Transmission General Description

WARNING: This page is about a different variant/trim than selected.

The VT40 is a fully-automatic, electro-hydraulic controlled, 4 - axis single mode continuously-variable, front-wheel drive transmission. It consists primarily of a four-element torque converter, one planetary gear set, an electronic hydraulic pressurization and control system, a variable drive and driven pulley assembly, variable drive chain, two friction clutches, and a differential assembly.

The four-element torque converter contains a pump, a turbine, a pressure plate splined to the turbine, and a stator assembly. The torque converter acts as a fluid coupling to smoothly transmit power from the engine to the transmission. It also hydraulically provides additional torque multiplication when required. The pressure plate, when applied, provides a mechanical "direct drive" coupling of the engine to the transmission.

The planetary gear set provides REVERSE. Changing drive ratios is fully automatic and is accomplished through the use of a transmission control module (TCM). The TCM receives and monitors various electronic sensor inputs and uses this information to control the transmission ratios at the most optimum time.

The hydraulic system primarily consists of a vane type pump, a control valve body, a control valve solenoid body, a case and a case cover. The pump maintains the working pressures needed to stroke the clutch pistons that apply or release the friction components. These friction components, when applied or released, support the forward or reverse ranges of the transmission.

The hydraulic system supplies pressurized fluid to the variable drive and driven pulley assemblies to provide accurate variable ratio-controlled output torque to the differential.

The VT40 is also equipped with an electric auxiliary fluid pump. This pump is used to keep hydraulic circuits primed during an automatic stop/start event.

The transmission can be operated in any one of the five different positions shown on the shift quadrant.

PARK (P): This position enables the engine to be started while preventing the vehicle from rolling either forward or backward. For safety reasons, the vehicle parking brake should be used in addition to the transmission "PARK" position. Since the front differential carrier assembly is mechanically locked to the case through the park pawl, variable driven pulley assembly and front differential drive pinion gear assembly, PARK position should not be selected until the vehicle has come to a complete stop.
REVERSE (R): This position enables the vehicle to be operated in a rearward direction.
NEUTRAL (N): This position enables the engine to start and operate without driving the vehicle.
DRIVE (D): Drive range should be used for all normal driving conditions for maximum efficiency and fuel economy. Drive range allows the transmission to operate in the full range of variable ratios. DRIVE allows low to high ratios without any limitations, and torque converter clutch apply.
The transmission should not be operated in DRIVE when towing a trailer or driving on hilly terrain. Under such conditions that put an extra load on the engine, the transmission should be driven in a lower range selection for maximum efficiency.
LOW (Low): This position can be selected at any vehicle speed. If the transmission is in DRIVE, it will immediately change the ratio to low when vehicle speed is below approximately 56 km/h (35 mph). This is particularly beneficial for maintaining maximum engine braking when descending steep grades. With LOW range selected, the variable drive and driven pulleys will not be allowed to achieve high ratios