резервна система
back-to-back circuit
back-to-back connection
back-to-back radio stations
back-to-back relay
back-up hydraulic system
back-up hydraulic system failure indicator
fire extinguishing system sprinkler system and fire alarm system
back-up fire control
cut back co-operation
I read back
play back kit
pull back
push back
read back
reverse engineering ( back- wards engineering)
Camel-back water pouch
Field Pack, Air Support Back
back brief / backbrief
peel back
back on the block
back-up circuit breaker
armor back plate
back bearing housing
back blow
back contact
back cushion
back fork
back gun
back impact
back kick
back lamp
back lash