Metal working – Method of mechanical manufacture – Converting
Reexamination Certificate
2002-06-11
2004-01-13
Vidovich, Gregory (Department: 3726)
Metal working
Method of mechanical manufacture
Converting
C029S402040, C029S402060, C029S402080
Reexamination Certificate
active
06675453
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method of remanufacturing a transmission assembly by providing a pocket in the end of an output shaft and a sun gear having a protruding center support hub which extends into the pocket, thereby supporting the output shaft to prevent tilting of the output shaft to reduce wear.
BACKGROUND OF THE INVENTION
Planetary gear set failure is one of the most common failure modes for vehicle transmissions. A prior art transmission is shown in
FIGS. 1 and 2
. As shown, the transmission
10
includes a Ravigneaux gear set
12
, which is a three-pinion design including a long pinion
14
and short pinion
16
(and a third pinion, not shown). The long pinion
14
is rotatable on a pinion pin
18
, which is supported by the carrier member
20
. The short pinion
16
is rotatably supported on the pinion pin
22
, which is also supported by the carrier member
20
.
An input sun gear
24
, shown in
FIG. 2
, is positioned in the pocket
26
shown in
FIG. 1
, and includes threads which are engaged with the threads of the pinions
14
,
16
.
The output shaft (drive shaft)
26
includes an integral flange
28
having apertures
30
,
32
which receive the pinion pin
22
and pinion
14
, respectively. Accordingly, the pinion pins
18
,
22
rotate about the centerline
34
with the output shaft
26
, including the flange
28
.
The output shaft
26
also includes an opening
36
which receives a pressed in pilot pin
38
.
As shown in
FIG. 2
, the output shaft
26
is supported on a case bushing
39
, and a reaction sun gear
40
is positioned around the output shaft
26
and driven by the long pinion
14
. The reaction sun gear
40
is supported within the reaction sun gear drum
42
.
Lubricating fluid
44
is distributed along the centerline of the sun gear
24
and output shaft
26
. The lubricating fluid
44
follows a leakage path
46
to lubricate bearings in the assembly.
Accordingly, in this configuration, the three pinions (only two shown) of the Ravigneaux gear set
12
are primarily responsible for keeping the output shaft
26
piloted with the input sun gear
24
. However, this structure may result in uneven loading and substantial wear on the pinions because the output shaft and input sun gear may tilt. This tilting would also wear the bushings on the input sun gear and output shaft, which may cause damage to these components, as well as damage to the governor bore. Also, the pilot pin may wear and also wear away the interior of the input sun gear
24
.
Accordingly, it is desirable to provide a method of remanufacturing a heavy-duty transmission assembly as described above in an inexpensive and effective manner.
SUMMARY OF THE INVENTION
The present invention provides a method of remanufacturing a transmission assembly to stabilize the output shaft wherein a pocket is machined into the input end of the output shaft, and a modified sun gear is provided with a protruding center support hub which extends into the pocket such that the input sun gear is positively piloted to the output shaft by the protruding center support hub, thereby preventing tilting of the output shaft and reducing wear.
More specifically, the invention provides a method of remanufacturing a transmission assembly including an output shaft having an input end positioned adjacent an input sun gear. The method includes machining a pocket into the input end of the output shaft and positioning a first roller needle bearing inside the pocket. The input sun gear is replaced with a modified sun gear having a protruding center support hub configured to extend into the pocket and cooperate with the first roller needle bearing, thereby supporting the output shaft to prevent tilting of the output shaft to reduce wear.
The method may also include the machining of a stepped portion off the O.D. surface of the output shaft near the input end, and positioning a second roller needle bearing between the machined O.D. surface of the output shaft and an I.D. surface of a reaction sun gear. The method may also include enlarging the I.D. surface of the reaction sun gear prior to the step of positioning the second roller needle bearing between the machined O.D. surface and the I.D. surface of the reaction sun gear.
This method may be useful in remanufacturing any transmission in which an output shaft is not sufficiently piloted with respect to an input member, such as an input shaft or an input sun gear.
A significant benefit of the invention is that the reduced tolerances on the various assembly components, as a result of improved piloting of the input sun gear and output shaft, may result in increased fluid pressure on the inside of the sun gear member and output shaft, thereby enabling lubrication fluid to be sprayed toward components to be lubricated as a result of the pressurization of the lubrication system from the reduced tolerances.
REFERENCES:
patent: 3747196 (1973-07-01), Whittington
patent: 4617711 (1986-10-01), McMinn
patent: 4930590 (1990-06-01), Love et al.
General Motors Powertrain Division, Hydra-matic 4L30-E Technician's Guide, pp. 1-101, 1992.
Cozart Jermie E.
General Motors Corporation
Hodges Leslie C.
Vidovich Gregory
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