Efficiency modeling of a ball traction infinitely variable planetary transmission
Year: 2026
Type: article
Abstract: Traction-based Continuously Variable Transmissions (CVTs) have attracted renewed interest due to their compactness, scalability and ability to provide smooth ratio variation through rolling contacts operating in the elastohydrodynamic lubrication (EHL) regime. Among these solutions, the NuVinci transmission employs a set of rotating balls to transmit torque between facing discs, enabling continuous ratio variation by tilting the ball rotation axes. Beyond conventional CVT operation, this architecture can be reconfigured into a Continuously Variable Planetary (CVP) unit and further into an Infinitely Variable Planetary (IVP) transmission, allowing power-split operation without additional mechanical paths. Building on previous modeling work on the NuVinci transmission in CVP configuration, this paper extends the efficiency formulation to IVP operation, where the ball carrier actively participates in power splitting and additional power-flow paths arise. A theoretical steady-state efficiency model of a ball traction Infinitely Variable Planetary transmission is developed, accounting for traction-contact behaviour and power-flow distribution. The model is applied to both single-idler and double-idler NuVinci configurations, enabling a comparative assessment of efficiency and traction capability and highlighting the influence of architecture and operating conditions on loss mechanisms.
Source: Mechanism and Machine Theory
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,060
OpenAlex ID: W7162185459