Operating instructions H A K 0 OH-Model no. 239
PLANETARY GEARS (simple)
A. General:
On fully automatic transmissions, the ratios are engaged with the aid of
planetary gears.
gears have the following advantages:
-Planetary
very compact construction.
- distribution of torque on several gears.
- can be shifted under load.
This model shows a simple planetary gear, also known as a planetary
train.
gear
The planetary gear train has the following basic elements:
- 1 internally-geared wheel (green)
- 3 planetary gears (red)
- 1 sun gear (yellow)
1 planetary carrier (transparent)
-
The ratios and the different directions of
rotation of a planetary gear train result
from securely holding the sun gear,
internally-geared wheel or planetary carrier.
If two elements are connected positively at
the same time, the planetary gear is locked
(it can no longer rotate within itself), in
other words, the direct gear is engaged
(ratio 1: 1).
The following abbreviations are used in the table:
Pt for planetary carrier, So for sun gear, Ho for Internally-gearedwheel.
Engagement alternatives:
Drive
:
Output
:
Held securely
:
1
So
Pt
Ho
2
So
Ho
Pt
3
Pt
So
Ho
4
Pt
Ho
So
5
Ho
So
Pt
6
7
Ho Ho/Pt
Pt So
So --
Diagram
bt,
Reve,.e gear 12}
Shifting altem.tiw8
of a 8mple pl8natary gear
,\L__~~~~~~gee'
-239-
It can be seen from the illustration and the table that there are a total of 7
engagement alternatives. However only 2-3 alternatives are used in a
motor vehicle. In practice, planetary gear trains are used more and more.
B. Use of model:
Now all ratios found in the above table can be demonstrated on the model.
Only the number of teeth on the internally-gearedwheel and sun gear are
of significance for the transmission ratio. The planetary gears are
intermediate gears and do not change the ratio.
Internally-geared wheel: 72 teeth, sun gear: 30 teeth
Table for gear shifting and for calculating the ratios in all divisions
z,
Shifting
:~\.
of
\'.
)1
.,
,y
~z./~~
.
IInternally-geared
Output
wheel
wheel
I Planetarycarrier
Internally-geared wheel
i . z,.
l.!,~
Z2
Ratio
I.
7230
2,It: of
Reverse gear
Note:
The components
inserted through
+
Zz
."
'-1+~
ZI
JO
/. 1 +2,'1z
1st geer
~ t: 1
Planetarycarrier
Sun gear
i .1 toz,
i;.
.
+41,2=
Sun gear
Planetary carrier
-=~---
Plenetery carrier
Planetary carrier
-
IHeld securely:
Gear
Internally-geared wheel
Sun gear
Sun gear
Drive
i
~
C:l)
Igeafs
30
+?F
-1;"2:/
2nd gear
,.
1:1
3rd geer
are securely held with the aid of the brass pin, which is
the transverse rail into the appropriate bores.