Saab 95 1967, Service Manual

Page: 377 / 610

ted to the engine by means of a clutch housing of light
alloy, which also encases the differential. All gear wheels,
except the reverse gear wheel, are helical cut and in con-
stant mesh with one another.
Shaft borne gears are either carried on needle bearings or
directly splined.
The transmission has synchronizers on both the primary
shaft and the countershaft.
Gear changing movements are transmitted from the steer-
ing column gear shift lever to three shift forks. These shift
forks are able to slide on their shafts and are locked in
their respective gear positions by spring loaded poppet
balls, which fit into recesses made for this purpose on the
shafts.
In addition, arrangements are provided which make it im-
possible to engage two gears simultaneously.
The working of the transmission is shown by the expla-
natory sketch.
In lst gear, power is transmitted from the primary shaft
to the counter shaft via an intermediate gear behind the
freewheel. The 1st speed gear, which is carried on the
countershaft, is looked to the shaft by a sliding sleeve.
The power is then transmitted to the 3rd speed gear,
which is borne on the primary shaft, and thence to the
3rd gear on the pinion shaft.
In 2nd gear, power is transmitted to the pinion shaft
in the same way as when driving in 1st gear, except
that the engagement sleeve now locks the 2nd speed
gear, instead of the lst to the countershaft.
The power is then transmitted to the 4th speed gear on
the main shaft and thence to the 4th gear on the pinion
shaft.
In 3rd and 4th gears, power is transmitted from the pri-
mary shaft to the 3rd or 4th speed gear, as applicable,
which is then locked to the primary shaft by means of
a sliding sleeve. In reverse, power is transmitted from
the primary shaft to the countershaft by way of the
previously mentioned intermediate gear behind the free-
wheel. The reverse gear, splined to and sliding on the
countershaft, meshes directly with the 3rd gear on the
pinion shaft, thus turning the latter, together with the
gears, in the reverse direction.
Syn chronizer unit
The synchronizer unit functions as described in the fol-
lowing:
When the synchronizer sleeve is made to mesh with, for
instance, the dog ring on the 3rd speed gear, it pushes
in front of it an internally tapered bronze ring. This
ring has external teeth corresponding to those of the
gear dog ring. The bronze ring is able to change its posi-
tion in relation to the sleeve by half a tooth space, and
it also rotates at the same speed as the primary shaft.
If the speed of the 3rd speed gear differs from that of
the primary shaft at the moment when engagement
should commence, the teeth on the bronze ring will
move into the way of the internal teeth on the sleeve,
thus preventing the sleeve from moving in the direction
of the 3rd speed gear. The internal taper of the bronze
ring is then forced over the external 3rd gear taper and
the friction will cause the gear and sleeve to rotate at
the same speed. The path is thus opened for the sleeve,
enabling the synchronizer sleeve teeth to engage the
teeth of the dog ring on the 3rd speed gear.
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DIAGRAMMATIC AR RANGEMENTbF FREEWHEEL
1. Clutch shaft - .
2. Freewheel hub «593"
3. Freewheel sleeye’"
4. Roller "’
S. Coil spring