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orbit around the sun gear by internal teeth in the large case
or "pot" which is bolted to the ring gear.
Planet journals are integral with the planet support and
differential case. The orbit speed of the planets is conveyed to
the rear wheels through the differential case, differential pin-
ions, differential side gears and axle shafts.
Control of the sleeved sun gear is accomplished through
lateral movement of a coaxial "shifter sleeve" splined over the
sun sleeve. Left hand movement of the shifter collar and
sleeve produces sun gear stoppage when dove tail teeth in an
anchor ring attached to the housing engage similar teeth on the
approaching -face of the shifter
sleeve.
Right hand movement of the shifter collar and sleeve by
the vacuum control mechanism results in release from the
anchor ring. Clutching teeth on the opposite face of the shifter
sleeve then mesh with dove tail teeth projecting from the
planet case and ring gear assembly. Thus engaged, the sun
gear must turn at the speed of the ring gear, the planets are
locked in place, and only the reduction afforded by the pri-
mary drive gears determines mean rear wheel speed.
A positive, quick acting, two way vacuum system actuates
the shift collar and sleeve. The hand control is located on the
gear shift lever permitting simultaneous transmission and axle
shifts so that full advantage may be taken of all forward
ratios. The separable ring gear and simplified oil pick up and
distribution are other favorable features.
Description (Heavy-Duty 2-Speed Rear Axle). A heavy-duty
planetary 2-speed axle is available on 2% ton heavy-duty
trucks. This axle has spiral bevel type drive gear and pinion.
The drive pinion is straddle mounted between two opposed
taper roller bea"i-ings at outer end and a straight rolller bear-
ing at inner end.
A set of planetary gears and a sliding clutch gear,installed
between drive gear and differential, permits ratio change
from high to low or vice versa. Shift control is by electro-
mechanical means through a switch button on the gearshift
lever and a small reversible electric motor located on the
differential carrier.
Care. The rear axles used on Chevrolet trucks require very
little care or attention. The lubricant level should be checked
at each chassis lubrication and the differential carrier and in-
• 47 •
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