Motorniveladora

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11/07

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Text Reference

ENGINE IDLE MANAGEMENT
- Cool Engine Mode
- Low Voltage Mode

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Engine Idle Management
Cool Engine Mode - In cold weather operation, the engine rpm will be set to 1000 rpm in
order to generate additional engine heat, keeping the engine warmer. This mode monitors the
coolant temperature and the intake manifold temperature. When the coolanttemperature is
below 80° C (176° F) or the intake manifold temperature is below 15° C (60° F) and the cool
engine mode is enabled, the machine will time out for 10 minutes. After ten minutes, if the
coolant temperature is below 70° C (158° F) and the machine has been in the cool engine mode,
the engine will be in the cool engine mode. If the machine has not been in cool engine mode
but theintake manifold temperature is less than 5° C (41° F), the engine will go into the cool
engine mode.
Low Voltage Mode - In this mode, the engine will ramp up to 1000 rpm when the battery
voltage drops below 24.5 volts for more than five minutes. When the battery voltage is greater
than 24.5 volts, the engine idle will return to low idle.
NOTE: The Engine Idle Management Strategies can not bereconfigured with Cat ET.

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11/07

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Text Reference

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Engine Brake
The C18 ACERT™ is equipped with an engine compression brake (arrow). The machine uses
valve timing change to open the exhaust valves before TDC during the compression stroke to
produce negative engine torque. The value to the machine from using the compression brake is
reduced engine overspeeds,reduced brake oil temperatures, and extended brake component life.
When the operator moves the engine brake selector switch in the cab to the AUTOMATIC
position a signal is sent to the Transmission/Chassis ECM. The Transmission/Chassis ECM
communicates with the Engine ECM over the CAT Data Link.
The Engine ECM activates the engine brake when the following conditions are met:
- Transmission/ChassisECM communicates to the Engine ECM the required retarding
level.
- The engine speed is above 1000 rpm
- The desired engine speed is at low idle.
The engine brake will be deactivated when the engine speed is below 950 rpm and reactivated
if the engine speed rises above 1000 rpm.

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Text Reference

The following cylinders are enabled when the selector switch isin the activated position.
Low (3 and 4)
Medium (1 and 2) (5 and 6)
High (1 and 2) (3 and 4) (5 and 6)
The ECM will disable injection to that cylinder while the engine brake is active.

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Text Reference

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This illustration shows the basic principle of engine compression brake retarding.
During normal engine operation without the engine brake enabled, thefollowing actions occur:
1. Intake stroke: The intake valve opens and air is forced into the cylinder by boost
pressure from the turbocharger.
2. Compression stroke: Air is compressed by the engine piston. The energy required to
compress this air is produced by the vehicle's driving wheels.
3. Power stroke: When the piston passes over top dead center and begins the power
stroke, the energy isreturned to the piston (and to the driving wheels). Essentially no
energy is absorbed and no net retarding work is done.
4. Exhaust stroke: Air is forced out through the exhaust.

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11/07

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Text Reference

When the engine compression brake is activated, the following actions occur:
1. Intake stroke: The intake valve opens and air is forced into the cylinder by boostpressure from the turbocharger.
2. Compression stroke: Air is compressed to approximately 3450 kPa (500 psi) by the
engine piston. The energy required to compress this air is produced by the vehicle's
driving wheels. Near top dead center, the compression brake opens the exhaust valve,
venting the high pressure air and dissipating the stored energy through the exhaust
system.
3. Power stroke:...