Automatic locking clutch with sliding clutch ring

An improved clutch of the type having concentric and spaced apart driving and driven members with a clutch ring in engagement with one of the members and urgeable into a simultaneous engagement with the other member is provided. A fixed cam member is provided nonrotational with respect to the driving and driven members. A second cam member is slidably movable around the first cam member whenever the clutch ring is in simultaneous engagement with the driving and driven members. A cam follower is in a cammed engagement with the first cam member and is movable axially apart from the first cam member into cammed engagement with the second cam member. The cam follower further urges the clutch ring into a simultaneous engagement with the driving and driven member whenever the driving member rotates with respect to the driven member.

FIELD OF THE INVENTION 
The present invention relates, in general, to locking clutches, and more 
particularly to a fully automatic locking clutch having a sliding clutch 
ring. 
BACKGROUND ART 
It has long been recognized that locking clutches employing sliding clutch 
rings ideally should provide quick and positive engagement between the 
vehicle's driving member and the vehicle's driven member. A clutch 
providing quick and positive engagement between these members minimizes 
the problems resulting from a "snap start" condition. This condition 
typically occurs when the vehicle makes a transition from the two wheel 
drive mode to a four wheel drive mode with the sliding clutch ring being 
partially engaged to both the driving and driven members. As this occurs, 
in certain instances the vehicle's power source attempts to transmit more 
torque to the clutch ring than the clutch ring can withstand when in the 
partially engaged condition. As a result, the clutch fails to lock up with 
the result being that the clutch ring becomes damaged and rendered 
inoperable. 
Prior attempts to produce locking clutches with sliding clutch rings have 
utilized either a moving cam type arrangement or a fixed cam type 
arrangement to activate the sliding clutch ring and produce clutch lockup. 
In general, a moving cam type arrangement is inherently slow to lock the 
driving and driven members. The principal reason is that a moving cam 
cannot be resisted with sufficient torque to rapidly effect clutch lockup 
without generating excessive heat while running in the locked condition. 
The heat must be dissipated by the vehicle's axle, with the effect being 
that the heat can burn out the vehicle axle bearings. Consequently, a 
locking clutch with a sliding clutch ring activated simply by a moving cam 
type arrangement does not produce a quick and positive lockup and thus is 
susceptible to the "snap start" problem. Typical prior art moving cam type 
arrangements are shown by Kagata, U.S. Pat. No. 4,163,486, and Goble, U.S. 
Pat. No. 3,656,598. 
Locking clutches employing solely a movable cam type arrangement are 
susceptible to yet another problem. In the two-wheel drive mode, 
especially in cold weather situations where lubricants between the driving 
and driven members are cold, the driving member tends to rotate with 
respect to the driven member. In some instances, the rotational movement 
of the driving member may be as much as one-half the rotational movement 
of the driven member. Locking clutches employing the moving cam type 
arrangement in such a situation tend to effect clutch lockup. This becomes 
a major problem especially when the vehicle is moving at significant 
speeds. 
Fixed cam type arrangements overcome these problems by typically producing 
faster lockup than moving cam type arrangements while resisting the 
tendency to inadvertently lock up when the vehicle is operated in the two 
wheel drive mode. Once the driving and driven members are in the locked 
condition, one came surface moves with respect to the other resulting in a 
chatter or a "ticking" between the cam surfaces. This typically results in 
a very high wear with the driving and driven members jumping in and out of 
a locked condition. Locking clutches utilizing solely fixed cam type 
arrangements are shown by Petrak, U.S. Pat. No. 3,217,847. 
The present invention solves these problems of the prior art by providing a 
locking clutch utilizing a sliding clutch ring activated by both a fixed 
and moving cam. The sliding clutch ring initially is urged into an engaged 
condition between a driving and driven member by a fixed cam. 
Subsequently, once the locking clutch has effected engagement, a moving 
cam increases the engagement and maintains the locked condition. In this 
manner, the present invention provides a locking clutch having the quick 
and positive locking characteristics provided by a fixed cam as well as 
the advantages provided by a moving cam in maintaining a locked condition. 
SUMMARY OF THE INVENTION 
According to one aspect of the present invention, in the clutch of the type 
having concentric and spaced apart driving and driven members with a 
clutch ring in engagement with one of the members and urgeable into a 
simultaneous engagement with the other member, the improvement comprises a 
fixed cam member nonrotational with respect to the driving and driven 
members. A second cam member is slidably movable around the first cam 
member whenever the clutch ring is in simultaneous engagement with the 
driving and driven members. A cam follower is in a cammed engagement with 
the first cam member and is movable axially apart from the first cam 
member into a cammed engagement with the second cam member. The cam 
follower further urges the clutch ring into a simultaneous engagement with 
the driving and driven member whenever the driving member rotates with 
respect to the driven member. 
It is an object of the present invention to provide a locking clutch having 
a sliding clutch ring effecting hub lockup in a quick and positive manner. 
It is a further object of the present invention to provide a locking clutch 
initially effecting clutch lockup with a fixed cam member. 
A still further object of the present invention is to provide a locking 
clutch utilizing a moving cam member to maintain clutch lockup. 
The foregoing, and other objects, features, and advantages of the present 
invention will become more apparent in light of the detailed description 
of the preferred embodiment thereof set forth hereafter, and illustrated 
in the accompanying drawings.

BEST MODE OF CARRYING OUT THE INVENTION 
The locking clutch of the present invention is of the type having 
concentric and spaced apart driving and driven members with a clutch ring 
being in engagement with one of the members and urgeable into a 
simultaneous engagement with the other member. With reference to FIGS. 1 
and 6, the improvement in this type of clutch comprises a fixed or first 
cam member 20 nonrotatable with respect to both the vehicle's driving and 
driven members. A second or moving cam member 30 is movable around the 
first cam member whenever the clutch ring 40 is in simultaneous engagement 
with the driving and driven members. A cam follower 50 is in a cammed 
engagement with the first cam member and is movable axially apart from the 
first cam member and into a cammed engagement with the second cam member. 
The cam follower further urges the clutch ring to a simultaneous 
engagement with the driving and driven member whenever the driving member 
rotates with respect to a driven member. These and other members 
comprising the locking clutch of the present invention will next be 
described below in more detail. 
With reference to FIGS. 2, 3, the clutch of the present invention is 
generally disposed between a vehicle's concentric and spaced apart driving 
and driven members. The vehicle driving member, typically a vehicle axle 
shaft, is in splined engagement with both a first hub axle shaft 14 and a 
second hub axle shaft 16. The first and second hub axle shafts axially 
abut each other along the length of the vehicle axle shaft with the second 
hub axle shaft adapted to be axially displaceable along the vehicle axle 
shaft as will be discussed more fully below. The first hub axle shaft 
carries a plurality of splines 15 disposed circumferentially around its 
outside surface extending axially along its length. The second hub axle 
shaft carries a plurality of splines 17 disposed circumferentially around 
its outside surface with the splines extending axially along a portion of 
its length. As shown in FIG. 1, splines 15, 17 are nonalignable with each 
other preventing the cam follower from being urged from the first hub axle 
shaft onto and into engagement with the second hub axle shaft. The first 
hub axle shaft further carries a retaining ring 18 (see FIGS. 2, 3) 
disposed circumferentially around one end securely engaging the first said 
axle shaft to the vehicle axle shaft. 
Disposed between the driving and driven members is a slidable clutch ring 
40 carried by one of the members. As shown in FIG. 1, the clutch ring has 
a plurality of splines 41 disposed circumferentially around its outside 
surface extending axially along the length of the clutch ring. These 
splines are in a splined engagement with a plurality of complementary 
splines 42 disposed along the inside surface of the hub body 43. Disposed 
circumferentially along the inside surface of the clutch ring are a 
plurality of splines 44 urgeable into a simultaneous splined engagement 
with the splines 17 carried on the second hub axle shaft. In this manner, 
when the clutch ring is axially displaced by movement of the cam follower 
as will be described, the clutch ring becomes simultaneously engaged to 
the vehicle's axle shaft and to the hub body, thereby effecting clutch 
lockup. 
A cam follower 50 is disposed adjacent the clutch ring and abuts one end of 
the clutch ring. The cam follower has a plurality of splines 51 disposed 
circumferentially around its inside surface in splined engagement with the 
plurality of splines 15 carried on the first hub axle shaft. The cam 
follower has a plurality of cam surfaces 52 engageable with a 
corresponding plurality of cam surfaces carried by the fixed cam. 
Extending radially upwardly from each cam surface is a tooth 53 for 
engagement with the plurality of cammed surfaces carried on the moving cam 
as will be described in more detail below. 
The fixed cam carrying a plurality of cam surfaces 21 circumferentially 
disposed around its outside surface, abuts and is nonrotatably secured to 
a portion of the vehicle, such as the vehicle's spindle lock nut 23 or the 
like. The spindle lock nut is spaced apart from both the hub body and the 
hub axle shaft. The fixed cam has a lock tab (not shown) extending axially 
outwardly from the face of the fixed cam abutting the spindle lock used to 
engage and secure the fixed cam to the spindle lock nut. 
A moving cam 30 in slidable engagement with the spindle lock nut 23 carries 
a plurality of cam surfaces 31 circumferentially around its inside 
surface. The moving cam extends axially outwardly around the fixed cam as 
well as the cam follower. Disposed at one end of the moving cam and within 
a plurality of openings (not shown) are a plurality of drag shoes 32 in 
slidable engagement with the spindle lock nut. The drag shoes are 
maintained within the openings by a spring 33 circumferentially disposed 
around the outside surface of the moving cam. 
Two wheel drive mode. 
With reference to FIGS. 2-5, the operation of the present invention in the 
free run or two wheel drive mode will next be described. In the two wheel 
drive mode, the cam follower 50 abuts the fixed cam 20, with the plurality 
of cam surfaces 52 carried on the cam follower in engagement with the 
plurality of cam surfaces 21 carried by the fixed cam (see FIG. 4). In 
this configuration, the moving cam extends around and axially outwardly 
from both the fixed cam and the cam follower. In this mode, the vehicle's 
axle shaft, the first hub axle shaft 14, and second hub axle shaft 16 are 
nonrotational with respect to the vehicle's hub and vehicle hub body 43. 
The slidable clutch ring 40 is urged axially toward the cam follower by 
spring 45 and is prevented from effecting a simultaneous engagement with 
the second hub axle shaft by the spring. The clutch ring, being splined to 
the hub body, rotates at a rotational speed equivalent to that of the 
vehicle hub. Relative motion occurs between the cam follower and the 
clutch ring along bearing washer 48 (see FIGS. 1, 2). In the two wheel 
drive mode, relative motion between the cam follower and clutch ring 
produces torque, but in that the operation of the present invention in 
this mode is substantially a fixed cam type arrangement, the torque 
generated by this relative motion is insufficient to cause the cam 
surfaces 52 cammed by the cam follower to move relative to the cam 
surfaces 21 carried by the fixed cam. As such, the clutch ring is not 
axially displaced into a simultaneous splined engagement with the hub body 
and the axle shaft. 
Lockup Mode. 
With reference to FIGS. 3-5, the operation of the present invention in the 
lockup mode of four wheel drive mode will next be described. In this mode, 
both the vehicle's axle shaft and the vehicle hub body are rotational with 
respect to each other. As the vehicle's axle shaft begins to rotate, the 
first hub axle shaft 14 and the second hub axle shaft 16 both being 
splined to the vehicle's axle shaft begin to rotate. The cam follower 50 
being splined to the first hub axle shaft also begins to rotate. Since the 
fixed cam is secured to the spindle lock nut, it is prevented from 
rotation, consequently the plurality of cam surfaces 52 carried on the cam 
follower begin to move along the plurality of cam surfaces 21 carried by 
the fixed cam. This movement axially displaces the cam follower along the 
splines 15 carried by the first hub axle shaft. The axial displacement 
urges the sliding clutch ring axially forwardly compressing the spring 45 
permitting the clutch ring to become simultaneously splined to the 
vehicle's axle shaft (through the second hub axle shaft 14) and the hub 
body 43. As the cam surfaces 52 continue to move with respect to the cam 
surfaces 21, the surfaces axially separate from each other with the teeth 
53 engaging and moving radially along the face 22 on the fixed cam. As the 
teeth 53 move along the face 22, the teeth engage a plurality of cam 
surfaces 31 carried by moving cam 30. When this occurs, the cam follower 
is further displaced away from the fixed cam urging the sliding clutch 
ring into further engagement between the vehicle's axle shaft and hub 
body. The axial movement of the cam follower away from the fixed cam 
continues until the teeth 53 on each cam surface 52 engage a cam stop 34 
carried by the cam surfaces 31. When this occurs, axial movement of the 
cam follower ceases, and the torque generated by the axle shaft is 
sufficient to cause the moving cam 30 to begin to rotate with respect to 
the spindle lock nut. 
In the event the sliding clutch ring is unable to become simultaneously 
engaged to the vehicle's axle shaft, as may occur when the splines 44 
disposed along the inside surface of the clutch ring are misaligned with 
respect to the splines on the second hub axle shaft, the movement of the 
cam follower axially away from the fixed cam and into a cammed engagement 
with the moving cam urges the second hub axle shaft axially away from the 
first hub axle shaft thereby compressing spring 47. This misalignment does 
not prevent the cam follower from engaging the plurality of cam surfaces 
31 carrying the moving cam. When the splines in the clutch ring and the 
second hub axle shaft become aligned with each other, the spring 47 urges 
the second hub axle shaft axially toward the first hub axle shaft so that 
the sliding clutch ring effects a simultaneous engagement between the 
second hub axle shaft and the hub body. At this point in time, the clutch 
is in a locked up condition with the moving cam slidably rotatable about 
the spindle lock nut. 
An alternate embodiment of the present invention is shown in FIGS. 6-9. In 
this embodiment, a hub axle shaft 60 is splined to the vehicle's driving 
member and rotates with the driving member. A fixed or first cam member 20 
is nonrotatable with respect to both the driving member and the vehicle's 
driven member. A second or moving cam member 30 is movable around the 
first cam member whenever the sliding clutch ring 40 is simultaneously 
engaged to the driving and driven members. The clutch ring is axially 
movable within a cage member 70 which is in a splined engagement with the 
clutch ring and rotates therewith. The cam follower 50 is in cam 
engagement with the first cam member, abuts the cage member, and is 
movable axially apart from the first cam member into a cam engagement with 
the second cam member. The cam follower in conjunction with the first and 
second cam members urges the cage member and clutch ring into simultaneous 
engagement with the vehicle's driving and driven members whenever the 
driving member rotates with respect to the driven member. These and other 
features comprising the alternate embodiment of the present invention will 
next be described in more detail. With reference to FIG. 6, a hub and 
shaft 60 is secured to the vehicle's driving member such as by splines or 
the like, and rotates with the driving member. In this embodiment, the hub 
axle shaft replaces the first and second hub axle shafts (see FIGS. 1-3) 
described in the previous embodiment of the present invention. The hub 
axle shaft has a plurality of splines 61, 62 disposed circumferentially 
around the outside surface of the axle shaft at opposite ends of the 
shaft. The plurality of splines extend axially along a length of the axle 
shaft and are spaced apart from each other. Splines 61 are complementary 
to and in splined engagement with a plurality of splines 55 disposed 
circumferentially around the inside surface of the cam follower 50. As 
will be described below, the cam follower is displaceable axially along 
these splines whenever the vehicle's driving member rotates with respect 
to the driven member. Splines 62 are complementary to a plurality of 
splines 48 disposed circumferentially around the inside surface of the 
sliding clutch ring 40, and urgeable into engagement with each other 
whenever the present invention is in the lockup mode. The hub axle shaft 
is prevented from axial movement along the driving member by the axle 
extender 90. 
The sliding clutch ring 40 is axially movable within a cage member 70. The 
cage member has a plurality of guide arms 71 extending axially outwardly 
therefrom in splined engagement with the plurality of splines 41 disposed 
circumferentially around the outside surface of the clutch ring. In this 
manner, the clutch ring is axially movable along the guide arms to effect 
clutch lockup. A cage cap 72 is snap fitted to the plurality of guide 
arms, abuts the clutch ring and ensures the clutch ring is maintained 
within the cage as it axially moves therein. A spring 80 urges the clutch 
ring into simultaneous splined engagement between the driving and driven 
members whenever the plurality of splines 48, 62 on the clutch ring and 
hub axle shaft respectively are aligned with respect to each other as will 
be described below. The spring is preloaded to ensure the clutch ring is 
returned to its initial position within the cage when the clutch makes a 
transition from the lockup mode to the two wheel drive mode. 
The wheel hub axle shaft is in splined engagement with the driving member 
and is secured thereto by an axle extender 90. The axle extender is 
screwably secured to one end of the driving member. The axle extender has 
a head 91 having a diameter substantially the same as the outside diameter 
of the driving member. The head has a plurality of splines 92 
circumferentially disposed therearound which are complementary to the 
splines disposed within the inside surface of the hub axle shaft. In this 
manner, when the axle extender is screwably secured into one end of the 
driving member with the splines on the axle extender and driving member 
aligned with respect to each other, the hub axle shaft is slidably urged 
into engagement with the driving member and a portion of the axle extender 
(see FIGS. 7, 8). A retaining ring 93 is disposed circumferentially around 
the head of the axle extender, abuts one end of the hub axle shaft and 
further secures the axle shaft from axial movement along the driving 
member. With reference to FIGS. 7-8, a hub extender 95 having a needle 
bearing 96 therearound is secured to the axle extender and provides a 
means with which to attach the clutch cap 46. The fixed or first cam 
member 20, the second or moving cam member 30, and the cam follower 50 
have been described with respect to the previous embodiment of the present 
invention. The operational details of these members, together with the 
other members comprising the alternate embodiment of the present 
invention, can best be understood with reference to a description of the 
operation of the alternate embodiment which next follows. 
Two Wheel Drive Mode. 
With reference to FIGS. 6-7, in the two wheel drive mode, the vehicle's 
driving member is nonrotatable with respect to the vehicle's driven 
member. In this mode, the clutch ring being splined to the inside surface 
of the driven member rotates with respect to the driving member. The cage 
member 70, and the cage cap 72 being splined to the clutch ring similarly 
rotate with respect to the driving member. The cage member abuts the cam 
follower, and rotates with respect to the cam follower. The rotational 
movement of the cage member along the cam follower creates a torque which 
is not sufficient to cause the cam surfaces 52 on the cam follower to move 
with respect to the cam surfaces 21 on the fixed cam 20. As a result, the 
cam follower is not axially displaced along the hub axle shaft and the 
switch ring is not axially displaced into simultaneous engagement with the 
driving member. 
Lockup Mode. 
With reference to FIGS. 6 and 8, in the four wheel drive mode, the 
vehicle's driving member is rotatable with respect to the driven member. 
When this occurs, the relative rotational movement causes the cam follower 
to become axially displaced with respect to the cam member 20 as has been 
described. This axial movement axially displaces the cage member, and the 
sliding clutch ring causing splines 48 within the inside surface of the 
clutch ring to engage the splines 62 on the outside surface of the hub 
axle shaft. If the splines are aligned with respect to each other, further 
movement of the cam follower urges the clutch ring into simultaneous 
engagement between the vehicle's driving and driven members. In the event 
the splines on the clutch ring and the hub axle shaft are not aligned with 
respect to each other, further movement of the cam follower urges the cage 
member axially toward the clutch ring compressing springs 80 and 82. At 
such time the splines on the clutch ring and the hub axle shaft become 
aligned, the spring urges the clutch ring into simultaneous engagement 
between the driving and driven members thus effecting clutch lockup.