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Retarding performance charts provide an indication of the energy absorption capability of a given scraper power train on a specified continuous decline. Retarding performance charts serve to indicate the correct transmission gear selection and ground speed that should be used on a given grade. The charts help you avoid situations which may result in machine overspeed and damage to the machine. Retarding performance charts do not give an indication of the ability of the scraper to stop. Retarding performance charts do not give an indication of the ability of the scraper to remain stationary on the grades. |
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| Illustration 1 | g02592738 |
The film for retarding guidelines is located inside the cab.
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Maximum Operating Weight - The maximum operating weight of a loaded Scraper |
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Transmission Gear for the Downgrade - The selected gear for downhill travel |
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Downhill Slope Percentage - The percentage value of the slope for downhill travel |
The retarding capabilities for each gear will vary depending on the following conditions: rolling resistance, load, tire size and altitude.
Retarding Information and Conditions
The retarders equipped are an engine compression brake which releases compressed air before it can act as a spring and continue to propel the machine. Engage the retarder control in order to slow the machine ground speed. The tractor transmission must be in the DRIVE position and the throttle controls must be disengaged, in order for the retarders to engage. Refer to Operation and Maintenance Manual, "Operator Controls" for more information.
Use the retarder to help to stop the machine. The retarder will not completely stop the machine and the retarder will not hold the machine stationary. For maximum retarder performance on a given grade, selection of the proper gear is essential for effective operation of the retarder system. When starting down a known grade, refer the film for retarding guidelines in order to select the proper maximum gear limit. Select the proper maximum gear limit on the transmission control before you start down the grade. For more information on refer to Operation and Maintenance Manual, "Transmission Control". When the film does not address the current conditions, use the following rule: the desired gear on a downgrade is the gear that is required to go up the grade when the machine is loaded.
If the machine builds up excessive speed during retarding, the engine can overspeed and the transmission may upshift to protect the engine. If additional braking is still needed, depress the service brake. Maintain a constant vehicle speed. Do not speed up and brake. Do not stop in a short distance. Do not try to do all of the braking at the bottom of the hill. Excessive service brake use will damage the brake system.