Mazda Automatic Transaxle JA5A-EL. Manual — part 17

AUTOMATIC TRANSAXLE

K–49

K

R Position

Outline

• When R position is selected, the hydraulic circuit of the manual valve is switched which engages the reverse

clutch and low and reverse clutch.

• Gear changes can not occur in R position. However, when the driving speed is over 30 km/h {19 mph} during

forward movement and R position is selected, the low and reverse brake does not operate and the driving force

is not transmitted due to the operation of the reverse inhibit valve. With this mechanism, driving safety is

ensured by preventing misoperation of the selector lever.

AMU0517A557

K–50

AUTOMATIC TRANSAXLE

Operation

• The driving force of the input shaft is transmitted to the front sun gear via the reverse clutch hub because the

reverse clutch is engaged.

• When the front sun gear rotates counterclockwise, it causes the front pinion to revolve counterclockwise.

However, since the front planetary carrier is fixed to the low and reverse brake via the low clutch drum,

revolution of the front pinion is locked. As a result, the front pinion can not revolve around the front sun gear but

rather starts to rotate clockwise on its center, causing the front internal gear to also rotate clockwise. The

driving force is transmitted to the output gear in clockwise rotation because the front internal gear is integrated

with rear planetary carrier. (This is the opposite to rotation during forward movement.)

• As the driving force transmitted from the output gear to the idler gear tries to rotate the reduction internal gear

counterclockwise and to revolve the reduction pinion counterclockwise, the force also tries to rotate the

reduction pinion counterclockwise and to rotate the reduction sun gear clockwise as the load from the vehicle is

applied to the reduction planetary carrier. This load acts as a force that prevents the reduction planetary carrier

from rotating counterclockwise.

• However, the reduction pinion overcomes the load from the vehicle to revolve counterclockwise while rotating

counterclockwise as the reduction sun gear is fixed by the reduction brake.

• This counterclockwise revolution of the reduction pinion is transmitted to the reduction planetary carrier and

then to the reduction gear.

• During deceleration, the torque is transmitted from the driving wheels in the opposite direction of that during

acceleration, and engine braking is applied. The torque from the opposite direction is also transmitted in R

position because the one-way clutch is not used.

AUTOMATIC TRANSAXLE

K–51

K

AMU0517A558

K–52

AUTOMATIC TRANSAXLE

R Position (Reverse Inhibition Control)

Outline

• The driving force of the input shaft is transmitted to the reverse and high clutch drum, and then to the front sun

gear through the reverse clutch, causing the front sun gear to rotate counterclockwise.

• None of the low and reverse brake are operating, however, so this force is not transmitted to the output gear.

AMU0517A559