Drive and Low Range (Mechanical Powerflow)
When the range selector lever is placed in the Drive (D) position, the mechanical power flow through the variable drive and driven pulleys is allowed to run the full variable ratio range, from the lowest ratio to highest ratio.
1. Forward Clutch and Turbine Shaft Driven
As the torque converter turbine rotates, the turbine shaft of the forward clutch (106), which is splined to the torque converter turbine, is also forced to rotate at turbine speed.
2. Forward Clutch Applied
The forward clutch plates (309 - 311) which are splined to the reverse sun gear (308) and the forward clutch housing (302) are applied and connect the variable drive pulley to the forward clutch (106).
3. Variable Drive Pulley Driving
The variable drive pulley now drives the variable drive chain which is in contact with the variable driven pulley.
4. Variable Driven Pulley Driven
The variable driven pulley transfers torque to a transfer gear that is splined to the pulley assembly.
5. Power to Front Differential Drive Pinion
Torque is then transferred to the front differential drive pinion (8) from the variable driven pulley transfer gear.
6. Power to Front Differential Carrier
The front differential drive pinion (8) is in mesh with the front differential carrier (23) and thus power is transferred to the differential carrier and to the output shafts.
Low Range
Low range is available to the driver when vehicle operating conditions make it desirable to use a low range of drive ratios.
These conditions include descending a steep grade when maximum engine compression braking is needed, to retain a low range of drive ratios when ascending a steep grade, or pulling a heavy load for maximum engine power.
Power flow for Drive and Low is exactly the same except the ratio is changed (controlled) differently in each range. Drive range allows the full range of ratios from high to low. Low is limited to only the lower ratios.