General Description of the Payload Cycle
A new payload cycle starts when the truck finishes dumping the previous payload and the body is fully down.
- After the previous payload has been dumped the truck travels back to the loading area. The truck is considered to be "travelling empty" during this time. The truck may need to wait if the "loading area" is blocked by other trucks that are being loaded. The truck is considered to be "stopped empty" in this case. When the loader is ready, the truck is positioned under the loader. The truck is still considered to be "travelling empty" during this positioning.
- The truck is considered to be in the "Loading state" after the truck has come to a complete stop under the loader and the first load hits the body. The truck remains in the "Loading state" until the truck has shifted into second gear.
- The loader will begin loading material onto the truck. As the loader passes are applied, the truck continues to be in the "loading state".
- When all of the loader passes have been applied, the truck pulls away from the loading area. When the truck reaches the speed of
5 km/h (2 mph) or travels0.16 km (0.1 miles) the truck is considered to be in the "travelling loaded state". - As the truck reaches the "dumping area" the truck may need to wait because the "dumping area" may be blocked by other trucks that are dumping loads. The truck is considered to be "stopped loaded" during this time. The "dumping area" will eventually be clear. The truck will then be positioned for dumping. The truck is again considered to be "travelling loaded" during this positioning. The truck is considered to be in the "dumping state" when the body is raised in order to start dumping. The truck stays in the "dumping state" until the truck body is completely lowered. During this phase of the "dumping cycle", the VIMS considers the truck to be "stopped loaded".
- Once the body is lowered the present payload cycle ends and a new cycle begins.
Calculating the weight of the payload begins as material is being loaded onto the truck. The truck must be ready to load for the weighing process to begin. The following conditions must be met in order to provide optimum accuracy:
- The minimum weight of the loader pass must be greater than 10 tons.
- The truck must not be moving.
- The transmission should be in neutral.
- Setting the parking brake is recommended.
The message center will be in the background mode and the external payload status lamps are off. The external payload display (if equipped) will display the current payload weight.
When the loader dumps the first pass onto the truck body, the suspension cylinder pressure increases sharply. The sharp increase in pressure starts the "loading state". The following information is shown on the message center which replaces the background mode:
- A payload weight of zero
- The status of "LOADING"
The external payload status lamps signal the loader operator with a green light to continue loading.
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| Illustration 1 | g00490540 |
The pressure within the suspension cylinders is not stable for a few seconds after the loader pass. The suspension cylinders are still recoiling from the sudden application of a large mass. After the pressure in the suspension cylinders has stabilized, the first pass weight is calculated. The pass weight is then displayed on the message center. The message is shown below. The external payload status lamps continue to signal the loader operator with a green light.
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| Illustration 2 | g00490541 |
Note: NNN.N represent the present payload weight.
With each additional loader pass, more material is loaded onto the truck. This causes the suspension cylinder pressures to increase sharply. Each sharp increase in suspension cylinder pressure adds another loader pass. The pressure within the suspension cylinders must stabilize before the calculation of the payload weight is completed. The new payload weight is displayed on the message center. This message is shown below.
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| Illustration 3 | g00490541 |
Note: NNN.N represent the present payload weight.
If the last pass indicator is enabled the VIMS Truck Payload System calculates a running total of the weight for all passes. The red payload status lampsbegin to flash in order to warn the loader operator when the system has determined that one additional pass will result in a payload of at least 95 percent of the target payload. This is the present payload weight plus the weight of the most recent pass. The following message is shown on the message center:
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| Illustration 4 | g00490542 |
Note: NNN.N represents the present payload weight.
After the final loader pass (the last pass) has been completed, the red payload status lamps are turned ON solid in order to inform the loader operator that the present payload weight is greater than 95% of the target payload weight. The following message is shown on the message center:
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| Illustration 5 | g00490544 |
Note: NNN.N represents a value that is greater than 95% of the target payload weight that was programmed into VIMS with the service program code PAYCONF.
When the truck begins to travel away from the loading site after being loaded the following message is shown on the message center:
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| Illustration 6 | g00490546 |
Note: NNN.N represents the last calculated payload weight.
The payload measurement system measures the weight of the load again once the truck has exited the load site. The measurement is made when the truck has shifted into second gear. The payload information automatically disappears from the message center after the load has been measured. The message center then returns to the background mode. This indicates that the "loading state" is complete. The truck is now "travelling loaded".
Automatic Calibration Adjustment
Whenever the truck is "stopped empty" the VIMS truck Payload System will automatically adjust the calibration. The calibration is adjusted for weight variations such as fuel load and carryback weight that may affect accuracy. The Carryback weight includes any material that is stuck to the body and under the body. The amount of adjustment that can take place is limited to a relatively small range around the original calibration value that was established with the service program code PAYCAL.
Collapsed Suspension Cylinder Detection
Whenever the truck is "travelling empty" at a speed less than
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| Illustration 7 | g00490547 |
Press the "F1" key for more information. For example, the second line of the message center will display additional diagnostic information:
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| Illustration 8 | g00490548 |
Automatic Payload Communication
When the VIMS RS-232 Broadcast port is connected to a telemetry system, the VIMS Truck Payload System will send the payload weight via wireless communications to an off-board site. The payload weight is sent at the following key points in the payload cycle:
- Immediately after the VIMS has successfully weighed each loader pass. This is true only if the last pass indicator is on.
- Immediately after the VIMS has estimated the weight of each loader pass.
- The truck travels in the loaded state for a distance that is greater than
.16 km (0.1 miles) or the truck has shifted to "2nd" gear. - Immediately after the truck has finished the loading cycle.
The payload information is stored in the VIMS electronic control module during operation of the truck. The payload information that is stored in the on board memory can be analyzed after the information is downloaded. The process of moving data from the onboard memory to the off-board service tool is called downloading.
A service tool (laptop computer) that is running the VIMSpc99 off-board software is used in order to download the payload information. The service tool is connected to the onboard system via a RS-232 service port. The downloaded payload information can be analyzed with the VIMSpc99 off-board software.
Note: Refer to the VIMSpc99 User Manual, FEBJ0047 for additional information on the VIMSpc99 off-board software.
While the service tool is connected to the onboard system, VIMSpc99 can display payload information in real-time. Payload information such as payload weight, suspension cylinder pressures, payload status and more can be displayed at the same time. The payload information is updated once per second.
Additionally, VIMSpc99 can be used to initiate a calibration (the service program code PAYCAL) of the VIMS Truck Payload System while the service tool is connected.