Features and Parameters

The ISL Gear Down Protection feature promotes increased fuel economy by encouraging the driver to operate as much as effectively possible in top gear, where fuel consumption is lower. This is accomplished by limiting vehicle speed in lower gears. Maximizing time in top gear means the engine runs in a lower rpm range, thus producing increased fuel economy and improved durability without compromising performance.

The imposed vehicle speed reduction is related to the load under which the engine is operating so that the operator always has access to full engine power when necessary. This is possible because Gear Down Protection senses engine load. It can be setup so that under heavy loads it would allow a maximum vehicle speed that would not adversely affect performance should the operator need to downshift. Under light loads, when downshifting would be unnecessary, Gear Down Protection can be setup to provide an appreciable limit in vehicle speed, thereby providing the operator with a strong incentive to remain in top gear.

Many factors affect the determination of the most appropriate settings to use when using this feature. These include engine and vehicle configuration values such as Tire Revolutions per mile, Governed Engine Speed, Rear Axle Ratio and Top Gear Transmission Ratio. Because of this, it is highly recommended that the Cummins Gear Down Protection Calculator be used when determining the most appropriate settings for your specific application.

Please also note that the appropriate speed settings are determined using vehicle and engine configuration values, not the Accelerator Maximum Vehicle Speed Limit.

Gear Down Protection
Choose this feature if the benefits of Gear Down Protection are desired. Applications which encounter a lot of highway driving profit most from this feature.

Gear Down Protection Heavy Load Vehicle Speed
Specify the maximum vehicle speed while the transmission is one gear down from top gear and operating under heavy load conditions.

Use the link below to access the Cummins Gear Down Protection Calculator to determine the most appropriate setting for your particular application.

The range is between 30 and 120 mph. It must be set less than or equal to the Road Speed Governor imposed Accelerator Maximum Vehicle Speed.

Gear Down Protection Light Load Vehicle Speed
Specify the maximum vehicle speed while the transmission is one gear down from top gear and operating under light load conditions.

Use the link below to access the Cummins Gear Down Protection Calculator to determine the most appropriate setting for your particular application.

The range is between 30 and 120 mph. It must be set less than or equal to the Road Speed Governor imposed Accelerator Maximum Vehicle Speed.

PowerSpec Gear Down Protection Auto-Calculate
The PowerSpec Gear Down Protection Auto-Calculate Option allows you to input the speed settings you desire for light and heavy vehicle loads or to have the optimum values automatically calculated by PowerSpec.

If you choose to have the values calculated, PowerSpec uses Engine Control Module (ECM) data at the time of transfer to calculate the optimum heavy and light load speed settings to encourage time in top gear while providing exceptional driveability. Since these values are calculated based on data currently in the ECM, the actual heavy and light load values are not available until the transfer is complete. The values will be displayed in the transfer report generated by PowerSpec after the transfer to the ECM is complete.

When you select the Don't Calculate option, you will be prompted to enter the values you desire for light and heavy load speed settings. It is suggested that the Don't Calculate option be selected by only experienced users.

Feature / Parameter

Range

Default

Gear Down Protection - Feature Option

Enable/Disable

Disable

Gear Down Protection Heavy Load Vehicle Speed - Parameter

30 - 120 mph

Calculated

Gear Down Protection Light Load Vehicle Speed - Parameter

30 - 120 mph

Calculated

PowerSpec Gear Down Protection Auto-Calculate - Feature Option

Enable/Disable

Enable