Cat officials said the ministry gave its formal approval on April 17, allowing the OEM to move ahead with the transaction.

ERA primarily manufactures and sells underground equipment in mainland China through a subsidiary, Zhengzhou Siwei Mechanical and Electrical Equipment Manufacturing, commonly known as Siwei.

Siwei has a 600,000sq.m manufacturing base at Zhengzhou in the Henan province, where it manufactures and sells roof support equipment.

Its employees will be retained by Cat.

In November 2011, Cat said it had identified the mining industry and improving customer support as its key imperatives for its 2015 strategy.

“Our announcement … underscores Caterpillar's long-term commitment to continue to invest in China in order to support our growing base of Chinese customers,” Caterpillar group president Steve Wunning said at the time.

“We intend to build on Siwei's strong reputation and relationships in China, further investing in its mining roof support business and operations, while utilizing Caterpillar's global reach and organization to help bring Siwei's products to more customers outside of China.”

ERA chairman Emory Williams said Cat had been an important contributor to equipment, safety and mining practice improvements globally.

Siwei chairman and chief executive officer Wang Fu, who will continue to head the company, added: “Caterpillar has developed a reputation for its community involvement and contributions to society in the communities where it operates and for the strong relationships it has with its employees.”

The two made a joint announcement last year of the pre-conditional voluntary offer for all ERA shares to be bought by Cat subsidiary Caterpillar (Luxembourg) Investment.

Caterpillar’s offer consists of two options, one including an all-cash alternative to acquire the shares for HK88c cash per share, and/or a loan note alternative, which will provide a minimum of 75c and up to $1.15 per loan note upon redemption.

ERA shareholders will elect to receive one or the other or a mix of the two.

“Caterpillar has a long history in China and during the past three decades, Caterpillar has grown from a single sales office in Beijing to a cross-country footprint today – which includes 16 locations for manufacturing, four research and development facilities, three logistics and parts centers and other offices,” the company said.

“In addition, Caterpillar has made significant investments in China and announced a wide range of new facilities, with a total of nine new facilities under construction.”