LOCKING DIFFERENTIAL

DIFFERENTIEL A MECANISME DE CALAGE

English Abstract

ABSTRACT OF THE DISCLOSURE
A locking system for a differential gear including a
differential carrier having a cavity within which a pair of bevel gears
and at least one pinion gear which meshes with the pair of bevel gears
are housed, the bevel gears being adapted to be splined to axial shafts,
the locking system including a locking means positioned within the
differential carrier between the differential carrier and at least one of
the bevel gears, the locking means including locking teeth or spline means,
at least one of the bevel gears being formed with co-operating teeth or
spline means, cylinder means formed in the differential carrier and housing
an actuator positioned to cause movement of the locking means relative to
the carrier whereby the locking teeth or spline means on the locking means
engages the teeth or spline means on the one bevel gear to prevent rotation
of the one bevel gear relative to the carrier to thereby lock the
differential gear.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A locking system for a differential gear including a
differential carrier having a body within which a pair of bevel
gears, and at least one pinion gear which meshes with said pair of
bevel gears, are supported, each of said bevel gears being adapted
to be splined to an axle shaft, said locking system including
locking means keyed or splined to said carrier between said carrier
body and at least one of said bevel gears so as to be capable of
axial movement relative to said carrier body, said locking means
including locking tooth or spline means located to one side of the
pinion gear and adapted to engage similar tooth or spline means
associated with said one bevel gear, said locking system further
including cylinder means defined by the body of the carrier and
located within the carrier on the other opposite side of the pinion
gear, and an actuator housed in the cylinder means and movably
supported therein to cause said axial movement of said locking
means relative to said carrier body whereby said locking tooth or
spline means on said locking means engages said tooth or spline
means on the one bevel gear to prevent rotation of the one bevel
gear relative to said carrier body to thereby lock said
differential gear.
2. The locking system of claim 1, wherein said locking means
includes an annulus splined to said carrier and slidable axially to
cause engagement between said locking tooth or spline means on said
annulus and said tooth or spline means associated with said one of
said bevel gears.
3. The locking system of claim 1, wherein said actuator comprises
a piston housed in a cylinder and connected to said locking means
to cause said axial movement of said locking means relative to said
carrier.
4. The locking system of claim 3, wherein said piston and cylinder
are annular and are arranged to surround an axle of the other of
said bevel gears, said piston being connected to said locking means

by means of an annular sleeve surrounding said bevel gears and
including aperture means through which the or each pinion gear is
located.
5. The locking system according to claim 3 or 4, wherein passage
means are provided for charging said cylinder with compressed air
under the control of valve means.
6. The locking system of claim 1, wherein said locking means is
supported in the carrier body for sliding movement therein between
an unlocking position wherein the bevel gears are supported in the
carrier for rotation relative to the carrier, and a locking
position wherein the locking means engages the carrier and said one
bevel gear to prevent rotation of said one bevel gear relative to
the carrier and thereby lock said one level gear to the carrier,
said actuator causing the locking means to slide between the
locking and unlocking positions, and said carrier including a
carrier tooth located inside the carrier, said one bevel gear
including a gear tooth located inside the carrier, and the locking
means including locking teeth so that when the locking means is in
the locking position, the locking teeth engage the carrier tooth
and the gear tooth to prevent rotation of said one bevel gear
relative to the carrier.
7. The locking system of claim 1 or 6, wherein said locking means
includes a sleeve supported for sliding movement in the carrier,
said locking tooth or spline means being connected to the sleeve
for sliding movement therewith, the cylinder means comprises an
inside annular chamber axially aligned with the sleeve, and the
actuator includes a piston supported for movement in the annular
chamber and connected to the sleeve to move the locking tooth or
spline means of the locking means into engagement with the locking
tooth or spline means on said one bevel gear.
8. The locking system of claim 1 or 6, wherein said locking means
includes a sleeve supported for sliding movement in the carrier,
said locking tooth or spline means being connected to the sleeve
for sliding movement therewith, the cylinder means comprises an
inside annnular chamber axially aligned with the sleeve, and the

sleeve includes a side opening, and the pinion gear extends through
said side opening.
9. A kit for converting a differential to a locking differential,
said kit including a differential carrier having a body within
which a pair of bevel gears and at least one pinion gear are
adapted to be supported, a locking means adapted to be keyed or
splined to said differential carrier so as to be capable of axial
movement relative to said carrier body between said carrier body
and at least one of said bevel gears, said locking means including
locking tooth or spline means adapted to be located to one side of
the pinion gear, and a replacement bevel gear formed with tooth or
spline means which are adapted to cooperate with said tooth or
spline means associated with said locking means, said carrier body
defining a cylinder located on the other opposite side of the
pinion gear and adapted to house an actuator for causing axial
movement of said locking means relative to said carrier when in
use, thereby preventing rotation of the one bevel gear relative to
said carrier.

Description

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This invention relates to locking differentials for
motor vehicles and other machines.
Various types of locking differential have been
proposed, such as for example, in Patent Publications AU-B-
511,665, AU-B-511,700, AU-A-41 ,416/78 and GB-A-2,019,511.
In each of the above examples, the locking mechanism is
either complex, difficult or inconvenient to actuate and/or
requires substantial modifica~ion to the rear axle housing
and/or differential carrier to accommodate the mechanism.
There is a need for a locking differential which is
simple to manufacture or to convert an existing differential
and which nevertheless does not require substantial
modification to the differential axle housing.
The invention therefore provides a locking system for a
differential gear including a differential carrier having a body
within which a pair of bevel gears, and at least one pinion gear
which meshes with said pair o~ bevel gears, are supported, each of
said bevel gears being adapted to be splined to an axle shaft, said
locking system including locking means keyed or splined to said
carrier between said carrier body and at least one of said bevel
gears so as to be capable of a~ial movement relative to said
carrier body, said locking m~ans including locking tooth or spline
means located to one side of the pinion geax and adapted to engage
similar tooth or spline means associated with said one bevel gear,
said locking system further including cylinder means defined by the
body of the carrier and located within the carrier on the other
opposite side of the pinion gear, and an actuator housed in the
cylinder means and movably supported therein to cause said axial
movement of said locking means relative to said carrier body
whereby said locking tooth or spline means on said locking means
engages said tooth or spline means on the one bevel gear to prevent
rotation of the one bevel gear relative to said carrier body to
thereby lock said differential gear.

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The invention also provides a kit for converting a
differential to a locking differential, said kit including a
differential carrier having a body within which a pair of bevel
gears and at least one pinion gear are adapted to be supported, a
locking means adapted to be keyed or splined to said differential
carrier so as to be capable of axial movement relative to said
carrier body between said carrier body and at least one of said
bevel gears, said locking means including locking tooth or spline
means adapted to be located to one side of the pinion gear, and a
replacement bevel gear formed with tooth or spline means which are
adapted to cooperate with said tooth or spline means associated
with said locking means, said carrier body defining a cylinder
located on the other opposite side of the pinion gear and adapted
to house an actuator for causing axial movement o~ said locking
means relative to said carrier when in use, thereby preventing
rotation of the one bevel gear relative to said carrier.
One particularly preferred form of the invention
will now be described with reference to the accompanying
drawing which is a somewhat schematic sectional elevation
of a differential carrier incorporating a locking system
embodying the present invention. It will be appreciated
that part only o~ the dif~erential gear adapted to be
locked by the locking system embodying the invention is
shown for purposes of clarity.
As is usual, the differential includes a
differential carrier 1 which rotatably supports a pair of
bevel gears 2, 3 in the usual manner as well as a pinion
gear 4 which meshes with the bevel gears 2, 3 and is
mounted for rotation on a shaft 5 supported by the casing
1. Half axles Al and A2 have their splined ends engaging
splined openings in the bevel gears 2, 3 and passing through
the casing 1 in the manner shown.
The locking system embodying the present invention
comprises an annulus 6 formed with outwardly directed spline
teeth 7 which engage mating s~ ne teeth 8 formed in the
differential casing 1 surrounding the bevel gear 3 so that
the annulus 6 is axially slidable in the splines 8 relative
to the carrier 1. The annulus 6 is similarly formed with

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4.
inwardly directed spline teeth 9 which are adapted to
co-operate with spline teeth 10 formed around the lower
periphery of the bevel gear 3.
~xial movement of the annulus 8 is achieved by
means of an annular piston 11 arranged in an annular
cylinder 12 formed in the casing 1 around the other bevel
gear 2, and to which is attached an actuating sleeve 13
which extends from the piston 11 to the annulus 6, to which
it is riyidly attached. The sleeve 13 is formed with
a cut-out portion 19 around the pinion 4 which enables axial
movement of the sleeve 13 by means of the piston 11 to
cause engagement between the spline teeth 9 on the
annulus 6 and the corresponding spline teeth 10 on the
bevel gear 3.
The piston 11 is actuated by means of compressed
air, or some other suitable fluid under pressure, which
is communicated to the cylinder 12 by means o a passage
14 formed in the casing 1, and around the inlet opening
to which an annular collar 15 is sealingly arranged.
Compressed air is delivered by means of a pipe 16 which is
connected to a fitting (not shown) on the axle casing
(not shown).
A piston return spring 17 is housed in a pocket
in the casing 1 and bears against the piston 11 as shown
to bias the piston towards it de~activated position.
It will be appreciated that compressed air may
be delivered to the cylinder 12 via the ~ipe 16 and passage
14 by actuation of a valve suitably located in the driver's
cabin of the vehicle to which the differential is fitted.
The compressed air drives the piston 11 axially in the
cylinder 12 and causes the sleeve 13 to axially move the
annulus 6 to cause engagement between the spline teeth 9
and 10 to thereby lock the bevel gear 3 against rotation.
When differential action is again required, the valve in
the driver's cabin is returned to the de-activated position
84/9/3

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and the sp~ing 17 returns the piston 11 to the position
shown in the drawing whereby the spline teeth 9 on the
annulus 6 are disengaged from the spline teeth 10 on
the bevel gear 3.
While the above described embodiment of the
invention is presently preferred, it should be appreciated
that the specific form described is not essential to
the invention. For example, the annulus 6 may be replaced
by a segment formed with spline teeth similar to 9 adapted
to engage the spline teeth 10 on the bevel gear 3, in
which case the sleeve 13 would be replaced by a suitable
connecting rod or element. Similarly, the piston 11
may be replaced by some form of mechanically or electrically
operated actuator. For example, the annulus or segment
lS may form part of an electro-magnetic actuator to cause
suitable locking of the bevel gear.
In the above described embodiment, the differential
casing 1 is adapted to be substituted for an existing
diferential casing in a non-locking differential to thereby
convertt}le di~ferential into a locking differential. Of
course, the diPEerential casing may be substituted at the
time of initial manufacture where a locking differential
is required. Although substitution of the described
differential casing is presently preferred, it may be
possible where the structure of the differential casing
is such as to facilitate conversion, to convert an existing
non~locking differential casing to a locking differential
casing by the addition of the locking system components
described above.

Representative Drawing