The “Jake” brake is an engine brake not to be confused with the exhaust
brake.
Engine brakes are devices that use the energy of engine compression to
provide vehicle retardation. Engine brakes provide the maximum retarding
power at rated speed; therefore, gear selection is important. The “World”
Allison transmission will automatically select the best downshift gear upon
actuation of the foot switch for the Jake Brake.
The engine brakes convert the engine to an energy absorbing device to
reduce the motorhome speed. This is accomplished by a hydraulic circuit
that opens the exhaust valves near the end of the compression stroke. The
amount of braking power available in a given engine series varies. Braking
power depends on turbocharger boost pressure, engine speed, compression
ratio, injector timing and when the brakes open the exhaust valves.
Engine brake controls with the fuel system consist of the following:
1.
A two-position selector switch.
2.
An ON/OFF switch, which is the foot switch.
3.
A throttle sensor.
Other switches for cruise control which affect engine brake operations
are:
1.
Cruise control ON/OFF and SET/RESUME switches (if the Engine
Brakes in Cruise Control feature is turned “OFF”).
2.
Service brake air pressure switch (if pedal activated engine braking is
enabled).
The two-position selector switch, located on the driver’s left console,
allows you to select the retarding power of one or two brakes.
“LOW” activates the engine brake on three cylinders.
“HI” activates the engine brake on six cylinders.
The engine ECM then electronically enables or disables the engine
brakes.
NOTE: Engine brakes cannot be enabled:
1.
When cruise control is active and if the engine brakes in cruise control
feature is turned OFF.
2.
When engine speed goes below 850 rpm.
3.
When an electronic fault code is active. The throttle sensor is part of
the accelerator pedal assembly located in the cab, and will deactivate
the engine brakes when depressed. The service brake pressure switch
is attached to the service brake air supply line. Applying the service
brakes while in cruise control will disengage the cruise and enable the
engine brakes. If the pedal activated engine brake feature is enabled,
the service brake pedal must be tapped before the engine brakes will
be activated. The Jake Brake can be used continuously down a hill, or
Chassis Information
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E X E C U T I V E
7 • 2 1 4
Engine braking
System (ISM Engine)
Summary of Contents for Executive 2001
Page 1: ......
Page 6: ...E X E C U T I V E SECTION 1 WARRANTY INFORMATION...
Page 7: ......
Page 22: ...E X E C U T I V E SECTION 2 OPERATING SAFETY...
Page 23: ......
Page 46: ...E X E C U T I V E SECTION 3 APPLIANCES EQUIPMENT...
Page 47: ......
Page 106: ...E X E C U T I V E CHAPTER 4 WATER LP GAS SYSTEMS...
Page 107: ......
Page 129: ...Water LP Gas Systems EXECUTIVE 4 1 2 9 NOTES...
Page 130: ...E X E C U T I V E SECTION 5 ELECTRICAL SYSTEMS...
Page 131: ......
Page 177: ...Electrical Systems 5 1 7 7 EXECUTIVE N NO OT TE ES S...
Page 178: ...E X E C U T I V E SECTION 6 UNIT CARE MAINTENANCE...
Page 179: ......
Page 203: ...Unit Care Maintenance EXECUTIVE 6 2 0 3 NOTES...
Page 204: ...E X E C U T I V E SECTION 7 CHASSIS INFORMATION...
Page 205: ......