-----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,
 TctIiC90oCDRVrpXhTpQizifa2+RHWe3IWU5aMBZTgrrz+xdUZO6HvMVAl2enDKv
 q9aNLhbcbXlGWSynpCFbiA==

<SEC-DOCUMENT>0000740761-05-000047.txt : 20051213
<SEC-HEADER>0000740761-05-000047.hdr.sgml : 20051213
<ACCEPTANCE-DATETIME>20051213163946
ACCESSION NUMBER:		0000740761-05-000047
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20051209
FILED AS OF DATE:		20051213
DATE AS OF CHANGE:		20051213

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Korthals Robert W
		CENTRAL INDEX KEY:			0001297863

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50858
		FILM NUMBER:		051261383

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		416-982-8341

	MAIL ADDRESS:	
		STREET 1:		77 KING STREET WEST, SUITE 4545
		STREET 2:		ROYAL TRUST TOWER, PO BOX 298
		CITY:			TORONTO
		STATE:			A6
		ZIP:			M5K 1K2

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>2005-12-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001297863</rptOwnerCik>
            <rptOwnerName>Korthals Robert W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>77 KING STREET WEST, SUITE 4545</rptOwnerStreet1>
            <rptOwnerStreet2>ROYAL TRUST TOWER, PO BOX 298</rptOwnerStreet2>
            <rptOwnerCity>TORONTO</rptOwnerCity>
            <rptOwnerState>A6</rptOwnerState>
            <rptOwnerZipCode>M5K 1K2</rptOwnerZipCode>
            <rptOwnerStateDescription>ONTARIO, CANADA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock, Par Value $0.01 Per Share</value>
            </securityTitle>
            <transactionDate>
                <value>2005-12-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>129</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>48.24</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2708</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>2005-12-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>52</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>47.41</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2760</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>Robert W. Korthals</signatureName>
        <signatureDate>2005-12-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----