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Engine/Gear Parameters
Gear Fast/Run Slow
Gear Fast/Run Super Slow
Description:
Gear Fast/Run Slow ( GFRS) and Gear Fast/Run Super
Slow ( GFRSS) are specing methods to promote improved
fuel economy through lower engine speed and faster
gearing. GFRS/GFRSS only applies for a multi-torque
rating allowing at least a 1750 lb-ft upper torque value.
GFRS/GFRSS is applicable for van, reefer, and tanker
applications, with a GVW of 80,000 lbs. The following
table matches axle ratios with the appropriate drive axle
tires revolutions per mile, specifi cally for the GFRSS
designation.
While GFRS/GFRSS is not an electronically-
programmable parameter, it has been included in this
handbook to supplement the Eaton Top 2 transmission
programming parameters. The results of employing
GFRS/GFRSS can be seen by entering appropriate data
into Cat Design Pro.
Available:
C-15, C-16, C13, C15 heavy duty engines
(Provided suffi cient torque is available - see
recommendation below)
Range:
Axle Ratio
Drive Axle Tires
Revolutions/Mile
1300 - 1350 RPM @ 65 MPH
3.21 513 to 531
3.25 506 to 525
3.36 490 to 508
3.42 481 to 499
3.55 464 to 480
3.58 460 to 476
Recommendations:
✔ Caterpillar recommends that the engine have at
least 1750 lb-ft of torque available for GFRSS