the same assembly with a letter substituted for the gear name.  By using the letter designation, the function of the gears will be better understood when the same gear is referred to repeatedly.
3. In Figure 12, the transmission is in neutral.  All the main shaft gears are meshed squarely with the opposing lay shaft gears.  These gears will never become unmeshed, nor will they mesh with any other gears.  Even when their sliding gears move back and forth to their farthest point, they will retain at least a 60% mesh with their opposing gears.  This is what the name, "constant mesh transmission" means.
4. Some gears on both shafts are locked to the shaft either by splines or by being an integral part of the shaft.  In Figure 12, the "YES" or "NO" printed on each gear indicates whether that gear is locked to its shaft.  Note that if a gear is locked to one shaft, its opposing gear is not locked to the other shaft.  Remember this point in the following discussion.
5. The foot shift lever is pushed down to engage first gear from neutral.  The drum rotates so its grooves slide the shift fork connected to gear I to the left.  The engaging dogs on the left of gear I fit in the slots on the right of gear J, engaging them (see Figure 13).
6. The other shift forks do not move.  The power enters the transmission through the main shaft.  Gear A is locked to the main shaft and transmits the power to gear J on the lay shaft.  Gear J is not locked to the lay shaft, but gear I is. Since gear J and gear I are now engaged, the lay shaft turns.