Portais gerais para equipamento, Tech library, software, bibliografia, links a empresas que fabricam os produtos...
https://sdp-si.com/
http://mdmetric.com/
http://www.gearhob.com/
http://www.diracdelta.co.uk/
http://www.globalspec.com/
http://www.machinedesign.com/
http://www.amidata.es
http://www.engineersedge.com/
http://www.ien-online.com
http://www.thomasglobal.com

Fadiga
http://www.fatiguecalculator.com/

Engineering fundamentals
http://www.efunda.com

Propriedades de materiais (ver sites de organizações de fabricantes)
http://www.matweb.com
http://www.ductile.org/

Rolamentos
http://www.fag.com
http://www.skf.com/

Correias
http://www.contitech.de/
http://www.optibelt.de
http://www.fennerdrives.com

Correntes
http://chain-guide.com/
http://www.flexon.de/
http://www.renold.com.au/
http://tsubakimoto.com/

Embraiagens
http://www.formsprag.com

Engrenagens
http://www.qtcgears.com/
http://www.formsprag.com
http://www.flender.com/

Transmissões
http://www.fennerdrives.com
http://www.powertransmission.com/

Soldadura
http://www.gowelding.com/

Lubrificantes
http://www.klueber.com/

Parafusos
http://www.gewinde-normen.de/en/index.html

Uniões
http://www.renold.com.au/