Second Gear

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Fig 1: Identifying Second Gear Planetary Operation

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SECOND GEAR ROTATION SPEED REFERENCE

Planetary gear	Front	Rear
Internal gear	N_R (output)	N_R
Planetary carrier	N_C	N_C (output)
Sun gear	0 (fix)	N_S (input)

NOTE:

The front internal gear and the rear planetary carrier are integrated.
The front planetary carrier and the rear internal gear rotate at the same speed.

Suppose the gear ratio in second gear is i₂ ,

Fig 2: Identifying 2nd Gear Ratio Formula (1 Of 4)
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From formula (1), the relation between the gear ratio in second gear and the rotation speeds of the front and the rear planetary gear sets is indicated in formulas (2) and (3).
(Z_RF +Z_SF ) N_C =Z_RF N_R +Z_SF N_S

(2)

(Z_RR +Z_SR ) N_R =Z_RR N_C +Z_SR N_S

(3)
From the result N_S =0 in formula (2).

Fig 3: Identifying 2nd Gear Ratio Formula (2 Of 4)
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Here we substitute formula (4) in formula (3).

Fig 4: Identifying 2nd Gear Ratio Formula (3 Of 4)
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Therefore,

Fig 5: Identifying 2nd Gear Ratio Formula (4 Of 4)
Courtesy of MAZDA MOTORS CORP.
As a result, the gear ratio in second gear is 1.545.