4LO Lock Mode Power Flow
When the BW 4493, shown, or the BW 4494, shown in inset, shifts the transfer case to the 4LO Lock mode, it commands the encoder motor (7) to turn the shift cam shaft (8), to rotate the shift cam (9). The range cam profile on the shift cam (9) moves the high/range shift fork (10) and the high/low range sleeve (4) rearward to the 4LO Lock range position. The high/low range sleeve (4) outer teeth disengage from the input shaft (1) high-speed teeth. The high/low range sleeve (4) outer teeth then engage in the high/low planetary carrier teeth (11). The power flow is now from planetary teeth on the input shaft (1) to the planetary gears (2) in the carrier. Rotating the planetary gears, which are engaged in the ring gear (3), rotates the planetary carrier. The planetary carrier delivers the power to the high/low range sleeve (4). The high/low range sleeve (4) then drives the mainshaft (5), providing a 2.64:1 reduction to the speed of the mainshaft (5). When in the 4LO Lock position, the lockup mode shift fork and lockup shift assembly (6) engages in the same way as in the 4HI Lock mode.