Allison Transmission Inc. has signed a deal to invest £8million in Torotrak’s gearless traction drive technology.

The multinational commercial manufacturer previously invested £9.6 million in Torotrak’s work on fuel efficiency and emission improvements in 2009.

This new announcement brings the total investment to £17.6 million up to April 2012.

Allison remains Torotrak’s largest shareholder with a 9% holding in the company.