<DOCUMENT>
<TYPE>EX-5.1
<SEQUENCE>5
<FILENAME>y64752ex5-1.txt
<DESCRIPTION>OPINION RE LEGALITY
<TEXT>
<PAGE>   1
                                                                     Exhibit 5.1


                                                                  212-859-8272
August 28, 2001                                              (FAX: 212-859-8589)

SPX Corporation
700 Terrace Point Drive
Muskegon, MI 49440

Ladies and Gentlemen:

                  We are acting as counsel to SPX Corporation, a Delaware
corporation (the "Company"), in connection with the Registration Statement on
Form S-3, as amended (the "Registration Statement"), under the Securities Act of
1933, as amended (the "Securities Act"), with respect to the contemplated
issuance by the Company from time to time of up to U.S. $1,000,000,000 aggregate
public offering price or the equivalent thereof in one or more foreign
currencies, currency units or composite currencies of (i) shares of the
Company's common stock, par value $10.00 per share (the "Common Stock") and (ii)
one or more series of senior or subordinated debt securities of the Company (the
"Debt Securities"), which may be issued pursuant to a senior debt indenture (the
"Senior Indenture") or a subordinated debt indenture (the "Subordinated
Indenture," and, together with the Senior Indenture, each an "Indenture" and
collectively, the "Indentures") to be entered into between the Company and The
Chase Manhattan Bank, as trustee (in such capacity, the "Trustee"). All
capitalized terms used herein that are defined in the Registration Statement
have the meanings assigned to such terms therein, unless otherwise defined
herein. With your permission, all assumptions and statements of reliance herein
have been made without any independent investigation or verification on our part
except to the extent otherwise expressly stated, 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 originals or certified, conformed 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
as we have deemed necessary or appropriate for the purposes of this opinion. We
have

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SPX Corporation                        -2-                       August 28, 2001

examined, among other documents, the Registration Statement and the Indentures.

                  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 or reproduction copies. As
to various questions of fact relevant to the opinions expressed herein, we have
relied upon, and assume the accuracy of, certificates and oral or written
statements and other information of or from representatives of the Company and
others and assume compliance on the part of all parties to the Indentures with
their covenants and agreements contained therein.

                  To the extent it may be relevant to the opinions expressed
below, we have assumed that (i) the Company will have sufficient authorized but
unissued shares of Common Stock on the date of any issuance of shares
registered pursuant to the registration statement and (ii) the Trustee will
have the power and authority to enter into and perform the Indentures and to
consummate the transactions contemplated thereby, that the Indentures will be
duly authorized, executed and delivered by, and will constitute the legal,
valid and binding obligations of, the Trustee, enforceable against the Trustee
in accordance with their terms, and that the Trustee will comply with all of
its obligations under the Indentures and all laws applicable thereto.

                  Based upon the foregoing and subject to the limitations,
qualifications and assumptions set forth herein, we are of the opinion that:

                  1. When (i) the Registration Statement has become effective
under the Securities Act, (ii) the terms of the issuance and sale of the shares
of Common Stock registered pursuant to the Registration Statement have been duly
approved by the Board of Directors of the Company in conformity with the
Company's Certificate of Incorporation (the "Certificate of Incorporation"), and
(iii) such shares are issued and delivered against payment therefor for an
amount in excess of the par value thereof and in accordance with the terms of
the agreement under which they are sold, such shares of Common Stock will be
validly issued, fully paid and non-assessable.

                  2. When (i) the Registration Statement has become effective
under the Securities Act, (ii) the applicable Indenture and any relevant
supplemental indenture is duly executed and delivered by the Company, (iii) the
terms of the Debt Securities and their issue and sale have been duly established
in

<PAGE>   3

SPX Corporation                        -3-                       August 28, 2001

conformity with the applicable Indenture, do not violate any applicable law
or agreement or instrument then binding on the Company and comply with any
requirement or restriction imposed by any court or governmental body having
jurisdiction over the Company and (iv) the Debt Securities have been duly
executed and authenticated in accordance with the terms of the applicable
Indenture and issued and sold as contemplated in the Registration Statement, the
Debt Securities will constitute valid and binding obligations of the Company,
enforceable against the Company in accordance with the terms of the Debt
Securities.

                   We express no opinion as to the enforceability of any
provision of the Indentures (i) providing for indemnification or contribution,
(ii) specifying that provisions thereof may be waived only in writing, to the
extent that an oral agreement or an implied agreement by trade practice or
course of conduct has been created that modifies any provision of the Indentures
or (iii) as to the legality, validity, binding effect or enforceability of any
provision of the Debt Securities or the Indentures providing for payments
thereunder in a currency other than currency of the United States of America to
the extent that a court of competent jurisdiction, under applicable law, will
convert any judgment rendered in such other currency into currency of the United
States of America or to the extent that payment in a currency other than
currency of the United States of America is contrary to applicable law.

                  The opinions set forth above are subject to (i) applicable
bankruptcy, insolvency, reorganization, moratorium, fraudulent conveyance and
other similar laws affecting creditors' rights and remedies generally, and


<PAGE>   4


SPX Corporation                        -4-                       August 28, 2001


(ii) general principles of equity including, without limitation, standards of
materiality, good faith, fair dealing and reasonableness, equitable defenses and
limits as to the availability of equitable remedies, whether such principles are
considered in a proceeding at law or in equity.

                  The opinions expressed herein are limited to the federal laws
of the United States of America, the laws of the State of New York and, to the
extent relevant to the opinions expressed herein, the General Corporation Law of
the State of Delaware (the "DGCL") and applicable provisions of the Delaware
Constitution, in each case as currently in effect, and reported judicial
decisions interpreting the DGCL and such provisions of the Delaware
Constitution. The opinion expressed herein is given as of the date hereof, and
we undertake no obligation to supplement this letter if any applicable laws
change after the date hereof or if we become aware of any facts that might
change the opinion expressed herein after the date hereof or for any other
reason.

                  We hereby consent to the use of our name on the front cover of
the Registration Statement, the filing of this opinion as an exhibit to the
Registration Statement and to the references to this firm under the captions
"Legal Matters" in the prospectus contained in the Registration Statement and
"Legal Matters" in any prospectus supplement forming a part of the Registration
Statement. In giving these consents, we do not hereby admit that we are in the
category of persons whose consent is required under Section 7 of the Securities
Act.

                                    Very truly yours,

                                    FRIED, FRANK, HARRIS, SHRIVER & JACOBSON

                                    By: /s/ Stuart Gelfond



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