Exhibit 2.2

ASSIGNMENT AND ASSUMPTION AGREEMENT

ASSIGNMENT AND ASSUMPTION AGREEMENT, dated as of November 21, 2004 (this “ Agreement ”), between Altra Holdings, Inc., a Delaware corporation (“ Holdings ”) and, its wholly-owned subsidiary, Altra Industrial Motion, Inc., a Delaware corporation (“ Altra ”).

W I T N E S S E T H:

WHEREAS, Holdings (formerly CPT Acquisition Corp.), Warner Electric Holding, Inc. (“ Warner ”) and Colfax Corporation (“ Colfax ” and, together with Warner, the “ Sellers ”) have entered into that certain LLC Purchase Agreement, dated as of October 25, 2004 (the “ LLC Purchase Agreement ”), pursuant to which the parties contemplated that Holdings would acquire all of the limited liability company interests of Power Transmission Holding LLC (“ PT Holding ”) from Sellers;

WHEREAS, in accordance with Section 11.05 of the LLC Purchase Agreement, Holdings desires to assign to Altra all of Holdings’ right, title and interest in, under and to the LLC Purchase Agreement; and

WHEREAS, Altra desires to accept such assignment and assumption of the LLC Purchase Agreement.

NOW, THEREFORE, in consideration of the foregoing and other good and valuable consideration, the receipt and sufficiency of which