GB1584165A - Differential mechanism - Google Patents

Description

(54) DIFFERENTIAL MECHANISM (71) We, DANA CORPORATION, a corporation organised under the laws of the State of Ohio, United States of America, of P.O. Box 1000, Toledo, Ohio 43697, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to differential mechanism of the type in which a casing enclosing differential pinions and gears is for example 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-casings 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 U.S. Patent Specification 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.

According to the present invention, there is provided a differential mechanism for a vehicle drive, comprising a hollow rotary casing consisting of two identical half-casings, each of said half-casings having a body which consists of a central portion that together with central portion of the other half-casing defines a space for a pair of differential pinions and a pair of differential gears, the said space being generated around the centre line of oppositely extending vehicle half-axles, the central portion of each half-casing having a semi-cylindrical exterior, a tubular half-trunnion extending coaxially with and at each end of said central portion, and a semi-annular ring gear mounting flange on the exterior of said half-casing adjacent the semi-cylindrical portion thereof, a differential pinion mounting pin extending across the centre line of the half-axles with its ends protruding into diametrically opposed radial apertures, one in each half-casing, a pair of differential pinions on the mounting pin, a pair of differential gears meshing with the pinions interiorly of said assembled casing Co- axially with said half-trunnions, a pair of trunnion bearings each circumjacent a respective trunnion formed by the half-trunnions of the half-casings, a ring gear closely circumjacent the cylindrical exterior of the assembled casing formed by said semi-cylindrical exteriors and drivingly connected to the mounting flange, the two half-casings being held in assembled relation.

ship by the trunnion bearings and said ring gear.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 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; Figure 2 is a vertical sectional view taken along the line 2-2 of Figure 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; Figure 3 is a horizontal sectional view taken along the line 3-3 of Figure 1 and showing one of the half-casings according to the invention in elevation with some associated parts being shown in section; and Figure 4 is a vertical sectional view of the half-casing taken along the line 4-4 of Figure 3 with the associated parts removed.

A differential mechanism embodying the invention comprises two half-casings 10 and 11.

The half-casings 10 and 11 are identical to each other and are assembled together by abutting flat diametric surfaces. Therefore, in further 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, in dicated generally by the bracket 13. The ex terior of the central portion 13 is semi-cylindri cal and is shown in section in Figure 4. The central portion 13 has an aperture 14 and it defines a open interior space 15 which has a spherical zone 16 concentric with the aperture 14. The apertures 14 extend radially, and are diametrically opposed, 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 Figures 2 and 3.

Each half-casing also has a pair of semicircular recesses 18 and 19 (see also Figure 4) which are concentric with the half-casings and a pair of oppositely extending tubular semiannular 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 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 apertures 14 aligned along the same 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 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.

The two differential pinions 26 have outer surfaces which are complementary to the circular 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 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 prior to the assembly of the snap ring 28, a large ring gear or "crown wheel" 35 is slid 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 the two half-casings 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 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 drivingly connected, for 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.

In summary, the differential mechanism for a vehicle drive shown in the drawings includes a hollow revolving casing consisting of two identical half-casings, each of the half-casings having a body consisting of a central portion that defined a space for differential pinions and gears that is generated around a center line of oppositely extending vehicle half-axles and that has a semi-cylindrical exterior, a tubular halftrunnion extending co-axially at each end 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 differential pinion mounting pin extending across the center line of the half-axles with its ends protruding into diametrically opposed 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 when the casing is assembled and a ring gear closely circumjacent the cylindrical exterior of the assembled casing and drivingly connected to the mounting flange. The two half-casings are held in assembled relationship by the trunnion bearings and the ring gear. A snap ring engages a groove circumjacent the halfcasings and engages the ends of the pinion mounting pin to prevent rotation thereof.

The snap ring can also be used to hold the halfcasings 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.

WHEAT WE CLAIM IS: 1. A differential mechanism for a vehicle drive, comprising a hollow rotary casing consisting of two identical half-casings, each of said half-casings having a body which consists of a central portion that together with central portion of the other half-casing defines a space

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. terior of the central portion 13 is semi-cylindri cal and is shown in section in Figure 4. The central portion 13 has an aperture 14 and it defines a open interior space 15 which has a spherical zone 16 concentric with the aperture 14. The apertures 14 extend radially, and are diametrically opposed, 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 Figures 2 and 3. Each half-casing also has a pair of semicircular recesses 18 and 19 (see also Figure 4) which are concentric with the half-casings and a pair of oppositely extending tubular semiannular 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 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 apertures 14 aligned along the same 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 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. The two differential pinions 26 have outer surfaces which are complementary to the circular 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 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 prior to the assembly of the snap ring 28, a large ring gear or "crown wheel" 35 is slid 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 the two half-casings 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 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 drivingly connected, for 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. In summary, the differential mechanism for a vehicle drive shown in the drawings includes a hollow revolving casing consisting of two identical half-casings, each of the half-casings having a body consisting of a central portion that defined a space for differential pinions and gears that is generated around a center line of oppositely extending vehicle half-axles and that has a semi-cylindrical exterior, a tubular halftrunnion extending co-axially at each end 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 differential pinion mounting pin extending across the center line of the half-axles with its ends protruding into diametrically opposed 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 when the casing is assembled and a ring gear closely circumjacent the cylindrical exterior of the assembled casing and drivingly connected to the mounting flange. The two half-casings are held in assembled relationship by the trunnion bearings and the ring gear. A snap ring engages a groove circumjacent the halfcasings and engages the ends of the pinion mounting pin to prevent rotation thereof. The snap ring can also be used to hold the halfcasings 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. WHEAT WE CLAIM IS:

1. A differential mechanism for a vehicle drive, comprising a hollow rotary casing consisting of two identical half-casings, each of said half-casings having a body which consists of a central portion that together with central portion of the other half-casing defines a space

for a pair of differential pinions and a pair of differential gears, the said space being generated around the centre line of oppositely extending vehicle half-axles, the central portion of each half-casing having a semi-cylindrical exterior, a tubular half-trunnion extending co-axially with and at each end of said central portion, and a semi-annular ring gear mounting flange on the exterior of said half-casing adjacent the semicylindrical portion thereof, a differential pinion mounting pin extending across the centre line of the half-axles with its ends protruding into diametrically opposed radial apertures, one in each half-casing, a pair of differential pinions on the mounting pin, a pair of differential gears meshing with the pinions interiorly of said assembled casing co-axially with said halftrunnions, a pair of trunnion bearings each circumjacent a respective trunnion formed by the half-trunnions of the half-casings, a ring gear closely circumjacent the cylindrical exterior of the assembled casing formed by said semi-cylindrical exteriors and drivingly connected to the mounting flange, the two halfcasings being held in assembled relationship by the trunnion bearings and said ring gear.

2. A differential mechanism according to claim 1, including means for preventing rotation of the pinion mounting pin, the pinions being rotatable on the pin.

3. A differential mechanism according to claim 2, wherein the rotation preventing means comprises a snap ring circumjacent the halfcasings and engaged with said ends of said pinion mounting pin.

4. A differential mechanism according to any of claims 1 to 3, wherein the interior surface of the central portion of each said body has a spherical configuration surrounding the radial aperture therein and the differential pinions have outer surfaces complementary thereto.

5. A differential mechanism according to any of the preceding claims, wherein the said space has a pair of radial end walls, providing bearings surfaces for the differential gears.

6. A differential mechanism for a vehicle drive substantially as hereinbefore described with reference to the accompanying drawings.