190105d flashcards
Trailer Service Lines
-Carries service air pressure from the tractor (from dual circuit valve or trailer hand valve) to apply trailer service brakes.
-If the trailer service line is separated, air is only lost when a brake application is made
Trailer Supply Line
- The trailer supply line carry supply air from the tractor service reservoirs (through the trailer supply and tractor protection valve) to charge the trailer reservoir
-Supply line separates, trailer emergency brakes automatically apply.
-Air pressure falls below 50psi trailer supply valve pops out and closes leak
-tractor protection valve closes off the service line and warning lights warn operator of low pressure.
Relay Emergency Valve (Charging)
-acts as relay valve to apply, release and regulate braking pressure to the trailer service brakes.
-emergency application of brakes in even of decoupling of trailers.
Dynamiting brakes
directing full trailer/tractor reservoir pressure to brake chambers.
Releasing brakes
only when supply line is restored to at least 60 PSI, or air pressure is drained from the trailer reservoir.
Pre CMVSS & CMVSS 121
prior to 1975(pre) anything after is cmvss121 brake systems
Trailer spring brake valve
automatically applies spring brakes in supply line failure**
-prevents compounding
-
Trailer Spring brake control valve (SR-5)
-acts as a relay and quick release valve for the spring brakes
-prevents compounding
-prioritizes spring brake release over filling reservoirs
-allows for faster spring brake release by using store service air
-automatically applies spring brakes when supply pressure is lost
SR-5 check valves
B- maintains pressure
sr-5 pressure protection valve
opens and closes to maintain 85psi supply pressure not allowing spring brakes to automatically apply
Shut off Valve
operate towing vehicle as single unit, supply line must be shut off to prevent escape of supply air from glad hands
Quick Release
air exhausted at back of trailer instead of flowing to supply valve.
- reduces lag time
Pilot Relay valve
reinforce multiple signal pressure on multiple trailer combinations
- uses supply air to overcome cracking pressure loss to signal relay valve.
-equalizes signal pressure
Convertor dolly
only trailer that doesn’t require spring brakes
Relay emergency (Non- charging)
-noting happens before 45PSI.
-no check valves.
-get signal from PPV
