03 Brake System
Brake System
• Front brakes are 17” air applied disc
• Rear brakes (Figure 3-1) double as parking brake
- Park brakes are spring applied – air released
- Two large 16.5 x 7” drum brakes
- Park brake remains applied even if air pressure is lost
• If air pressure is lost - A buzzer and warning lamp will alert you
• Chassis is equipped with automatic slack adjusters (Figure 3-2) - No brake adjustment required
The rear brakes on the PowerGlide chassis are also used as the parking brakes. This provides you the holding power of two large drum brakes to prevent your coach from rolling, even when fully loaded on a 20% grade.
A decrease in air pressure while driving will not cause an immediate loss of brakes. If a significant leak develops in the air system, at approximately 60 PSI you will be alerted by a lamp on the instrument panel, and by an audible alarm. As you apply the brakes, the air supply holding the park brakes in the released position will gradually be depleted. When system pressure drops to approximately 40 PSI the rear brakes will set. This allows you sufficient time to pull over to the side of the road.
NOTE: The rear brakes have dual chambers – one for the service brakes and one for the park brake. The service brakes are air applied and spring released. The park brake is spring applied and air released.
The brake system is equipped with automatic slack adjusters that avoid the need to manually adjust your brakes. Each time you step on the brake pedal, if adjustment is needed, the adjusters will take up the slack.
Compressed Air System
40’ Non -Tag Tank Drains
44' Tag Tank Drains
The compressed air system is comprised of multi-air storage tanks. The primary tank stores and supplies air for the rear brakes, the secondary tank stores and supplies air for the front brakes.
When air is compressed it becomes hot. As it cools, condensed moisture forms in the system. The air system is equipped with an air dryer to remove most of this moisture. The dryer has an automatic moisture ejector that releases the trapped moisture back into the atmosphere. However, some moisture will form in the system beyond the dryer, and make its way into the storage tanks. As moisture collects in the primary and secondary tanks, it displaces the area needed for air storage, thus requiring that the tanks be drained periodically.
The air system is equipped with air tank drains conveniently located in the compartment with the DEF tank. Each drain is attached to a different tank. These drains should be opened regularly for a few seconds to remove any moisture trapped in the tanks.
Air Dryer
The Tiffin PowerGlide chassis air brake system features a Haldex Purest air dryer (Figure 3-3), which removes the condensed moisture from compressed air. The air dryer is equipped with a desiccant cartridge that needs to be changed every 36 months. The dryer is located on the driver's side (LH) frame rail (behind the rear axle).
Engine Compression Brake
The engine compression brake (Figure 3-4):
• Improves braking power
• Reduces the chance of overheating brakes on steep grades
• Works in conjunction with the transmission to help slow the vehicle
• Has two stages (low and high) for varying terrain
All brakes will build up heat when being used due to friction – this is normal. However, excessive use of the brakes when descending a grade can result in excessive heat and can cause “brake fade” or a loss of braking power, even with disc brakes. The proper way to use your brakes is to go slowly enough that a fairly light, occasional use of the brakes will keep your speed from increasing.
NOTE: DO NOT maintain continual brake pedal pressure when descending a hill with any type of brake system.
Rather, down-shift the transmission to slow the vehicle and make light, intermittent brake applications to control downhill speeds. By utilizing the transmission gears and compression brake, continual use of the brakes will not be necessary. When using the transmission’s lower gears to slow the vehicle on hills, be careful not to exceed the governed speed of your engine. If engine-governed speed is exceeded, the transmission will shift up to the next range, rapidly increasing the speed of your vehicle. If you find that you are continually using the brakes to maintain a safe speed and to keep the RPM within this range, slow the vehicle down even further and shift the transmission to a lower gear.
