Detent And Detent Regulator Valves; Reverse; Accumulator; Park-Neutral - Jeep 1979 CJ-5 Technical & Service Manual

AUTOMATIC TRANSMISSON 2C-5
reduced pressure intermediate clutch application for
smooth 1-2 shifts.
Drive-1 Range—Overrun Braking
Overrun engine braking in Drive-1 range first gear is
obtained by charging the rear servo, which applies the
rear band preventing the reaction carrier from rotating
in a clockwise direction (as viewed from the front of the
vehicle).
The 1-2 accumulator oil is directed to the accumulator
piston, which attempts to prevent the servo from apply-
ing. However, 1-range oil directed to the larger servo
piston will apply the band. Because 1-2 accumulator oil
is present, band apply force is decreased providing
smoother application.
Drive-2 Range—Second Gear
In second gear, the rear band is released. Intermediate
clutch oil is directed to the release side of the servo
piston along with 1-2 accumulator oil. This balances
first gear oil acting on the apply side of the servo piston,
and allows servo spring tension to move the servo piston
to the released position.
Reverse
In reverse, the rear band is applied to hold the reac-
tion carrier. Reverse oil is directed to the servo piston to
apply the band. To ensure that the band holds the reac-
tion carrier, line pressure is increased and no other oil
pressure is present in the servo to resist servo piston
movement.
1-2 Accumulator
In first gear, 1-2 accumulator oil charges the rear
servo accumulator preparatory to application of the in-
termediate clutch on 1-2 upshifts. Line oil pressure is
directed to the 1-2 accumulator valve and is further
regulated to become 1-2 accumulator oil. Modulator
pressure is directed to the 1-2 accumulator valve, caus-
ing 1-2 accumulator pressure to become sensitive to en-
gine torque. This provides smoother shifts in response to
engine torque output.
Detent oil is directed to the 1-2 accumulator valve to
raise 1-2 accumulator pressure during detent 1-2 shifts
to improve clutch life. In Drive-1 range, oil is directed to
the 1-2 accumulator valve to raise 1-2 accumulator pres-
sure to the same value line pressure. This increased
pressure, directed to the rear servo accumulator piston,
resists servo apply pressure and slows down the apply of
the rear band for a smoother manual shift to Drive-1
range first gear, or for a 2-1 downshift in Drive-1 range.
Detent and Detent Regulator Valves
When the accelerator pedal is fully depressed, the
detent valve train replaces the modulator as a controller
of shift points. Line pressure is fed through a small
orifice to one end of the detent valve. In normal throttle
operation, the cavity at this end of the valve is sealed by
a needle valve in the detent solenoid assembly. This line
pressure holds the detent valve train in an inoperative or
neutral position.
When the throttle is opened wide, the detent switch on
the accelerator pedal is closed, energizing the detent
solenoid. The needle valve is opened by the solenoid,
causing a pressure drop on the end of the detent valve.
The detent regulator valve spring then shifts the detent
valve causing the detent regulator to regulate detent oil
at a fixed pressure of approximately 60 psi (414 kPa).
When the detent valve shifts, it routes this fixed pres-
sure into the modulator passages. The detent valve train
also routes detent pressure into the detent passages to
the shift valve train. The detent upshift points are con-
trolled by detent pressure in the modulator passages,
and the detent downshifts by detent pressure in the
detent passages.
Detent pressure is directed to the 1-2 accumulator
valve to increase 1-2 accumulator pressure for clutch
durability during detent shifting. Detent pressure is
prevented from dropping below approximately 60 psi
(414 kPa) which, in turn, prevents line pressure from
dropping below approximately 105 psi (724 kPa).
In Drive-1 range, oil is directed to the detent regulator
valve and spacer; the spring then moves the detent and
regulator valves to the opposite end of the valve bore. Oil
pressure is also directed to the detent regulator valve
passage which is used as an exhaust when the valve is
regulating. Low range oil in these two areas prevents
the detent valve from regulating, and drive range oil
then passes through the detent regulator valve into the
detent and modulator passages at Drive-1 range pres-
sure of 150 psi (1 034 kPa). This increase in detent and
modulator pressures downshifts the 1-2 valve at speeds
below approximately 40 mph (64 km/h), and prevents
the transmission from upshifting regardless of vehicle
speed except in those vehicles which have a high numer-
ical axle ratio or are able to develop high engine rpm.
Park-Neutral
In Park and Neutral, pump supplied oil is routed to
and from the release side of the front servo through the
manual valve; then through the detent regulator valve,
modulator valve orifice, and back to the sump. Clutch
and band application does not occur in either of these
gearshift lever positions.
TOWING
Emergency Towing
If the vehicle is to be towed with the front or rear
wheels off the ground, towing speed must be limited to
30 mph (48 km/h) and the vehicle towed for a distance
no greater than 15 miles (24 km).