機器
abstract
aluminum
auto
automobile
background
black
box
business
car
closeup
cnc
cooperation
coupling
crank
crankshaft
engine
engineering
equipment
friction
gear
gearbox
gearing
geometrical
geometry
heavy
industrial
industry
inside
iron
manufacture
manufacturing
mechanical
metal
metallic
motor
part
parts
pinion
shaft
shiny
steel
strength
technical
technology
teeth
template
transmission
vehicle
white