<PAGE>

                                                                     Exhibit 4.2


               FIRST SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"),
dated as of December 22, 2005, between D-R Steam LLC (the "New Guarantor"), a
subsidiary of Dresser-Rand Group Inc., a Delaware corporation (the "Company"),
the existing Guarantors listed on the signature page to the Indenture (as
defined below) (the "Existing Guarantors") and Citibank, N.A., as trustee under
the Indenture referred to below (the "Trustee").


                              W I T N E S S E T H :


               WHEREAS, the Company and the Existing Guarantors have heretofore
executed and delivered to the Trustee an indenture (as amended, supplemented or
otherwise modified, the "Indenture"), dated as of October 29, 2004, providing
for the issuance of 7?% Senior Subordinated Notes due 2014 (the "Notes");

               WHEREAS, Section 4.17 of the Indenture provides that under
certain circumstances the New Guarantor shall execute and deliver to the Trustee
a supplemental indenture pursuant to which the New Guarantor shall
unconditionally guarantee all of the Company's Obligations under the Notes and
the Indenture on the terms and conditions set forth herein (the "Note
Guarantee"); and

               WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee,
the Company and the Existing Guarantors are authorized to execute and deliver
this Supplemental Indenture.


               NOW THEREFORE, in consideration of the foregoing and for other
good and valuable consideration, the receipt of which is hereby acknowledged,
the New Guarantor, the Company and the Trustee mutually covenant and agree for
the equal and ratable benefit of the Holders of the Notes as follows:


               1. DEFINED TERMS. Defined terms used herein without definition
shall have the meanings assigned to them in the Indenture.

               2. AGREEMENT TO INDENTURE. The New Guarantor hereby agrees,
jointly and severally with all Existing Guarantors, to provide an unconditional
guarantee on the terms and subject to the conditions set forth in Article 11 of
the Indenture and to be bound by all other applicable provisions of the
Indenture, including the provisions relating to the subordination of such
guarantee set forth in Article 11, and the Notes and to perform all of the
obligations and agreements of a Guarantor under the Indenture.

               3. NO RECOURSE AGAINST OTHERS. No past, present or future
director, manager, officer, employee, incorporator, stockholder or member of the
Company, any parent entity of the Company or any Subsidiary, as such, will have
any liability for any obligations of the Company or the Guarantors under the
Notes, this Indenture, the Note Guarantees or for any claim based on, in respect
of, or by reason of, such obligations or their creation. Each Holder by
accepting a Note waives and releases all such liability. The waiver and release
are part of the consideration for issuance of the Notes. The waiver may not be
effective to waive liabilities under the federal securities laws.



<PAGE>

               4. NOTICES. All notices or other communications to the New
Guarantor shall be given as provided in Section 13.02 of the Indenture.

               5. RATIFICATION OF INDENTURE; SUPPLEMENTAL INDENTURES PART OF
INDENTURE. Except as expressly amended hereby, the Indenture is in all respects
ratified and confirmed and all the terms, conditions and provisions thereof
shall remain in full force and effect. This Supplemental Indenture shall form a
part of the Indenture for all purposes, and every holder of Notes heretofore or
hereafter authenticated and delivered shall be bound hereby.

               6. GOVERNING LAW. THIS INDENTURE, THE NOTES AND THE NOTE
GUARANTEE SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF
THE STATE OF NEW YORK.

               7. COUNTERPARTS. The parties may sign any number of copies of
this Supplemental Indenture. Each signed copy shall be an original, but all of
them together represent the same agreement.

               8. EFFECT OF HEADINGS. The Section headings herein are for
convenience only and shall not effect the construction thereof.

               9. TRUSTEE MAKES NO REPRESENTATION. The Trustee makes no
representation as to the validity or sufficiency of this Supplemental Indenture.



<PAGE>


               IN WITNESS WHEREOF, the parties hereto have caused this
Supplemental Indenture to be duly executed and attested, all as of the date
first above written.

Dated: December 22, 2005


DRESSER-RAND GROUP LLC                  D-R STEAM LLC

By: /s/ Elizabeth C. Powers             By: /s/ Elizabeth C. Powers
    ---------------------------------      ---------------------------------
Name:   Elizabeth C. Powers             Name:   Elizabeth C. Powers
Title:  Vice President and Chief        Title:  Vice President -- Treasurer
          Administrative Officer

                                        CITIBANK, N.A.
DRESSER-RAND LLC                              as Trustee

By: /s/ Elizabeth C. Powers             By: /s/ Louis Piscitelli
    ---------------------------------       --------------------------------
Name:   Elizabeth C. Powers             Name:   Louis Piscitelli
Title:  Secretary                       Title:  Vice President


DRESSER-RAND POWER LLC

By: /s/ B.W. Dickson
    ---------------------------------
Name:   B.W. Dickson
Title:  President


DRESSER-RAND COMPANY


By: /s/ Elizabeth C. Powers
    ---------------------------------
Name:   Elizabeth C. Powers
Title:  Secretary


DRESSER-RAND GLOBAL SERVICES, LLC


By: /s/ Talbot A. Lancaster
    ---------------------------------
Name:   Talbot A. Lancaster
Title:  Vice President Treasurer