-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 HdMyxwh90gVRK3dYv8f/pbCS5olPklZcmsc4fWLScAFSafzZRWrb9eMDpHm68pnM
 Tmg70g2E5fM6WMNU2kCLKw==

<SEC-DOCUMENT>0001355892-07-000001.txt : 20070129
<SEC-HEADER>0001355892-07-000001.hdr.sgml : 20070129
<ACCEPTANCE-DATETIME>20070129173433
ACCESSION NUMBER:		0001355892-07-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20070126
FILED AS OF DATE:		20070129
DATE AS OF CHANGE:		20070129

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Fulton Tricia L
		CENTRAL INDEX KEY:			0001355892

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21835
		FILM NUMBER:		07562117

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		9413621232

	MAIL ADDRESS:	
		STREET 1:		1500 WEST UNIVERSITY PARKWAY
		CITY:			SARASOTA
		STATE:			FL
		ZIP:			34243

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SUN HYDRAULICS CORP
		CENTRAL INDEX KEY:			0001024795
		STANDARD INDUSTRIAL CLASSIFICATION:	MISCELLANEOUS FABRICATED METAL PRODUCTS [3490]
		IRS NUMBER:				592754337
		STATE OF INCORPORATION:			FL
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1500 WEST UNIVERSITY PKWY
		CITY:			SARASOTA
		STATE:			FL
		ZIP:			34243
		BUSINESS PHONE:		9413621200

	MAIL ADDRESS:	
		STREET 1:		1500 WEST UNIVERSITY PKWY
		CITY:			SARASOTA
		STATE:			FL
		ZIP:			34243
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-01-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001024795</issuerCik>
        <issuerName>SUN HYDRAULICS CORP</issuerName>
        <issuerTradingSymbol>SNHY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001355892</rptOwnerCik>
            <rptOwnerName>Fulton Tricia L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1500 WEST UNIVERSITY PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SARASOTA</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>34243</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2007-01-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>21.35</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7935</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1279</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>BY ESOP TRUST</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 29, 2006.</footnote>
        <footnote id="F2">Includes an additional 192 shares purchased through the Sun Hydraulics Corporation Employee Stock Purchase Plan.</footnote>
        <footnote id="F3">Reflects allocations of shares under the Sun Hydraulics Corporation Employee Stock Ownership Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Gregory C. Yadley, as Attorney-in-Fact for TRICIA L. FULTON</signatureName>
        <signatureDate>2007-01-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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