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                                                                     Exhibit 5.1


                                 [Letterhead of]
                                  CUMMINS INC.


                                                               November 21, 2001

                             CUMMINS CAPITAL TRUST I
                     $300,000,000 7% CONVERTIBLE CUMULATIVE
                           QUARTERLY INCOME PREFERRED
                               SECURITIES (QUIPS)


Ladies and Gentlemen:

                  As Vice President - General Counsel and Secretary of Cummins
Inc., an Indiana Corporation (the "Company"), I am rendering this opinion in
connection with the Registration Statement on Form S-3 (File No. 333-68592), as
filed by the Company and Cummins Capital Trust I, a Delaware statutory business
trust (the "Trust") with the Securities and Exchange Commission on August 29,
2001 under the Securities Act of 1933, as amended (the "Securities Act"), and
Amendment No. 1 thereto, as filed on the date hereof (the registration
statement, as so amended, being hereinafter referred to as the "Registration
Statement") relating to the registration of the Trust's 7% Convertible
Cumulative Quarterly Income Preferred Securities (QUIPS) (liquidation amount $50
per preferred security) (the "Preferred Securities"), which are convertible into
common stock, par value $2.50 per share (the "Common Stock"), of the Company.
The Preferred Securities were issued pursuant to the Amended and Restated Trust
Agreement dated as of June 18, 2001 (the "Trust Agreement"), among the Company,
as Depositor, BNY Midwest Trust Company, as trustee (the "Trust Agreement
Trustee"), and the Administrative Trustees named therein and are guaranteed by
the Company (the "Guarantee") to the extent set forth in the Guarantee Agreement
dated as of June 18, 2001 (the "Guarantee Agreement"), among the Company, as
Guarantor, the Trust and BNY Midwest Trust Company, as trustee (the "Guarantee
Trustee"). The Trust has acquired $309,278,400 aggregate principal amount of 7%
Junior Subordinated Convertible Debentures of Cummins Inc. (the "Debentures")
with the proceeds from the sale of the Preferred Securities and the sale to the
Company of the common securities of the Trust. The Debentures were issued
pursuant to the Indenture dated as of June 18, 2001 (the "Indenture") between
the Company and BNY Midwest Trust Company, as trustee (the "Indenture Trustee").

                  In that connection, I have examined originals, or copies
certified or otherwise identified to my satisfaction, of such documents,
corporate records and other instruments as I have deemed necessary or
appropriate for the purposes of this opinion, including: (a) the Certificate of
Incorporation of the Company, as amended, (b) the By-laws of the Company, (c)
resolutions adopted by the Board of Directors on April 3, 2001, by the Executive
Committee on June 12, 2001, and by the Pricing Committee on June 12, 2001, (d)
the Trust Agreement, (e) the Guarantee Agreement, (f) the Indenture (g) a
specimen of the Preferred Securities, (h) a specimen of the Debentures, (i) a
specimen certificate of the shares of Common Stock of the Company and (j) the
Registration Statement.

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                  In my examination of the aforesaid documents, certificates and
other documents, I have assumed that any documents purporting to be originals
are authentic and any copies of documents conform with the originals of such
documents.

                  Based upon the foregoing, I am of opinion as follows:

                    1.   The Company has been duly incorporated and is validly
                         existing as a corporation in good standing under the
                         laws of the State of Indiana.

                    2.   All the shares of Common Stock issuable upon conversion
                         of the Preferred Securities and the Debentures have
                         been duly and validly authorized and reserved for
                         issuance upon such conversion and, when issued and
                         delivered in accordance with the terms of the Preferred
                         Securities and the Debentures, will be duly and validly
                         issued, fully paid and non-assessable.

                    3.   The Guarantee and the Debentures have each been duly
                         authorized, issued and delivered, and the Debentures
                         have been duly executed, by the Company.

                  I hereby consent to the filing of this opinion as an exhibit
to the Registration Statement. I also consent to the use of my name under the
caption "Legal Matters" in the Prospectus contained in the Registration
Statement.

                  This opinion is being delivered to you in my capacity as the
Vice President - General Counsel and Secretary of the Company and solely for the
purpose of being included as an exhibit to the Registration Statement. This
opinion addresses matters only as of the date hereof and may not be relied upon
in any manner for any other purpose without my prior written consent.


                                               Very truly yours,

                                           /s/ Marya M. Rose


Cummins Inc.
Cummins Capital Trust I
     c/o Cummins Inc.
         500 Jackson Street, Box 3005
              Columbus, IN 47202-3005