Is the NSK half toroidal transmission with geared neutral a threat?
The half toroidal IVT is requires a more complex and costly control system than the full toroidal IVT.
I have noticed a paper published by NSK relation to a half toroidal transmission with geared neutral. I was under the impression that only the full toroidal transmission could achieve geared neutral and Torotrak hold the patent over this feature?
The unique geometry and torque method of control of the IVT means that achieving geared neutral can be easily realised and it is inherently safe. This is not the case for the half toroidal, where although geared neutral is possible a complex control system is required and the components must be manufactured to very high tolerances adding to the cost of the transmission.
Torotrak’s patents relate to the control of the full toroidal variator rather than the geared neutral feature of a variator derived from gearing.
More information on the geared neutral feature of the IVT can be found in the technical paper “Delivery of IVT for a 5 litre SUV: Addressing the Concerns of Geared Neutral”
Click here for PDF version.
