Tata Pixel zero turn demonstrator

The Tata Pixel zero turn (ZT) project brought together TMETC’s 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.

Project challenges

A number of novel solutions had to be integrated by TMETC 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 TMETC teams to integrate a series of novel solutions, out-of-the-box thinking and utilisation of advanced engineering simulation tools.

Project outcomes

Despite the numerous hurdles, including some final control software problems to drive the double gearbox ZT system, which required additional time to fix, the test drive was held with journalist Ian Adcock of Auto Express, who reported: “The ZT technology in this Tata Pixel is a shining example of lateral thinking by British engineers.” He added: “The best part about the Pixel’s ridiculous turning circle is that it demands absolutely no compromises. During normal driving, the Tata Pixel feels identical to a conventional car.”

The Tata Pixel ZT concept demonstrator is another example of Tata Motors’ daring new design and engineering innovation through its UK R&D centre, TMETC.

A patent has since been applied for - the first for a zero turn road car front suspension.

In focus: How is the ‘zero turn’ accomplished?
  • 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 shaft 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