RES ACCEL Meaning: Cruise Control Parameters for On-Highway Truck (Caterpillar Engines)
Cruise Control
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| Figure 1.1 - Cruise Control and Set/Resume Switch |
Cruise Control Parameters
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| Figure 1.2 - Cruise Control Parameters |
The "Low Cruise Control Speed Set Limit" sets the lowest vehicle speed that will allow the cruise control to be set. Programming this parameter to the maximum value disables cruise control.
- Minimum: 24 km/h (15 mph)
- Maximum: 204 km/h (127 mph)
- Default: 204 km/h (127 mph)
2). High Cruise Control Speed Set Limit
The "High Cruise Control Speed Set Limit" sets the highest vehicle speed that will allow the cruise control to be set. If a driver attempts to set a vehicle speed higher than this limit, the "High Cruise Control Speed Set Limit" will be the cruise set speed. If the "High Cruise Control Speed Set Limit" is programmed to a value that is greater than the vehicle speed limit, the cruise control switches can be used to exceed the programmed vehicle speed limit.
- Minimum: 48 km/h (30 mph)
- Maximum: 204 km/h (127 mph)
- Default: 204 km/h (127 mph)
3). Engine Retarder Mode
The "Engine Retarder Mode" determines the operation of the auxiliary retarder output and the exhaust retarder output while the cruise control On/Off switch is in the ON position but the engine is not in cruise control. This does not determine engine retarder operation while the engine is in cruise control. Also, this does not allow engine retarder operation while the engine is in cruise control.
The following modes are allowable options:
- Coast
- Latch
- Manual
When the "Engine Retarder Mode" is programmed to the coast mode, the engine retarder is enabled only while the service brakes are being applied. When the Engine Control Module (ECM) is programmed to the latch mode, the engine retarder stays enabled after the service brakes are released. A direct, immediate pressure on the brake pedal latches the engine retarder in the ON position and the engine retarder will remain in the ON position until the accelerator pedal is depressed.
When the ECM is programmed to the manual mode, the cruise control switch is not required to be in the ON position. When the ECM is programmed to the manual mode, the engine retarder will activate when all of the following conditions are met:
-The engine retarder switch is in the ON position.
-The engine rpm is greater than 800 rpm.
-The engine is not being fueled.
- Alternative: Coast, Latch
- Default: Manual
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| Figure 1.3 - Coast (Engine Retarder Operation) |
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| Figure 1.4 - Latch (Engine Retarder Operation) |
4). Engine Retarder Minimum VSL Type
The "Engine Retarder Minimum VSL Type" defines the use of the "Engine Retarder Minimum Vehicle Speed" parameter. The "Engine Retarder Minimum VSL Type" provides the following two options:
- Hard Limit
- Soft Limit
If the "Engine Retarder Minimum VSL Type" is programmed to the Hard Limit, the engine retarder will turn off when the value that is programmed into the engine retarder minimum vehicle speed is reached.
If the "Engine Retarder Minimum VSL Type" is programmed to the Soft Limit, the engine retarder will remain on and the retarder will have a value that is below the value that is programmed in the engine retarder minimum vehicle speed. The engine retarder will remain on until the parameters that would normally turn off the engine retarder are met.
In both cases, the engine retarder will remain off until vehicle speed is higher than the programmed value of the engine retarder minimum vehicle speed and the engine retarder has been engaged again.
The following diagram (Figure 1.5) illustrates the engine retarder operation for both options of the "Engine Retarder Minimum VSL Type". The engine retarder parameter is programmed to the manual option and the parameter for the engine retarder minimum vehicle speed is programmed to 48 km/h (30 mph).
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| Figure 1.5 - Hard Limit/Soft Limit (Engine Retarder Operation) |
Note: When the vehicle speed drops below the engine retarder minimum vehicle speed and the parameter is programmed to the hard limit, the engine retarder turns off. When the vehicle speed drops below the engine retarder minimum vehicle speed and the parameter is programmed to the soft limit, the engine retarder remains on.
If the engine retarder minimum vehicle speed has been programmed to 0 km/h (0 mph), the programming of the parameter for the "Engine Retarder Minimum VSL Type" does not affect the operation of the engine retarder.
5). Engine Retarder Minimum Vehicle Speed
The "Engine Retarder Minimum Vehicle Speed" determines the minimum vehicle speed limit for the engine retarders to turn ON. Below this vehicle speed, the ECM will not turn on the engine retarder unless the vehicle is stationary. If the vehicle is stationary, the vehicle speed is 0 km/h (0 mph). If the vehicle speed signal was not being read by the ECM, the vehicle could be moving but the vehicle speed signal would be 0 km/h (0 mph). If engine retarder minimum vehicle speed is programmed to 0 km/h (0 mph) the engine retarder will operate at all vehicle speeds. This parameter affects both the engine retarder and any auxiliary retarder such as a BrakeSaver.
- Minimum: 0 km/h (0 mph)
- Maximum: 204 km/h (127 mph)
- Default: 0 km/h (0 mph)
6). Auto Retarder in Cruise
The "Auto Retarder in Cruise" determines the vehicle speed in kilometers per hour (km/h) or miles per hour (mph) above the cruise set speed when the engine retarder will be activated. The engine retarder switch must be in the ON position and the cruise control must be set for this feature to operate. Programming the "Auto Retarder in Cruise" parameter to zero disables this feature. This parameter affects the engine while the cruise control is activated.
Note: This parameter only affects the factory installed engine retarder (compression brake). This parameter does not affect an auxiliary braking device or Brakesaver.
The actual level of braking is limited by the settings of the retarder switch. For example, the retarder will not come on if the retarder is switched off.
If soft cruise control is programmed to yes, the retarder will not come on until the vehicle speed is 5 km/h (3 mph) above the cruise set speed. The Caterpillar Electronic Technician (ET) will change an attempt to program 2 km/h (1 mph) or 3 km/h (2 mph) for this parameter to 5 km/h (3 mph) if "Soft Cruise Control" is programmed to "Yes".
- Minimum: 0 km/h (0 mph)
- Maximum: 16 km/h (10 mph)
- Default: 0 km/h (0 mph)
7). Auto Retarder in Cruise Increment
The "Auto Retarder in Cruise Increment" requires the "Auto Retarder in Cruise" parameter to be programmed above zero. "Auto Retarder in Cruise Increment" determines the increment in kilometers per hour (km/h) or miles per hour (mph) when the medium level of engine retarder will activate. "Auto Retarder in Cruise Increment" also determines the increment in kilometers per hour (km/h) or miles per hour (mph) when the High level of engine retarder will activate. Programming the parameter to zero will allow the retarder to come on in the high mode when the programmed "Auto Retarder in Cruise" speed is reached. The "Auto Retarder in Cruise" speed must be set above the cruise set speed. This parameter affects the engine while the cruise control is activated. The actual level of braking is limited by the settings of the retarder switch. For example, the retarder will not come on if the retarder is switched off.
- Minimum: 0 km/h (0 mph)
- Maximum: 8 km/h (5 mph)
- Default: 3 km/h (2 mph)
8). Cruise/Idle/PTO Switch Configuration
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| Figure 1.6 - Cruise/Idle/PTO Switch Configuration |
"Cruise/Idle/PTO Switch Configuration" defines the function of the Set/Resume switch for "Accel" mode and "Decel" mode. This parameter affects cruise control mode, idle mode and PTO mode.
- Alternative: "Set/Decel-Res/Accel"
- Default: "Set/Accel-Res/Decel"
9). Soft Cruise Control
"Soft Cruise Control" provides a 8 km/h (5 mph) operating range around the cruise control set speed in order to provide a smoother cruise control. "Soft Cruise Control" controls the cruise speed within the following range:
- 4 km/h (2.5 mph) below the set vehicle speed at full load
- 4 km/h (2.5 mph) above the set vehicle speed at no load
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| Figure 1.7 - Soft Cruise Control |
- Alternative: No
- Default: Yes
"Adaptive Cruise Control" reduces the need to manually cancel cruise control when you approach a slower vehicle. The system responds by decreasing the cruise control set speed until a following distance is obtained. If the slower vehicle speeds up, the cruise control set speed will be adjusted in order to maintain the following distance. "Adaptive Cruise Control" will restore the original set speed when there are no vehicles within the range of control. Adaptive cruise control will not increase the cruise control set speed above the original setting. If the vehicle is approaching the target too rapidly, the ECM will turn off the cruise control.
- Alternative: Enabled
- Default: Disabled
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