Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
This invention relates to the field of differential mechanisms and, more
particularly, to differential mechanisms of the type in which the casing enclosing
the differential pinions and gears is rotated by the drive shaft of a powered vehicle.
It previously has been suggested that the casing for such a differential
mechanism might be fabricated from opposed half-casings of identical shape and
configuration. However, the half-caslngs are held in their assembled position
by means of bolts which extend through bored holes in flanges of the half-casings
and may require nuts on their ends~ Such a structure appears in Musgrave Patent
No. 3,365,984 issued January 30, 1968.
All rotating differential casings must include suitable bearings for the differential
casings and also interiorly of the casings for the differential gears and differential
pinions. If the differential casing is to rotate, it must also have means for securing
to the casing the ring gear or "crown wheel" to which power is applied by the
vehicle drive shaft.
It is therefore the principal object of the instant invention to provide a
differential mechanism which comprises a casing consisting of two half-casings,
the half-casings being so designed as to enable their assembly into a hollow
structure by the use of the bearings in which the casing is mounted for rotation and
the ring gear of crown wheel, these parts being necessary for operation
and serving a second function of holding the half-casings in assembled
relationship .
It is yet another object of the instant invention to provide a differential
mechanism comprising a casing consisting of two half-casings which are
so designed as to enable the half-casings to mount the differential gears and
pinions, to accept the vehicle half-axle ends and to be held in assembled relationship
merely by the addition thereto of bearings for the casing trunnions and
a ring gear or crown wheel.
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BRIEF DESCRIPTION OF THE DR~WINGS
Fig. 1 is a view in end elevation of a differential mechanism embodying
the invention with some parts being broken away, the view not showing the
casing mounting bearings or axle housing;
Fig. 2 is a vertical sectional view taken along the line 2-2 of Fig. 1 and
showing the differential gears and pinions, the pinion mounting pin, the trunnion
bearings and the ring gear and drive shaft as well as the inner ends of the
vehicle half-axles, some parts being shown in section and some parts being broken
away;
Fig. 3 is a horizontal sectional view taken along the line 3-3 of Fig. 1 and
showing one of the half-casings according to the invention in elevation with some
associated parts being shown in section; and
Fig. 4 is a vertical sectional view of the half-casing taken along the line
4-4 of Fig. 3 with the associated parts removed. -
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DESCRIPTION OF PREFERRED EMBODIMENT
A differential mechanism embodying the invention comprises two half-casings
10 ancl 11. The half-casings 10 and 11 are identical to each other and are
assemlbled together by abutting flat diametric surfaces. Therefore, in further
5 description of the half-casings 10 and 11, the component parts of the half-casings
will be described interchangeably.
Each half-casing 10 or 11 has a main body 12 which includes a central
portion 13, indicated generally by the bracket 13. The exterior of the central
portion 13 is semi-cylindrical and is shown in section in Fig. 4. The central portion
13 has a polar aperature 14 and it defines a open interior space 15 which has a
circular polar zone 16 concentric with the aperture 14. The polar apertures 14
extend radially relative to the axial center line of the half-casing and to the
center lines of a pair of half-axles 17 shown in part in Figs. 2 and 3.
Each half-casing also has a pair of semi-circular recesses 18 and 19
(see also Fig. 4) which are concentric with the half-casings and a pair of
oppositely extending tubular semi-annnular trunnion halves 20 and 21. A larger
semi-annular flange 22 is located at one side of the central portion 13 and has an
inner face 23 lying in a radial plane. A circumferentially extending groove 24
intersects the polar aperture 14 and extends around the cylindrical
surface of the central portion 13 of the body 12. Each of the two half-casings 10
and 11 has a flat diametric surface 25 which surfaces abutt each other when the
half-casings are assembled to form a closed casing that is open axially from end to
end with the polar apertures 14 aligned along a single diameter.
The operative elements of a differential mechanism according to the invention
include two differential pinions 26 which are rotatable about a mounting pin 27
extending across the casing and protruding into the two polar apertures 14. The pin
27 is of such length that it extends sufficiently far toward the exterior of the half-
casings 10 and 11 so that a snap ring 28 can be spread around the two half-casings
and inserted into the groove 24 engaging in a cross slot 29 cut into each end of the
mounting pin 27. The mounting pin 27 is shown as having a helical lubrication
groove 30 formed in its surface.
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The two differential pinions 26 have outer surfaces which are complementary
to the polar zones 16 and a pair of spherical bushings 31 are positioned between the
surfaces of the polar zones 16 and the outer surfaces of the differential pinions
26. Similarly, a pair of annular bushings 32 are positioned between the outer
5 sides of a pair of differential gears 33 and a pair of radial surfaces 34 on the
interior of the half-casings 10 and 11.
After the insertion of the bushings 31 and 32, the differential pinions 26,
the differential gears 33 and the pinion mounting pin 27, but prlor to the
assembly of the snap ring 28, a large ring gear or "crown wheel" 35 is slid
10 over the bodies of the half-casings 10 and 11 up to and against the radial inner
faces 23 of the flanges 22.
After the ring gear 35 has been positioned circumjacently the two
half-casings 10 and 11 and against the flanges 22 it is secured in position by a
plurality of machine screws 36. The snap ring 28 is then inserted in place and
15 the two half-caslngs 10 and 11 are "unitized" for purposes of handling and
eventual assembly into the vehicle upon which the differential mechanism is to
be used.
The half-trunnions 20 and 21 now form complete supporting trunnions for
the differential casing comprising the two half-casings 10 and 11. The outer surfaces
20 of the now complete trunnions can then be turned to the correct diameter to
receive a pair of trunnion bearings 37 which, in turn, are mounted in and supported
by a pair of axle housings fragmentarily indicated by the reference numbers 38.
The inner ends of the opposed half-axles 17 are inserted into the open centers
of the differential gears 33 to which they may be driveingly connected, for
25 example, cooperating with a plurality of serrations 39 or similar means. The
vehicle also will have a main drive shaft 40 and a drive pinion 41 which
is engaged with the ring gear 35 upon complete assembly of the vehicle.
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In summary, the present invention concerns a differential mechanism for
a veh~cle drive including a hollow revolving casing consisting of two identical half-
casings, each of the half-casings having a body consisting of a central portion that
defines a space for differential pinions and gears that is generated around a center
5 line of oppositely extending vehicle half-axles and that has a semi-cylindrical
exterior, a tubular half-trunnion extending co-axially at each end of the central
portion, a radial aperture at the pole of the central portion and a semi-annular
ring gear mounting flange on the exterior of the half casing adjacent the semi-
cylindrical portion thereof. The differential mechanism also includes a
10 differential pinion mounting pin extending across the center line of the half-axles
with its ends protruding into the polar apertures when the casing is assembled,
a pair of differential pinions on the mounting pin, a pair of differential gears
positioned interiorly of the assembled casing co-axially with the half-trunnions
and meshed with the pinions, trunnion bearings circumjacent the half-trunnions
15 when the casing is assembled and a ring gear closely circumjacent the
cylinderical exterior of the assmbled casing and drivingly connected to the mounting
flange. The two half-casings are held in assembled relationship by the trunnion
b0arings and the ring gear. A snap ring engages a groove circumjacent the
half-casings and engages the ends of the pinion mounting pin to prevent rotation
20 thereof. The snap ring can also be used to hold the half-casings together during
handling and shipment after the differential pinions and gears have been
installed but before the trunnion bearings and ring gear have been mounted.
In accordance with the provislons of the patent statutes, the principle and
mode of operation of the invention have been explained and illustrated in its
25 preferred embodiment. However, it must be understood that the invention
may be practiced otherwise than as specifically illustrated and described
without departing from its spirit or scope.
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