General System Description

CONSTRUCTION
The Chrysler 47RH is a 4-speed automatic transmission. Fourth gear is an overdrive range.

The 47RH is a dual unit design. The assembly consists of an automatic transmission with an overdrive unit attached at the rear. First through third gear ranges are provided by the clutches, bands, overrunning clutch and planetary gear set in the transmission. Fourth gear range is provided by the overdrive unit. Overdrive ratio is 0.69:1.

The overdrive unit contains an overdrive clutch, direct dutch, planetary gear set and overrunning clutch. The overdrive clutch is applied in fourth gear only. The direct clutch is applied in all ranges except fourth gear.

The governor and park lock assemblies are located inside the overdrive unit. The unit must be removed and disassembled for service access to the park lock and governor components.

OPERATION
First, second, third, and reverse gears are controlled hydraulically, like any other conventional transmission. Fourth gear is controlled by a manually operated switch in the instrument panel. The switch is in circuit with the overdrive solenoid (on the valve body) and the powertrain control module.

In the ON position, current flows through the switch to the solenoid for the 3-4 shift sequence. The transmission must be in third gear before a 3-4 upshift will occur.

The overdrive solenoid will not be energized and a 3-4 upshift will not occur when the control switch is in the OFF position.