5D2-2 TRANSFER CASE - TOD GENERAL INFORMATION AND OPERATION TOD system means the full time 4WD system and the registered trade mark of Borg Warner. TOD is an abbreviation of Torque On Demand. TOD control unit automatically tailors torque distribution to road, offering full time four wheel drive. TOD distributes electronically-controlled power into front and rear wheels whose ratio change from 0 : 100 to 50 : 50 complying with wheel speed differences. Also TOD control unit analyzes data from wheel speed sensor and engine output then changes pressure of electromagnetic clutch. This pressure controls front propeller shaft and power to front wheel.
Power to front wheel depends on degree of pressure corresponding clutch slip. TOD is designed to distribute the power to front and rear axle by operation of 4H/4L switch and shift motor. Shifting 4WD high (4H) to 4WD low (4L) is performed towards reducing high-low collar by means for connection high-low shift fork with output shaft in order to join with planetary gear. Torque transmits input shaft then sun gear rotating front planetary gear. Front planetary gear joins with output shaft and drives at low position. The TOD system has 2 selectable mode, 4H and 4L. 4H is the normal operating mode when drive of which gear ratio is 1:1 and 4L mode distributes power to front and rear wheels 50 :
50 of which gear ratio is 2.48:1. TOD SYSTEM FUNCTION 4H Mode The TOD system transfer case controls the clutch mechanism to comply with rotation in front and rear propeller shaft and if its difference exceeds the permissible range, corresponding power is distributed into front wheel through electromagnetic clutch (EMC). Hall effect speed sensors are located front and rear propeller shafts, send signals to TOD transfer case control unit (TCCU). The EMC coil is activated by variable current on exceeding difference of speed in front and rear propeller shafts. 4L Mode When select 4L mode, EMC is locked to apply maximum torque into front and rear propeller shafts.
Shift motor rotates also 4L position by rotation of cam thus propeller shaft torque changes from 1:1 to 2.48:1 by planetary gear set. Transfer Case Control Unit (TCCU) Transfer case control unit (TCCU) receives, front and rear propeller shaft speed, shift motor position and 4H/4L switch signals and controls electromagnetic clutch (EMC), shift motor. TCCU communicates with scan tool with K-line for diagnosis. It located under the front LH seat. SSANGYONG Y200