9
EA(B)O-6X06
01/2018 Rev. 1
1. General Information
Gear Ratio
Definition and Calculation
Gear ratio of a transmission speed is the relationship between the transmission’s output and input speeds, with
the said gear shifted. If the gear ratio is greater than 1, it means that the transmission’s output speed is slower
than the input speed and it is said that there is a reduction in the speed. On the other hand, if the gear ratio is
less than 1, the transmission’s output speed will be faster than the input speed and, in this case, it is said that
there is an overdrive.
The gear ratio is calculated by dividing the number of teeth of the driven gear by the number of teeth of the driving
gear of that specific speed and multiplying by the ratio of the input gear set.
Example:
Input gear ratio = C ÷ I (input gear set) = 44 ÷ 29 = 1.52
1st speed ratio = M ÷ C (1st speed) x 1,52 (input gear set) = 49 ÷ 12 x 1,52 = 6.19
This means that the 1st speed gear ratio is 6.19:1 or, in other words, with the transmission shifted into the 1st
speed, the engine (input shaft) makes 6.19 revolutions for every revolution of the transmission’s output shaft.
So, in 1st gear, there is a reduction in the output speed.
EA(B)O-6106/6206A
EA(B)O-6106/6206B
Torque
N.m
600
600
Lb.ft
442
442
Z
Ratio
Z
Ratio
Input Shaft (I)
Countershaft (C)
29
44
1.52
29
44
1,52
1st
Countershaft (C)
Mainshaft (M)
12
49
6,19
12
49
6,19
2nd
Countershaft (C)
Mainshaft (M)
17
38
3,39
17
38
3,39
3rd
Countershaft (C)
Mainshaft (M)
27
37
2,08
27
37
2,08
4th
Countershaft (C)
Mainshaft (M)
33
29
1,33
33
29
1,33
5th
Countershaft (C)
Mainshaft (M)
Direct
1,00
Direct
1,00
6th
Countershaft (C)
Mainshaft (M)
47
24
0,77
52
25
0,73
Reverse
Countershaft (C)
Reverse Idle Gear (R)
Mainshaft (M)
12
29
45
5,69
12
29
45
5,69
Z
=
Number of teeth
C
= Countershaft
M
= Mainshaft
R
= Reverse Idle Gear
I
=
Input Shaft
Gear Ratio
