« Back to Dictionary Index
A variable belt transmission, also known as a continuously variable transmission (CVT), utilizes rubber V-belts on expanding and contracting pulleys to provide seamless and infinite variability in gear ratios.
Functionality:
- Continuous Variation: Unlike traditional transmissions with fixed gear ratios, a CVT allows for smooth and stepless adjustment of the gear ratio. This means the engine can operate at its optimal speed for various driving conditions, leading to improved fuel efficiency and performance.
- Rubber V-Belts: In a variable belt transmission, power is transferred between the engine and wheels via rubber V-belts. These belts are connected to pulleys that can change in diameter, altering the effective gear ratio.
- Expanding and Contracting Pulleys: The pulleys in a CVT have movable sheaves that can expand or contract, changing the effective diameter of the pulley and thus adjusting the gear ratio. As the vehicle’s speed or load changes, the transmission continuously adjusts the belt position to maintain optimal engine speed.
History and Development:
- Origin: The concept of a CVT using rubber V-belts on expanding-contracting pulleys was developed by Hub van Doorne for DAF (a Dutch automobile manufacturer) in the 1950s.
- Commercialization: The CVT technology was first used in production vehicles by DAF, notably in models like the DAF 600 and later the DAF 33. The technology was later adopted by other manufacturers, including Volvo.
- Volvo 340: The Volvo 340, introduced in the late 1970s, utilized a CVT developed by DAF, featuring rubber V-belts and expanding-contracting pulleys. This transmission design provided smooth and efficient power delivery, contributing to the vehicle’s performance and fuel economy.
Benefits:
- Efficiency: CVTs are often more efficient than traditional automatic transmissions because they can keep the engine operating within its optimal power range more consistently.
- Smoothness: The continuously variable nature of a CVT results in smooth acceleration without the noticeable shift points associated with traditional transmissions.
- Adaptability: CVTs can adapt to various driving conditions and loads more effectively than fixed-ratio transmissions, providing better performance and fuel economy.
In summary, a variable belt transmission, or continuously variable transmission (CVT), utilizes rubber V-belts on expanding-contracting pulleys to provide seamless and infinite variability in gear ratios. Developed initially by DAF and later adopted by Volvo in models like the Volvo 340, this transmission design offers benefits in terms of efficiency, smoothness, and adaptability to driving conditions.
« Back to Dictionary Index