share: digg facebook twitter Automaker Daimler and Rolls-Royce Group Plc made a public takeover offer for Tognum on April 6, and argue that the deal will combine the three company's technological know how and market access. Tognum, located in Friedrichshafen, Germany, has 9,000 employees and makes diesel and gas generators, along with engines used in ships, trains, tanks and oil platforms.