Progressive Shift
Progressive Shift encourages drivers to upshift from a lower to a higher gear prior to reaching the engine’s governed speed. The low
range threshold of operation is defined by a Gear Ratio (parameter 12307). The maximum engine speed will be limited to a maximum
progressive shifting engine speed (parameter 12306) when the transmission is a ratio less then the Gear Ratio. The engine will be allowed
to run up to maximum rated engine speed when the transmission is in a ratio greater or equal to the Gear Ratio.
The Gear Ratio is calculated as follows:
Gear Ratio = Transmission Output Shaft Speed (rpm)/Engine Speed (rpm)
The following will help you calculate and enter your gear ratio value via DDDL, Minidiag or Reprogramming Station.
SAMPLE TABLE:
Step 1:
Select the gear you wish to limit the rpm up through and the next gear up from this; example 9th and 10th gears. Identify the ratios for
each gear.
9th gear = 1.34 ** 10th gear = 1.00
Step 2:
Invert each gear ratio by dividing 1. In this example, the inverted ratio for 9th gear will be .75 and 10th gear will be 1.00.
Step 3
Select a number between the two inverted gear ratios. We’ll select .87 and this will be our gear ratio for progressive shift (parameter
12307). Enter this ratio into parameter identifier 12307. The follow is a screen shot of the VCU parameter field in DDDL.
SPECIAL NOTE: If you are entering this value using DDDL and using English units of measure, divide your result by 1.63: This is
your final Gear Ratio for Progressive Shift.
A formula to calculate Gear Ratio to Progressive Shift has been provided for you on DDC’s Extranet. Click on the
following link to access this formula. http://www.detroitdiesel.com/Support/OnHighway/Service_Information/Specialized_Service_Information/MBE_Progressive_Shift.asp