-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 bcQKapl2IU/AYJKw19WAYw==

<SEC-DOCUMENT>0000740761-06-000001.txt : 20060105
<SEC-HEADER>0000740761-06-000001.hdr.sgml : 20060105
<ACCEPTANCE-DATETIME>20060105125930
ACCESSION NUMBER:		0000740761-06-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060104
FILED AS OF DATE:		20060105
DATE AS OF CHANGE:		20060105

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Mackus Craig R
		CENTRAL INDEX KEY:			0001297859

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50858
		FILM NUMBER:		06511557

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		414-768-4000

	MAIL ADDRESS:	
		STREET 1:		PO BOX 500
		STREET 2:		1100 MILWAUKEE AVENUE
		CITY:			SOUTH MILWAUKEE
		STATE:			WI
		ZIP:			53172

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BUCYRUS INTERNATIONAL INC
		CENTRAL INDEX KEY:			0000740761
		STANDARD INDUSTRIAL CLASSIFICATION:	MINING MACHINERY & EQUIP (NO OIL & GAS FIELD MACH & EQUIP) [3532]
		IRS NUMBER:				390188050
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		P O BOX 500
		STREET 2:		1100 MILWAUKEE AVENUE
		CITY:			SOUTH MILWAUKEE
		STATE:			WI
		ZIP:			53172-0500
		BUSINESS PHONE:		4147684000

	MAIL ADDRESS:	
		STREET 1:		P O BOX 500
		STREET 2:		1100 MILWAUKEE AVENUE
		CITY:			SOUTH MILWAUKEE
		STATE:			WI
		ZIP:			53172-0500

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BUCYRUS ERIE CO /DE
		DATE OF NAME CHANGE:	19920703

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BECOR WESTERN INC/DE
		DATE OF NAME CHANGE:	19860901
</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>2006-01-04</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000740761</issuerCik>
        <issuerName>BUCYRUS INTERNATIONAL INC</issuerName>
        <issuerTradingSymbol>BUCY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001297859</rptOwnerCik>
            <rptOwnerName>Mackus Craig R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>PO BOX 500</rptOwnerStreet1>
            <rptOwnerStreet2>1100 MILWAUKEE AVENUE</rptOwnerStreet2>
            <rptOwnerCity>SOUTH MILWAUKEE</rptOwnerCity>
            <rptOwnerState>WI</rptOwnerState>
            <rptOwnerZipCode>53172</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CFO, Controller and Secretary</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock, Par Value $0.01 Per Share</value>
            </securityTitle>
            <transactionDate>
                <value>2006-01-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>21408</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.125</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>21408</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock, Par Value $0.01 Per Share</value>
            </securityTitle>
            <transactionDate>
                <value>2006-01-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>21408</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>54.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Employee Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.125</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-01-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>21408</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.125</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2004-07-28</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2011-08-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>21408</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>42816</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">100% vested on July 28, 2004 with the IPO</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Craig R. Mackus</signatureName>
        <signatureDate>2006-01-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----