3 minute read
February 2025 Hybrid & Electric Vehicle Corner
By Curt Ward, Professor at Joliet Junior College
Exploring the Toyota PC60 Hybrid Automatic Transmission
As I write this article, the winter holiday break is complete, and the spring term has begun. Recently, Toyota of North America donated a 2023 model year PC60 hybrid automatic transmission to our program. This single-motor hybrid design transmission was introduced to the United States in the Toyota Crown. This transmission is very different than the THS/HSD two-motor design that Toyota has used in their hybrids since their introduction. In this article I will share what I have learned during the initial teardown and how this unit can be incorporated in the hybrid and electric vehicle curriculum.
Toyota refers to the powertrain package as a “Dual Boost Hybrid System”. The single electric drive motor is sandwiched between a 2.4-liter turbocharged engine and an electronically controlled six-speed automatic transmission. According to Toyota, the engine provides 200-202 kW of power, and the electric drive motor provides 61-64 kW of power, depending on the application. The powertrain can be paired with the rear eAxle for all-wheel-drive applications.
The transmission is more compact than previous hybrid models used by Toyota (See Figure 1 – Transmission Assembly). The front inverter is mounted directly to the top of the transmission. The large diameter, flat-design electric drive motor with the engine disconnect clutch and the start clutch assemblies are in the front of the transmission where a torque converter would normally be located (See Figure 2 – Electric Drive Motor). The engine disconnect clutch, and the start clutch allows for electric only operation and to start the internal combustion engine. The friction elements in these clutch packs are designed to allow for improved fluid flow and increased cooling capacity. The drive motor is a permanent magnet design and uses a resolver to determine motor location, speed, and direction of rotation.
The Toyota PC60 transmission uses Toyota ATF WS (World Standard) transmission fluid; this is the recommended fluid for most modern Toyota automatic transmissions and is identified by part numbers like 00289-ATFWS or 08886-02305. One item that is unique in this hybrid transmission is the mechanical oil pump. Most hybrid transmissions incorporate an electric oil pump. This transmission relies on a chain-driven offset oil pump that is turned when the internal combustion engine is operating (See Figure 3 –Oil Pump on the facing page).
Behind the electric motor is an electronically controlled six-speed automatic transmission. The solenoids in the valve body directly control the hydraulic flow through the valve body (See Figure 4 – Valve body). A combination of input clutches and holding clutches act upon the planetary gear train to provide the six-forward gear ranges.
I will finish this article with the same offer I make after each of my presentations. If you are interested in getting started in the process of adding hybrid and electric vehicles to your curriculum or want more information, please feel free to reach out. I am more than willing to sit down in-person or online and share my experiences. Are you looking for a classroom textbook? Reach out to Pearson and ask for a review copy of the all-new Electric and Hybrid Electric Vehicle text that Jim Halderman and I co-authored. It is a comprehensive text covering all the latest information on the subject.
