4LO Lock Mode Power Flow
When shifting the transfer case to the 4LO Lock mode, it commands the encoder motor (12) to turn the shift detent lever shaft (13), to rotate the shift detent lever cam (16). There are two cam profiles on the shift detent lever cam (16) functioning at the same time. The range profile on the shift detent lever cam (16) moves the high/range shift fork (18) and the high/low range sleeve (4) rearward to the 4LO range position.
The mode profile on the shift detent lever cam (16) moves the mode shift fork (17) rearward along with the mode shift collar (6).
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 (19). 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 annulus 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).
The mode shift collar (6) locks the mainshaft (5) to the drive sprocket (7). Torque is sent by the chain (14) to the front output shaft (15) and to the front axle.
The rear propeller shaft power flow is delivered by the case of the planetary carrier (8) being splined to the mainshaft (5). The power flows from the planetary carrier case to the rear pinion gears (11), to the rear sun gear (9), and to the rear output shaft (10).
The torque distribution in this mode is now determined by vehicle dynamic conditions and weight distribution. The planetary differential (8) is not operating, and both the front and rear propeller shafts are being driven at equal RPMs, therefore giving a 4 low lock mode. This mode should only be used for extra traction during off road use. Using this mode on dry pavement will cause tire scuffing.