The 42RLE is a four-speed transmission that is a conventional hydraulic/mechanical assembly controlled with adaptive electronic controls and monÂitors. The hydraulic system of the transmission conÂsists of the transmission fluid, fluid passages, hydraulic valves, and various line pressure control components. An input clutch assembly which houses the underdrive, overdrive, and reverse clutches is used. It also utilizes separate holding clutches: 2nd/ 4th gear and Low/Reverse. The primary mechanical components of the transmission consist of the followÂing: Three multiple disc input clutches Two multiple disc holding clutches Four hydraulic accumulators Two planetary gear sets Hydraulic oil pump Valve body Solenoid/Pressure switch assembly Control of the transmission is accomplished by fully adaptive electronics. Optimum shift scheduling is accomplished through continuous real-time sensor feedback information provided to the Transmission Control Module (TCM) portion of the Powertrain Control Module (PCM). The TCM is the heart of the electronic control sysÂtem and relies on information from various direct and indirect inputs (sensors, switches, etc.) to deterÂmine driver demand and vehicle operating condiÂtions. With this information, the TCM can calculate and perform timely and quality shifts through variÂous output or control devices (solenoid pack, transÂmission control relay, etc.). The TCM also performs certain self-diagnostic functions and provides comprehensive information (sensor data, DTCâs, etc.) which is helpful in proper diagnosis and repair. This information can be viewed with the DRBÂ scan tool. In first gear range, torque input is through the underdrive clutch to the underdrive hub assembly. The underdrive hub is splined to the rear sun gear. When the underdrive clutch is applied, it rotates the underdrive hub and rear sun gear. The L/R clutch is applied to hold the front carrier/rear annulus assembly. The rear sun gear drives the rear planetary pinion gears. The rear planetary pinion gears are forced to walk around the inside of the staÂtionary rear annulus gear. The pinions are pinned to the rear carrier and cause the rear carrier assembly to rotate as they walk around the annulus gear. This provides the torque output for first gear. The other planetary gearset components are freewheeling. The first gear ratio is 2.84:1.