<SEC-DOCUMENT>0000098362-16-000087.txt : 20160216
<SEC-HEADER>0000098362-16-000087.hdr.sgml : 20160215
<ACCEPTANCE-DATETIME>20160216084416
ACCESSION NUMBER:		0000098362-16-000087
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20160211
FILED AS OF DATE:		20160216
DATE AS OF CHANGE:		20160216

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			TIMKEN CO
		CENTRAL INDEX KEY:			0000098362
		STANDARD INDUSTRIAL CLASSIFICATION:	BALL & ROLLER BEARINGS [3562]
		IRS NUMBER:				340577130
		STATE OF INCORPORATION:			OH
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1835 DUEBER AVE SW
		CITY:			CANTON
		STATE:			OH
		ZIP:			44706-2798
		BUSINESS PHONE:		3304713078

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	TIMKEN ROLLER BEARING CO
		DATE OF NAME CHANGE:	19710304

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Coughlin Christopher A
		CENTRAL INDEX KEY:			0001508035

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-01169
		FILM NUMBER:		161423366

	MAIL ADDRESS:	
		STREET 1:		1835 DUEBER AVE SW
		CITY:			CANTON
		STATE:			OH
		ZIP:			44706
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_145563024342598.xml
<DESCRIPTION>FORM 4
<TEXT>
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    <periodOfReport>2016-02-11</periodOfReport>

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    <issuer>
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        <issuerName>TIMKEN CO</issuerName>
        <issuerTradingSymbol>TKR</issuerTradingSymbol>
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            <rptOwnerCik>0001508035</rptOwnerCik>
            <rptOwnerName>Coughlin Christopher A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4500 MT. PLEASANT ST. NW</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NORTH CANTON</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44720</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP &amp; Group President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

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                    <value>4165</value>
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        <nonDerivativeTransaction>
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                <value>Common Stock</value>
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                <transactionCode>F</transactionCode>
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            <securityTitle>
                <value>Common Stock</value>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17767</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
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                <natureOfOwnership>
                    <value>401(k)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>27.75</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2016-02-11</value>
            </transactionDate>
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                <transactionFormType>4</transactionFormType>
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                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>57475</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2017-02-11</value>
                <footnoteId id="F6"/>
            </exerciseDate>
            <expirationDate>
                <value>2026-02-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>57475.0</value>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Share Unit</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0</value>
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            <transactionDate>
                <value>2016-02-11</value>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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                    <value>22425</value>
                </transactionShares>
                <transactionPricePerShare>
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                <value>2018-12-31</value>
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                <sharesOwnedFollowingTransaction>
                    <value>22425</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Share Unit</value>
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                <value>0.0</value>
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                <value>2016-02-11</value>
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                <value>2020-02-11</value>
            </expirationDate>
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    </derivativeTable>

    <footnotes>
        <footnote id="F1">Reflects shares awarded pursuant to the second half of the 2013-2015 performance cycle for the strategic performance shares granted on February 7, 2013.</footnote>
        <footnote id="F2">Includes 680 shares earned through dividend reinvestment in 2015.</footnote>
        <footnote id="F3">Shares withheld for taxes on 4,165 shares granted from vesting of February 7, 2013 performance share unit grant.</footnote>
        <footnote id="F4">Represents vesting of 25% of the restricted share units granted on February 12, 2015.</footnote>
        <footnote id="F5">Shares withheld for taxes on 1,600 shares granted from vesting of February 12, 2015 restricted share unit grant.</footnote>
        <footnote id="F6">These options will become exercisable in annual 25 percent increments beginning on February 11, 2017.</footnote>
        <footnote id="F7">Performance based restricted stock units subject to certain performance criteria between January 1, 2016 and December 31, 2018.</footnote>
        <footnote id="F8">Grant of 8,975 restricted stock units that vest 25% per year.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Christopher A. Coughlin</signatureName>
        <signatureDate>2016-02-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
