Ministry of Transportation / Ministère des Transports
| Drivers & Vehicles | Highways | Road Safety | Trucks & Buses | Travel | Publications |
Home
Home > Air Brake Handbook > Key points to remember
Text size Enlarge Text Shrink Text
Search Search  |  

LICENCING

Key points to remember
 
  • The air brake subsystem of a trailer includes air tanks and automatic spring brake application.
  • Trailer couplers or ‘gladhands’ are used to connect the air brake system of the towing vehicle to the air brake system of the trailer.
  • In most cases, trailer couplers can be identified by their colour and are designed to prevent cross-connection.
  • When trailer couplers are cross-connected, the trailer service and spring brakes will not function correctly.
  • The trailer hand valve is used to apply the trailer service brakes independent of the towing vehicle’s brakes.
  • The trailer supply valve is usually a push/pull type valve near the driver that supplies air to the trailer’s brake system through the supply line.
  • The tractor protection valve prevents air loss from the towing vehicle.
  • When air pressure in the trailer supply line drops below 414 kPa (60 psi), the trailer spring brakes will apply automatically.
  • In an emergency when the trailer service brakes fail, the trailer spring brakes can be applied by using the trailer supply valve.
  • A trailer with a ‘spring brake priority system will allow the trailer spring brakes to release before the trailer service brakes have enough pressure to operate.