Document:

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                                                                   Exhibit 10.13
                                                                   -------------

                             AT HOLDINGS CORPORATION
                    1998 SUPPLEMENTAL STOCKHOLDERS AGREEMENT

                  THIS SUPPLEMENTAL STOCKHOLDERS AGREEMENT (this "Agreement"),
dated as of December 17, 1998, is made by and among AT Holdings Corporation, a
Delaware corporation (the "Corporation"), Argo-Tech Corporation, a Delaware
corporation ("Argo-Tech") and Key Trust Company of Ohio, N.A., in its capacity
as Trustee (the "Trustee") under the Argo-Tech Corporation Employee Stock
Ownership Plan and Trust Agreement (the "Argo-Tech ESOP").

                                    RECITALS
                                    --------

                  WHEREAS, the parties hereto believe that it is in the best
interest of the Corporation, Argo-Tech, and the Corporation's stockholders for
the Trustee to join in certain provisions of the Stockholders' Agreement, dated
the date hereof (the "Stockholders Agreement"), to which certain other
stockholders of the Corporation are parties such that the Trustee will receive
certain benefits of such Stockholders Agreement as described herein;

                  NOW, THEREFORE, in consideration of the premises and the terms
herein contained, the parties hereto hereby agree as follows:

                                    AGREEMENT
                                    ---------

                                    SECTION 1

                                   DEFINITIONS
                                   -----------

                  1.1 CERTAIN DEFINITIONS. Unless otherwise defined herein, all
capitalized terms used herein have the meanings given to them in the
Stockholders Agreement.

                                    SECTION 2

                                 TERMINATION OF
                    1994 SUPPLEMENTAL STOCKHOLDERS AGREEMENT
                    ----------------------------------------

                  2.1 TERMINATION. The parties hereto hereby waive all rights
granted under the 1994 Supplemental Stockholders Agreement, as amended and
supplemented to the date hereof, between the Corporation, Argo-Tech and the
Trustee (the "1994 Agreement") and agree that this Agreement supersedes and
replaces such 1994 Agreement in all respects.

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                                    SECTION 3

                       AMENDMENT OF STOCKHOLDERS AGREEMENT
                       -----------------------------------

                  3.1 The Corporation agrees that it will not agree or consent
to any amendment, supplement, modification, alteration, waiver of rights under,
or termination of the Stockholders Agreement, other than by the addition or
deletion of members of the Management Investor group from time to time, without
the written consent of the Trustee, which consent will not be unreasonably
denied or withheld. If the Trustee has not acted upon the Corporation's written
request for such consent and so advised the Corporation within ten (10) business
days of its actual receipt of such a request, the consent of the Trustee shall
not be required as to the individual action as to which consent was requested.

                                    SECTION 4

                                 RIGHTS GRANTED
                                 --------------

                  4.1 RIGHT OF FIRST REFUSAL. The Trustee is entitled to all
rights of, and is subject to all conditions imposed on, an Investor or group of
Investors owning a combined total of ten percent (10%) or more Common Stock
regarding Rights of First Refusal as specifically described in Section 2.2 of
the Stockholders Agreement.

                  4.2 TAG-ALONG RIGHTS. The Trustee is entitled to all rights
of, and is subject to all conditions imposed on, an Investor or group of
Investors owning a combined total of ten percent (10%) or more of the Common
Stock regarding Tag-Along Rights as specifically described in Section 2.3 of the
Stockholders Agreement.

                  4.3 REGISTRATION RIGHTS. As of the date hereof, the Company
and the Trustee will have entered into the Registration Rights Agreement, by and
among the Trustee and all parties to the Stockholders Agreement in the form
attached as ANNEX 2 to the Stockholders Agreement.

                                    SECTION 5

                                  MISCELLANEOUS
                                  -------------

                  5.1 GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF DELAWARE, WITHOUT GIVING
EFFECT TO PRINCIPLES OF CONFLICTS OF LAW.

                  5.2 COUNTERPARTS. This Agreement may be executed
simultaneously in any number of counterparts, each of which when so executed and
delivered shall be taken to be an original; but such counterparts shall together
constitute one and the same document.

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                  5.3 NOTICES AND DEMANDS. Any notice or demand which is
required or provided to be given under this Agreement shall be deemed to have
been sufficiently given and received for all purposes when delivered by hand,
telecopy, telex or other method of facsimile, or five days after being sent by
certified or registered mail, postage and charges prepaid, return receipt
requested, or two days after being sent by overnight delivery providing receipt
of delivery, to the following addresses:

                           if to the Corporation:

                           c/o Argo-Tech Corporation
                           23555 Euclid Avenue
                           Cleveland, Ohio  44117-1795
                           Attn: Michael S. Lipscomb
                           Phone: 216/692-6000
                           Fax: 216/692-6331

                           with a copy to:

                           Jones, Day, Reavis & Pogue
                           North Point
                           901 Lakeside Avenue
                           Cleveland, Ohio  44114
                           Attn: David P. Porter
                           Phone: 216/586-7215
                           Fax: 216/579-0212

                           if to the Trustee:

                           Key Trust Company of Ohio, N.A.
                           127 Public Square
                           Cleveland, Ohio  44114
                           Attn: Richard Lutts
                           Phone: 216/689-7531
                           Fax: 216/689-7548

                           with a copy to:

                           Calfee, Halter & Griswold LLP
                           800 Superior Avenue
                           Cleveland, Ohio  44114
                           Attn: Thomas A. Jorgensen
                           Phone: 216/622-8443
                           Fax: 216/241-0816

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                  5.4 TERM. The term of this Agreement shall commence as of the
date hereof and shall terminate upon the first to occur of the following events:

                      (a)   An initial public offering by the Corporation
                            resulting in at least $30,000,000 of gross proceeds,
                            without the deduction of fees, discounts and
                            expenses; or

                      (b)   the Investors, in the aggregate, own less than
                            thirty percent (30%) (by voting power or by value of
                            the then outstanding Common Stock.)

                  5.5 FEES AND EXPENSES. The Corporation shall reimburse the
Trustee for the reasonable out-of-pocket expenses incurred by the Trustee in
connection with the transactions contemplated by this Agreement.

                  IN WITNESS WHEREOF, the parties hereto have caused this
Agreement to be duly executed and delivered as of the day and year first above
written.

                                            AT HOLDINGS CORPORATION

                                            By:_________________________________
                                               Name:
                                               Title:

                                            ARGO-TECH CORPORATION

                                            By:_________________________________
                                               Name:
                                               Title:

                                            KEYTRUST COMPANY OF OHIO, N.A., in
                                             its Capacity as Trustee under the
                                             Argo-Tech Corporation Employee
                                             Stock Ownership Plan and Trust
                                             Agreement

                                            By:_________________________________
                                               Name:
                                               Title:

                                            By:_________________________________
                                               Name:
                                               Title:

                                        4<PAGE>   1
                                                                   Exhibit 10.29

                             AT HOLDINGS CORPORATION

                               1998 INCENTIVE PLAN

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                            AT HOLDINGS CORPORATION

                              1998 Incentive Plan
                              -------------------

                  1. AT Holdings Corporation, a Delaware corporation (the
"Company"), and Argo-Tech Corporation, a Delaware corporation ("Argo-Tech
Corporation"), hereby establish the AT Holdings Corporation 1998 Incentive Plan
(the "Plan"). The total number of shares that may be issued and sold under
options granted pursuant to the Plan will not exceed 100,000 shares of the
Common Stock of the Company, par value $.001 per share ("Common Stock"), except
to the extent of adjustments authorized by Paragraph 5 of the Plan. Such shares
of Common Stock may be treasury shares, shares of original issue, shares held by
Argo-Tech Corporation or a combination of the foregoing. If an option is
canceled without exercise, the Company may award additional options for the
number of shares of Common Stock reflected by the canceled option.

                  2. The Board of Directors of the Company (the "Board") or the
Compensation Committee thereof (the "Compensation Committee") may, from time to
time and upon such terms and conditions as it may determine, authorize the grant
to officers (including officers who are members of the Board of Directors) and
to other key employees of the Company or any of its Subsidiaries of options to
buy from the Company shares of Common Stock and may fix the number of shares to
be covered by each such option; provided, however, that the maximum number of
shares with respect to which options may be granted to the same individual under
the Plan may not exceed, in the aggregate, 50,000 shares, except to the extent
of adjustments authorized by Paragraph 5 of the Plan. Successive options may be
granted to the same individual whether or not the option or options first
granted to such individual remain unexercised.

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                  3. Options granted under the Plan may be (a) options that are
intended to qualify under particular provisions of the Internal Revenue Code of
1986, as amended (the "Code"), (b) options that are not intended so to qualify
under the Code, or (c) combinations of the foregoing. No option shall run for
more than ten years from the date granted. No option may be transferable by the
optionee otherwise than by will or the laws of descent and distribution. Options
exercised during the optionee's lifetime will be exercisable only by the
optionee or the optionee's guardian or legal representative.

                  4. The exercise prices for options may be more than, less
than, or equal to the fair market value of the shares covered by the option, as
the Board or the Compensation Committee may determine at the time of grant. The
exercise price for any shares is payable (a) in cash or by check, (b) if
authorized by the Board or the Compensation Committee at the time of exercise by
delivery to the Company of a promissory note or notes of the optionee payable
over not more than five years and with such other terms as the Board or the
Compensation Committee may determine from time to time, (c) by the actual or
constructive transfer to the Company of Mature Shares, or (d) by a combination
of such methods of payment.

                  5. The Board or the Compensation Committee may make or provide
for such adjustments in the option price and in the number or kind of shares of
the Company's Common Stock or other securities covered by outstanding options as
such Board or Committee may determine is equitably required to prevent dilution
or enlargement of the rights of optionees that would otherwise result from (i)
any increase or decrease in the number or change in the kind of shares of
capital stock of the Company by reason of a stock dividend, stock split, reverse
stock split, recapitalization, spin-off or other such increase or decrease or
change effected without the receipt of consideration by the Company, or (ii) any
consolidation or merger or other

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reorganization, or (iii) any distribution of rights or warrants to purchase
stock to all holders of the Company's common stock, or (iv) any other corporate
transaction or event having an effect similar to any of the foregoing. Moreover,
in the event of any such transaction or event, the Board or the Compensation
Committee, in its discretion, may provide in substitution for any or all
outstanding awards under the Plan such alternative consideration as it, in good
faith, may determine to be equitable in the circumstances and may require in
connection therewith the surrender of all awards so replaced. The Board or the
Compensation Committee may also make or provide for such adjustments in the
number or kind of shares of the Company's Common Stock or other securities that
may be sold under the Plan as such Board or Committee may determine is
appropriate to reflect any transaction or event described in the preceding
sentence.

                  6. An option granted under the Plan will, upon the occurrence
of a Sale Transaction, become exercisable in full as to any then unvested shares
immediately prior to the consummation of such Sale Transaction.

                  7. The form of any Stock Option Agreement will be prescribed
by the Board or the Compensation Committee, and the terms of any Stock Option
Agreement evidencing an outstanding option may, with the concurrence of the
affected optionee, be amended or modified by the Board or the Compensation
Committee, provided that the terms and conditions of each such Stock Option
Agreement and amendment are not inconsistent with the Plan.

                  8. The Board or the Compensation Committee may, with the
concurrence of the affected optionee, cancel any option granted under the Plan.
In the event of any such cancellation, the Board or the Compensation Committee
may authorize the granting of new options (which may or may not cover the same
number of shares of Common Stock which had been the subject of any prior option)
in such manner, at such option price and subject to the same

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terms, conditions and discretions as, under the Plan, would have been applicable
had the canceled options not been granted.

                  9. The Plan may be amended from time to time by the Board or
the Compensation Committee but without further approval by the shareholders of
the Company no such amendment may increase the aggregate number of shares of
Common Stock that may be issued and sold under the Plan (except that adjustments
authorized by Paragraph 5 shall not be limited by this provision) or change the
designation in Paragraph 2 of the class of employees eligible to receive options
or, to the extent Rule 16b-3 under the Securities Exchange Act of 1934 (or any
successor rule to the same effect) is then applicable to the Plan, cause such
Rule to no longer be applicable to the Plan.

                  10. As used herein, the following capitalized terms have
meanings as set forth below.

                  "Mature Shares" means (a) nonforfeitable, unrestricted shares
of Common Stock that have been owned by the optionee for more than six (6)
months prior to the date of exercise or (b) such other Company securities as the
Company's chief accounting officer, upon consultation with the Company's
independent accountants, determines the acceptance of which by the Company will
not adversely affect the Company's tax or accounting position.

                  "Person" means any corporation, partnership, association,
firm, entity or individual(s).

                  "Sale Transaction" means (a) the sale, transfer or other
disposition of all or substantially all of the assets of the Company, except a
sale, transfer or disposition (i) to a Subsidiary of the Company or (ii) that
results in the holders of the then-outstanding securities of the Company
generally eligible to vote in the election of directors of the Company
possessing, in

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the aggregate, a majority ownership interest in the Person acquiring such
assets, (b) any transaction resulting in a majority of the then-outstanding
securities of the Company generally eligible to vote in the election of
directors of the Company being held or owned beneficially by one Person or an
affiliated group of Persons, (c) a merger or consolidation of the Company with
another Person, except a merger or consolidation of the Company (i) with a
Subsidiary of the Company (in which event such Subsidiary, if the surviving
corporation, will be deemed thereafter to be the Company for purposes of this
definition) or (ii) that results in the holders of the then-outstanding
securities of the Company generally eligible to vote in the election of
directors of the Company possessing, in the aggregate, a majority ownership
interest in the surviving Person, or (d) the voluntary liquidation or
dissolution of the Company.

                  "Subsidiary" means any corporation (other than the Company) in
an unbroken chain of corporations beginning with the Company if each of the
corporations (or a group of corporations that themselves are Subsidiaries) other
than the last corporation in the unbroken chain owns stock possessing fifty
percent or more of the total combined voting power of all classes of stock in
one of the other corporations in such chain.

                  11. No option may be granted under the Plan after December 31,
2007.

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