When the first gear is engaged, the synchronizer clutch connects the small ring gear 6 with the synchronizer hub, which has a rigid connection with the secondary shaft. In this case, the torque is transmitted from the primary shaft to gear 6 and through clutch 7 to the synchronizer hub and to the secondary shaft. When the second gear is engaged, clutch 7 connects the toothed ring gear 8 with the synchronizer hub, and the torque is transmitted to the secondary shaft through gear 8, clutch 7 and the synchronizer hub.
When the third gear is engaged, the synchronizer clutch 21 connects the gear 2 with the hub 12, and when the fourth gear is engaged, the same clutch connects the gear 13 with the hub 12, and the torque in both the first and second cases is transmitted through the parts connected by the clutch. When the fifth gear is engaged, the clutch 3 (see figure 62) connects hub 4 with the ring gear 2, and the torque from gear 7 is transmitted to gear 2 and through the synchronizer parts to the secondary shaft.
The operating principle of the synchronizer when engaging the fourth gear is shown in Figure 66.
Figure 66. Operation diagram of the synchronizer for III and IV gears:
I - neutral position; II - start of engagement of IV gear; III - completion of alignment of angular velocities of gear 1 and shaft 9; IV - full engagement of IV gear;
1 - driven gear of the 4th gear; 2 - blocking ring; 3 - sliding clutch; 4 - retainer ball; 5 - retainer spring; 6 - retainer cracker; 7 - driven gear of the 3rd gear; 8 - synchronizer hub; 9 - secondary shaft.
With the sliding clutch in neutral position 3 (figure 66, I) crackers 6 are located in the center of the grooves of the hub 8 and do not act on the blocking ring 2. Between the projections A of the blocking ring and the grooves of the hub there is a uniform lateral gap B, and between the projections A and the crackers there is a gap C.
When engaging IV gear (see figure 66, II) sliding clutch 3, moving towards gear I, carries along crackers 6, which rest against the ends of projections A of the locking ring and press it against the conical surface of the synchronizer ring. Under the action of friction forces between the conical surfaces of the locking ring and the synchronizer ring, as well as the inertial forces of the synchronized masses, the locking ring rotates relative to the hub until the projections of the ring rest against the side walls of the hub grooves. That is, on the other side of the projections, the gap increases twofold and will be equal to 2B. Due to the circumferential displacement of the locking ring by 1/4 of the pitch, the lateral bevels of the sliding clutch rest against the bevels of the teeth of the locking ring and further axial movement of the sliding clutch 3 stops until the angular velocities of gear 1 and shaft 9 are equalized (see fig 66, III). At this point, the friction cones of the locking ring 2 and gear 1 stop slipping and the force pressing the beveled surfaces of the teeth and the clutch and ring disappears. The released clutch easily moves along the hub, connecting it to the synchronizer ring (see figure 66, IV).