機器
agricultural
antique
closeup
cog
cogwheel
drive
engine
engineering
equipment
force
gear
gearing
gears
grease
green
grinding
historic
historical
industrial
industry
iron
isolated
machinery
mechanical
mechanics
mechanism
mechanisms
metal
old
part
power
precision
quality control
reduction
robust
rust
shaft
spring
steel
sturdy
support
technical
technology
transmission
wheel
workplace
workshop
worm