The Tata Pixel Zero Turn (ZT) project brought together the Design and Engineering teams’ to demonstrate a fully functional ZT prototype vehicle, following the introduction of the Tata Pixel concept car at the Geneva Motor Show in 2011.
The prototype would use a Tata Nano 2-cylinder rear-engine packaging configuration and have a ZT transmission for road test capability and functionality. It was to be completed in nine months to deliver test drives and to be featured in the British automotive press.
A number of novel solutions had to be integrated by the Design Tech centre engineers in order to accomplish a ZT passenger car, using the generic ZT ideas of the Tata Pixel concept car. These were tested in a completely virtual environment, as no prototypes existed to verify the validity of the concept. In addition, no other passenger vehicle of this kind existed in the market to assess, benchmark, gain experience or borrow ideas from.
Thousands of simulations were run in order to achieve the desired balance of attributes within the packaging constraints of the ZT. The requirement for a passenger car to rotate around the centre of its rear axle posed a number of challenges both in the steering and suspension design, well beyond those encountered in an ordinary vehicle. To address these challenges required the Tech centre teams to integrate a series of novel solutions, out-of-the-box thinking and utilisation of advanced engineering simulation tools.
- Key to the zero turn is the unique MacPherson front suspension and steering mechanism that allows the front wheels to tuck back into themselves when turning left or right at angles of up to 105 degrees.
- As opposed to a conventional MacPherson suspension, the knuckle is locked relative to the strut with an anti-rotation bearing.
- This extreme articulation range necessitated the use of a gearing system housed on the knuckle.
- The input gear, which rotates around the MacPherson strut on a bearing, is driven by the steering tie-rod.
- The output gear is directly connected to a s haft which rotates within the knuckle and essentially forms the steering axis.
- Last, but not least, during a zero turn the driving wheels counter-rotate with a use of a special gearbox unit.