4HI Lock Mode Power Flow
When the BW 4493, shown, or the BW 4494, shown in inset, shifts to the 4HI Lock mode, the encoder motor (4) turns the shift cam shaft (5), to rotate the shift cam (8). The action of the shift cam (8) moves the lockup mode shift fork rearward along with the lockup shift collar assembly (2). The lockup shift assembly sleeve (2) locks the mainshaft (1) to the drive sprocket (3). Torque is sent by the chain (6) to the front output shaft (7) and to the front axle. The torque distribution in this mode is now determined by vehicle dynamic conditions and weight distribution. The planetary differential is not operating, and both the front and rear propeller shafts are being driven at equal RPM, therefore giving a 4 high lock mode. This mode should only be used for extra traction during off road use. Using this mode on dry pavement causes tire scuffing.