As promised in last month’s Powertrain Pro article, we will take a brief look at the CVT-7 transmission in this month’s article (figure 1). If you recall, this little CVT can be referred to as the JF015E in Dodge, the RE0F11A in Nissan and the FICJB in Mitsubishi applications. As you can see in figure 1, torque input is delivered to the transmission through a conventional torque converter.
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There are 3 very interesting aspects to this CVT transmission. The first being a full complete apply of the converter clutch taking place at approximately 11 mph (10 km/h).
The second being the use of a low brake, high clutch and reverse brake located between the pulley assembly and the differential (figure 2). Similar to the way Honda places their Start Clutch as discussed in July’s Powertrain Pro article.
The third is the elimination of a stepper motor and ratio control valve to ratio the pulleys. This stepper motor and ratio control valve have been replaced with the use of Line Pressure Solenoid (A) and Primary Pressure Solenoid (B) as identified in figure 3.
It is a nicely compact little CVT and very pleasant to work on. If CVT transmissions have not been a transmission you would ever consider working on, this one might change your mind. It all comes apart and goes back together again very easily, including the Primary and Secondary Pulleys.
Having a low brake, high clutch and reverse brake located between the pulley assembly and the differential similar to the way Honda places their Start Clutch, allows for a variety of strategies and features. Smaller pulleys while achieving a 7.3 total ratio spread would be one advantage to this type of design. The placements of the pulleys are closer to being horizontally mounted rather than being closer to a vertical mount with the secondary pulley higher than the primary pulley. This provides a compact little CVT.
The location of the clutch and brake assemblies is referred to as the “Auxiliary Gearbox” section of the transmission which a ravigneaux planetary gear is a part of. The carrier is driven by the secondary pulley assembly through the carrier’s short shaft that spline into the pulley assembly. The High Clutch Drum contains the ring gear which locks to the carrier when the High Clutch is applied. The Reverse Brake spline to the High Clutch Drum and is used to hold the ring gear stationary. There is a sun gear and shell which the Low Brake is spline to holding the sun gear stationary when applied.
|Figure 1||Figure 2||Figure 3|