4LO Power Flow

WARNING: This page is about a different car, the 2007 Isuzu i-370, 2007 GMC Canyon, and 2007 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: 4LO Power Flow

Courtesy of GENERAL MOTORS CORP.

When shifting the transfer case to 4LO range, it commands the actuator assembly (200) to rotate the control actuator cam (262). The control actuator cam (262) shifts the high/low range sleeve (230) to low range, while keeping the 2/4 wheel drive synchronizer (220) engaged in the 4WD position.

The high/low shift fork (258) moves the high/low range sleeve (230) rearward. The high/low range sleeve (230) outer teeth disconnect from the high-speed teeth on the input shaft (105). The high/low range sleeve (230) outer teeth now engage with the low range gear (102). The low range gear (102) is tooth to the planetary carrier (112).

The outer teeth, or low range teeth, on the input shaft (105), which now acts like a sun gear, delivers the engine power to the pinion gears (108) in the planetary carrier (112). Rotating the pinion gears (108), which are engaged in the annulus gear (117), rotates the planetary carrier (112). The planetary carrier (112) delivers the power to the high/low range sleeve (230). The high/low range sleeve (230) then drives the rear output shaft (124), providing a 2.48:1 reduction to the speed of the rear output shaft (124). The 2/4 wheel drive synchronizer is still engaged, and engine torque is delivered to front and rear propeller shafts.