The Dodge 47RH and 47RE heavy-duty automatic transmissions
The 47RH four-speed Torqueflite® transmission was used on Ram 2500 and 3500 pickups with the 8.0-liter V-10 or 5.9-liter Cummins Turbo-Diesel engines. It had a torque capacity of 450 lb-ft and trailer towing capacity of up to 19,000 pounds GCWR, the highest ratings for a one-ton truck at the time. The 47RH included a lockup torque converter, hydraulically operated three-speed planetary transmission, and an electronically-controlled overdrive unit which could be locked out with a button.
The 47RH transmission was essentially created by upgrading the 46RH transmission and the overdrive unit:
- The input shaft enlarged 0.070 inches at the torque converter clutch oil feed hole
- The torque converter clutch oil feed hole was shot-peened inside
- Pressure angle on spline between the intermediate shaft and the front planetary gear unit changed from 37.5°to 30°
- A fifth pinion was added to the front planetary gear carrier
- The reverse band widened and changed from a single to double wrapped setup
- The reverse servo unit was revised
- The case was redesigned for these changes.
Overdrive unit revisions included the following:
- A ninth disc was added to the overdrive direct drive clutch
- Output shaft governor shaft cross hole shot peened to increase fatigue life
- The output shaft selective annealing process was revised
- The governor drive key was changed from a semi-circular "Woodruff" to a 1/ 4-inch square to reduce stress on the shaft
The torque converter clutch was not previously available with the diesel engine. The V-10 and diesel versions of the transmission had different shift schedules to match their torque curves.
The 47RH was eventually replaced by the 47RE. (The 4 was the number of gears, including an overdrive; the capacity rating of 7; R for rear wheel drive; and H for hydraulic control, or E for electronic control). The primary difference appears to have been the name, since Chrysler press materials noted that even the 47RE had hydraulic shift control (other than the overdrive, which was electronically activated in both automatics).
The 47RH and 47RE were reserved for V10 and Cummins diesel engines.