Chevrolet Equinox Service Manual: Transmission General Description Automatic Transmission Unit

The Hydra-matic 6T70/75 is a fully automatic, 6-speed,front-wheel drive, electronic-controlled transmission. It consistsprimarily of a 4-element torque converter, a compound planetarygear set, friction and mechanical clutch assemblies, and ahydraulic pressurization and control system. There are2- variants of the transmission, based on torquecapacity. Architecture is common between the variants, andcomponent differences are primarily related to size.

The 4-element torque converter contains a pump, a turbine, apressure plate splined to the turbine, and a stator assembly. Thetorque converter acts as a fluid coupling to smoothly transmitpower from the engine to the transmission. It also hydraulicallyprovides additional torque multiplication when required. Thepressure plate, when applied, provides a mechanical direct drivecoupling of the engine to the transmission.

The planetary gear sets provide the 6-forward gearratios and reverse. Changing gear ratios is fully automatic and isaccomplished through the use of a transmission controlmodule-(TCM) located inside the transmission. The TCMreceives and monitors various electronic sensor inputs and usesthis information to shift the transmission at the optimumtime.

The TCM commands shift solenoids and variable bleed pressurecontrol solenoids to control shift timing and feel. The TCM alsocontrols the apply and release of the torque converter clutch whichallows the engine to deliver the maximum fuel efficiency withoutsacrificing vehicle performance. All the solenoids, including theTCM, are packaged into a self-contained control solenoid valveassembly.

The hydraulic system primarily consists of a vane-type pump,2-control valve body assemblies, transfer drive gearsupport assembly and case. The pump maintains the working pressuresneeded to stroke the clutch pistons that apply or release thefriction components. These friction components, when applied orreleased, support the automatic shifting qualities of thetransmission.

The friction components used in this transmission consist of5-multiple disc clutches. The multiple disc clutchescombine with one way clutch to deliver 7-different gearratios, 6-forward and one reverse, through the gearsets. The gear sets then transfer torque through the transfer drivegear, transfer driven gear and differential assembly.

The transmission may be operated in any of the following gearranges:

This position locks the front wheels and prevents the vehiclefrom rolling either forward or backward. PARK is the best positionto use when starting the vehicle. Because the transmission utilizesa shift lock control system, it is necessary to fully depress thebrake pedal before shifting out of PARK. For safety reasons, usethe parking brake in addition to the PARK position.

This position allows the vehicle to be operated in a rearwarddirection.

This position allows the engine to be started and operatedwhile driving the vehicle. If necessary, you may select thisposition in order to restart the engine with the vehicle moving.This position should also be used when towing the vehicle.

Drive range should be used for all normal driving conditionsfor maximum efficiency and fuel economy. Drive range allows thetransmission to operate in each of the 6-forward gearratios. Downshifts to a lower gear, or higher gear ratio, areavailable for safe passing by depressing the accelerator or bymanually selecting a lower gear in the manual mode range.

Thisposition-(M–Manual-/-L–Low)allows the driver to utilize the-DSC/ERS system. Whenthe shift selector lever is moved to this position, the driver mayselect upshifts or downshifts by using the paddle switches locatedon the steering wheel/shifter. An upshift is requested by pushingeither + button. Refer to the vehicle owner's manual for morespecific DSC/ERS information.