<Page>
Exhibit 5.1
[LATHAM WATKINS LETTERHEAD]
April 17, 2003
Rexnord Corporation
and each co-registrant to
Registration Statement No. 333-102428
4701 Greenfield Avenue
Milwaukee, WI 53214
Re: REGISTRATION STATEMENT ON FORM S-4 (NO. 333-102428) RELATING TO
$225,000,000 AGGREGATE PRINCIPAL AMOUNT OF 10 1/8% SENIOR
SUBORDINATED NOTES DUE 2012
Ladies and Gentlemen:
In connection with the registration of $225,000,000 aggregate principal
amount of 10 1/8% Senior Subordinated Notes due 2012 (the "Securities") by
Rexnord Corporation, a Delaware corporation (the "Company') and each
co-registrant thereto, and the guarantees of the Securities (the
"Guarantees") by each of the entities listed on Schedule A hereto (the
"Guarantors"), under the Securities Act of 1933, as amended (the "Act"), on
Form S-4 filed with the Securities and Exchange Commission (the "Commission")
on January 9, 2003 (File No. 333-102428), (the "Registration Statement"), you
have requested our opinion with respect to the matters set forth below. The
Securities and the Guarantees will be issued pursuant to an indenture dated
as of November 25, 2002 (the "Indenture") by and among the Company, each of
the Guarantors and Wells Fargo Bank Minnesota, National Association, as
Trustee (the "Trustee"). The Securities and the Guarantees will be issued in
exchange for the Company's outstanding 10 1/8% Senior Subordinated Notes due
2012 on the terms set forth in the prospectus contained in the Registration
Statement and the Letter of Transmittal filed as an exhibit thereto. The
Indenture, the Securities and the Guarantees are sometimes referred to herein
collectively as the "Operative Documents." Capitalized terms used herein
without definition have the meanings assigned to them in the Indenture.
In our capacity as your special counsel in connection with such
registration, we are familiar with the proceedings taken by the Company and each
of the Guarantors incorporated in the State of Delaware or the State of New York
(the "Covered Guarantors") in connection with the authorization and issuance of
the Securities and the Guarantees, respectively. In addition, we have made such
legal and factual examinations and inquiries, including an examination of
originals or copies certified or otherwise identified to our satisfaction of
such documents, corporate records and instruments, as we have deemed necessary
or appropriate for purposes of this opinion.
In our examination, we have assumed the genuineness of all signatures,
the authenticity of all documents submitted to us as originals, and the
conformity to authentic original documents of all documents submitted to us as
copies.
<Page>
We are opining herein as to the effect on the subject transaction only
of the federal laws of the United States, the internal laws of the State of New
York and the General Corporation Law of the State of Delaware, and we express no
opinion with respect to the applicability thereto, or the effect thereon, of the
laws of any other jurisdiction or, in the case of the State of Delaware, any
other laws, or as to any matters of municipal law or the laws of any local
agencies within any state. Various issues concerning the laws of the States of
Louisiana, Nebraska, Nevada and Wisconsin are addressed in the respective
opinions of the law firms listed on Schedule B hereto, separately provided to
you, and we express no opinion with respect to those matters.
Subject to the foregoing and the other matters set forth herein, it is
our opinion that as of the date hereof:
(1) The Securities have been duly authorized by all necessary corporate
action of the Company, and when executed, authenticated and delivered
by or on behalf of the Company against payment therefor in accordance
with the terms of the Indenture, will constitute the legally valid and
binding obligations of the Company, enforceable against the Company in
accordance with their terms.
(2) Each of the Guarantees to be executed and delivered by each of the
Covered Guarantors has been duly authorized by all necessary corporate
action of the respective Covered Guarantor, and when executed in
accordance with the terms of the Indenture and upon due execution,
authentication and delivery of the Securities and upon payment
therefor, each of the Guarantees will be the legally valid and binding
obligation of the respective Guarantor, enforceable against the
respective Guarantor in accordance with its terms.
The opinions rendered in the foregoing paragraphs relating to the
enforceability of the Securities and the Guarantees are subject to the following
exceptions, limitations and qualifications: (i) the effect of bankruptcy,
insolvency, reorganization, fraudulent transfer, moratorium or other similar
laws now or hereafter in effect relating to or affecting the rights and remedies
of creditors; (ii) the effect of general principles of equity, whether
enforcement is considered in a proceeding in equity or law, and the discretion
of the court before which any proceeding therefor may be brought; and (iii) the
unenforceability under certain circumstances under law or court decisions of
provisions for the indemnification of or contribution to a party with respect to
a liability where such indemnification or contribution is contrary to public
policy.
To the extent that the obligations of the Company and the Guarantors
under the Operative Documents may be dependent upon such matters, we assume for
purposes of this opinion that: (i) the Trustee and each Guarantor that is not a
Covered Guarantor (a) is duly organized, validly existing and in good standing
under the laws of its jurisdiction of organization; (b) has the requisite
organizational and legal power and authority to perform its obligations under
each of the Operative Documents to which it is
2
<Page>
a party; (c) is duly qualified to engage in the activities contemplated by each
such Operative Document; (d) has duly authorized, executed and delivered each
such Operative Document; and (ii) with respect to the Trustee, each Operative
Document to which it is a party constitutes its legally valid and binding
agreement, enforceable against it in accordance with its terms.
We consent to your filing this opinion as an exhibit to the
Registration Statement and to the reference to our firm contained under the
heading "Legal Matters" contained in the prospectus contained therein.
Very truly yours,
/s/ Latham & Watkins LLP
3
<Page>
SCHEDULE A
NAME JURISDICTION
---- ------------
1. PT Components Inc. Delaware
2. RAC-I Inc. Delaware
3. RBS Acquisition Corporation Delaware
4. RBS China Holdings L.L.C. Delaware
5. RBS Global Inc. Delaware
6. RBS North America Inc. Delaware
7. Rexnord Germany-1 Inc. Delaware
8. Rexnord International Inc. Delaware
9. Rexnord Industries, Inc. Delaware
10. Winfred Berg Licensco Inc. Delaware
11. W.M. Berg Inc. Delaware
12. Prager Incorporated Louisiana
13. Addax Inc. Nebraska
14. Clarkson Industries Inc. New York
15. Rexnord Ltd. Nevada
16. Rexnord Puerto Rico Inc. Nevada
17. Betzdorf Chain Co. Inc. Wisconsin
4
<Page>
SCHEDULE B
<Table>
<Caption>
- --------------------------------------------------------------------------------------------
STATE REXNORD ENTITY FIRM
- --------------------------------------------------------------------------------------------
NEBRASKA Addax, Inc. Fitzgerald, Schorr, Barmettler &
Brennan, P.C., L.L.O.
13220 California Street, Suite 400
Omaha, Nebraska 68154
- --------------------------------------------------------------------------------------------
LOUISIANA Prager Incorporated Sher, Garner, Cahill, Richter, Klein,
McAllister and Hilbert L.L.C.
909 Poydras Street
Twenty Eighth Floor
New Orleans, LA 70112
- --------------------------------------------------------------------------------------------
NEVADA Rexnord Ltd. Hale Lane Peek Dennison and Howard
Rexnord Puerto Rico Inc. 100 West Liberty Street, Tenth Floor,
P.O. Box 3237, Reno, Nevada 89505
- --------------------------------------------------------------------------------------------
WISCONSIN Betzdorf Chain Company Inc. Quarles & Brady
411 East Wisconsin Avenue Suite 2040
Milwaukee, Wisconsin 53202-4497
(414) 277-5651
- --------------------------------------------------------------------------------------------
</Table>