Carlyle Group LP and BC Partners agreed to buy United Technologies Corp.’s Hamilton Sundstrand industrial unit for $3.46 billion as the company raises cash to pay for the acquisition of Goodrich Corp.

The transaction will be financed with equity from the firms and third-party debt from a group of banks, BC Partners and Carlyle Group said Wednesday in a statement. The deal is expected to close in the fourth quarter, the companies said.

The sale will help pay for the $16.5 billion Goodrich purchase, a record for Hartford, Connecticut-based United Technologies. Chief Executive Officer Louis Chenevert is increasing his focus on aviation with the purchase, adding the world’s largest maker of aircraft landing gear to brands that include Pratt & Whitney jet engines and Sikorsky helicopters.

United Technologies’ Hamilton Sundstrand unit consists of three business: Sundyne, a maker of high-speed pumps and compressors used in oil and gas applications and chemical/industrial infrastructure; pump-maker Milton Roy; and Sullair, which produces compressors used to power air-driven industrial equipment and tools.

Revenue in 2011 totaled about $1.4 billion, United Technologies said in a presentation to investors and analysts in March.