CVT Acceleration Curves – Basic Concept

1st stage – Idle

　　The 1st stage, Idle. Once a vehicle is started, the engine is running at its lowest possible rpm. The clutch is not engaged, and the vehicle is not in motion. It’s just like when you stop at the traffic light.

2nd stage – Clutch Engage

　　The 2nd stage, clutch engaging. Engine rev is increasing, the clutch shoes overcome the strength of clutch springs to move outward and touch the clutch bell. It’s not fully engaged, so the vehicle is still not in motion.

3rd stage – Taking-Off

　　The 3rd stage is taking-off. The vehicle starts moving and the engine rpm keeps increasing. Though the centrifugal force on the roller weights equals to the preload strength of the torque spring, neither the driven face nor the belt is moving yet.

　　Low Ratio state starts from the 1st to the 3rd stages, where the 2nd and the 3rd stage covers pretty short period.

4th stage – Transmission Shifting

　　The 4th stage is transmission shifting. The thrust strength of the roller weights finally overcomes the preload strength of the torque spring; the movable driving pulley (of the driving pulley set) starts to move; and the belt goes from the lowest to highest position.

　　In this shifting period, the engine rev rpm remains almost the same, which forms almost a horizontal line in the chart.

　　It’s the most important stage during all transmission process. The heavier roller weights you use, the lower engine rev rpm (line) it is.

5th stage – Overload

　　The 5th stage is overload driving. At this stage, the transmission is nor more shifting and stays at high ratio. When the engine runs faster, the vehicle speed can increase.

　　By the way, the lighter roller weights you use, the shorter this 5th stage lasts.