Clock gears
Przemek Pietrak
CC BY-SA 3.0
Athens_tram_cable_autotension_pulleys
Badseed
CC BY-SA 4.0
Wheel_on_“Peggy,”_a_Lima_Shay_Geared_Steam_Locomotive_(SN_2172)
Steven Fine
CC-BY-SA 4.0
Industry during the First World War- Bradford Q28523
Lewis G P
IWM Non Commercial Licence
Dorothy_Stevens-Aeroplane_Factory_Ready_for_Shipment
Dorothy Stevens
Public domain
Rods n Wires
Ben Salter from Wales
CC BY-SA 2.0