Low/Reverse Clutch Assembly. Description and Operation

Low/Reverse Clutch Exploded View

Low/Reverse Clutch, Sectional View

Low/Reverse Clutch Mechanical Operation

The low/reverse clutch is a braking clutch that holds the low one-way clutch (OWC), which is splined to the rear planetary carrier. The low/reverse clutch is applied in manual LOW, REVERSE and 1st gear below 8 km/h.

Hydraulic pressure from the regulator valve in the valve body pushes the low/reverse clutch piston against the low/reverse clutch pack to apply the clutch. The rear planetary carrier is held stationary to the transmission case when the clutch is applied.

Low/Reverse Clutch Hydraulic Circuits (Applied in REVERSE)

Line pressure is supplied to the low/reverse 456 regulator valve by the pump in every gear and in all manual lever positions. To apply the low/reverse clutch, the SSD solenoid pressure varies the low/reverse 456 regulator and check valves. As the low/reverse 456 regulator valve moves, it supplies the clutch control bypass valve and the low/reverse 456 check valve with regulated line pressure through the CBR1/C456 circuit. The low/reverse 456 check valve directs regulated line pressure to the opposite side of the 456 regulator valve through the CBR1/C456 FDBK circuit to gradually reduce the low/reverse 456 clutch apply. The low/reverse clutch is applied in PARK, REVERSE, NEUTRAL, 1st gear below 8 km/h and manual LOW position.

In REVERSE, the ON/OFF SSE and SSD solenoid pressures and the line pressure from the manual valve in the REVERSE circuit act on the clutch control bypass valve to set it for low/reverse clutch application. Regulated line pressure from the CBR1/C456 circuit is directed by the clutch control bypass valve through the CBR1 circuit to apply the low/reverse clutch.

Low/Reverse Clutch Hydraulic Circuits (Applied in PARK, NEUTRAL, LOW or 1st gear at speeds below 8 km/h 5 mph)

When the low/reverse clutch is applied in PARK, NEUTRAL, LOW or 1st gear below 8 km/h, only the ON/OFF SSE pressure acts on the clutch control bypass valve. Line pressure from the REVERSE circuit is not supplied by the manual valve.

Low/Reverse Clutch Hydraulic Circuits (Released)

When the low/reverse clutch is released in 1st gear above 8 km/h, in 2nd and 3rd gears the SSD solenoid pressure is removed from the low/reverse 456 regulator and check valves, which position the valves to block line pressure and exhaust the low/reverse clutch. The SSE solenoid pressure is removed from the clutch control bypass valve to set it for overdrive clutch application (4, 5, 6).

When the low/reverse clutch is released in 1st gear at speeds above 8 km/h, in 2nd and 3rd gears the exhaust backfill is supplied to the low/reverse 456 regulator valve and the clutch control bypass valve through the EXH BF circuit from the manual valve. The circuit is directed to the low/reverse 456 check valve, the low/reverse clutch and the overdrive clutch (4, 5, 6) to fill the unused circuits with non-pressurized transmission fluid.

When the low/reverse clutch is released in 4th, 5th and 6th gears, the reverse 456 regulator valve supplies regulated pressure to the clutch control bypass valve through the CBR1/C456 circuit. When the ON/OFF SSE is in the OFF position, regulated pressure is directed to the overdrive clutch (4, 5, 6).

For detailed information on valve body hydraulic circuits and solenoid operation, refer to
For additional information, refer to: Transmission Description - System Operation and Component Description (307-01A Automatic Transmission - 6-Speed Automatic Transmission - 6F35, Description and Operation).