Exhibit 5.1

December 8, 2025

Terex Corporation

301 Merritt 7, 4^th Floor

Norwalk, CT 06851

Re: Registration Statement on Form S-4

Ladies and Gentlemen:

We have acted as counsel to Terex Corporation, a Delaware corporation (the “Company”), in connection with the Company’s Registration Statement on Form S-4 (as amended from time to time, the “Registration Statement”) filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”), relating to the registration of up to 48,434,419 shares (the “Shares”) of the Company’s common stock, par value $0.01 per share. The Shares may be issued, as set forth in the Registration Statement, pursuant to that certain Agreement and Plan of Merger, dated as of October 29, 2025 (as amended from time to time, the “Merger Agreement”), by and among the Company, REV Group, Inc., Tag Merger Sub 1 Inc., and Tag Merger Sub 2 LLC. With your permission, all assumptions and statements of reliance herein have been made without any independent investigation or verification on our part and we express no opinion with respect to the subject matter or accuracy of such assumptions or items relied upon.

In connection with this opinion, we have (i) investigated such questions of law, (ii) examined the originals or certified, conformed, electronic or reproduction copies of such agreements, instruments, documents and records of the Company, such certificates of public officials and such other documents, and (iii) received such information from officers and representatives of the Company and others as we have deemed necessary or appropriate for the purposes of this opinion.

In all such examinations, we have assumed the legal capacity of all natural persons, the genuineness of all signatures, the authenticity of original and certified documents and the conformity to original or certified documents of all copies submitted to us as conformed, electronic or reproduction copies. As to various questions of fact relevant to the opinion expressed herein, we have relied upon, and assume the accuracy of, certificates and oral or written statements and other information of or from public officials and officers and representatives of the Company.

New York • Washington • London • Frankfurt • Brussels

Fried, Frank, Harris, Shriver & Jacobson LLP is a Delaware Limited Liability Partnership

Fried, Frank, Harris, Shriver & Jacobson LLP

December 8, 2025

Page 2

Based upon the foregoing and subject to the limitations, qualifications and assumptions set forth herein, we are of the opinion that the Shares, when issued by the Company in accordance with the terms and conditions set forth in the Merger Agreement and in the manner contemplated by the Registration Statement, will be validly issued, fully paid and nonassessable.

The opinion expressed herein is limited to the applicable provisions of the General Corporation Law of the State of Delaware, as currently in effect, and no opinion is expressed with respect to any other laws or any effect that such other laws may have on the opinion expressed herein. The opinion expressed herein is limited to the matters stated herein and no opinion is implied or may be inferred beyond the matters expressly stated herein. We undertake no responsibility to update or supplement this letter after the effectiveness of the Registration Statement.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the reference to this firm under the caption “Legal Matters” in the joint proxy statement/prospectus included in the Registration Statement. In giving this consent, we do not hereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission.

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