2001/06/11 Caterpillar

Off-Highway Truck:

785C (S/N: 5AZ1-263 and 264-UP; APX1-UP; 1HW1-UP)

789C (S/N: 2BW1-302 and 303-UP)

793C (S/N: ATY1-UP; 4AR1-UP; 4GZ1-UP)

797 (S/N: 5YW1-UP)

784B (S/N: 5RK1-UP)

784C (S/N: 2PZ1-UP)

785B (S/N: 6HK1-UP)

789B (S/N: 7EK1-UP)

793B (S/N: 1HL1-UP)

Reference: Service Manual, SENR6059, "Vital Information Management System VIMS"

Caterpillar's 10/10/20 rule states "that no more than 10 percent of the payloads may exceed 1.1 times the target payload of the truck and no single payload shall exceed 1.2 times the target payload of the truck". The Maximum Payload Speed Manager provides the customer with a way to comply with the 10/10/20 rule. This method limits the performance of the machine. The performance of the machine is limited when the weight of the payload is greater than 1.2 times the target payload. When the weight of the payload is 1.2 times the target payload, the brakes and steering are at the maximum certifiable levels. Limiting the performance of a machine that is overloaded protects the machine and the operator. The operator of the loading tool is also forced to load the machine correctly.

Operation of the Maximum Payload Speed Manager

The Maximum Payload Speed Manager compares the actual payload weight on the machine to an overload setting. When the VIMS has determined that the machine is overloaded, the machine is slowed down by limiting the shift range of the transmission and the engine speed is reduced at the limited gear. The payload weight is monitored as the machine shifts to second gear.

Machine Response to the Weight of the Payload

The Maximum Payload Speed Manager will activate the overload events when the weight of the payload exceeds the set limit regardless of the location of the truck. The speed limiting of the machine is activated when the weight of the payload exceeds the set limit regardless of the location of the truck. This behavior will remain active until the payload is dumped and the weight of the payload is cleared. The limiting of the machine's speed and the VIMS messages cease automatically after the payload has been dumped and the machine is returned to normal operation.

The weight of the payload is calculated as the truck is shifted into second gear (second gear weighing). The new weight of the payload that is determined during the second gear weighing is then used to determine if limiting the speed of the machine is necessary.

Once the Maximum Payload Speed Manager has determined that the truck is overloaded, the following actions are initiated:

• The shift range of the transmission is limited to second gear.

• High idle of the engine is limited to 1750 rpm.

• The point for automatic retarding is reduced to 1750 rpm.

The settings that are listed above are not adjustable.

Example of the Operation of the Maximum Payload Speed Manager

The Project Manager for a site has determined that the gross machine weight (GMW) for the site's 793C equipped with MSD bodies is 240 tons and the loads should never exceed a limit of 288 tons. In order to achieve these objectives the Project Manager would set the parameters of the Maximum Payload Speed Manager to the values that are listed below:

Target Payload Setting - 240 tons

Payload Overload Limit Setting - 120% (288/240=120%)

With these settings the Maximum Payload Speed Manager will function in the manner that is listed below:

• The payload weight is set to 240 tons.

• The overload warnings will occur above 264 tons.

• The engine speed will be limited to 1750 rpm in second gear above 288 tons.

• The external payload display will show the current payload weight.

Illustration 1	g00796765
Maximum Payload Speed Manager setup for a 793C Off-Highway Truck

Compatibility of the Maximum Payload Speed Manager of the VIMS 9.62X Class of Onboard Software with Earlier Machine Software and Hardware Configurations

The features of the Maximum Payload Speed Manager that are available with the 9.62X VIMS class of onboard software will depend on the level of software that is flashed into the other electronic control modules that are installed on the truck. The version of electronic control module that is installed on the truck will also affect the features of the Maximum Payload Speed Manager that are available. The following tables list the features of the Maximum Payload Speed Manager that are available with earlier versions of trucks.