Automatic clutch assembly

A locking gear in the form of an annular, slotted cam member causes a driving member to move into locking engagement with a member to be driven automatically in response to the application of torque or positive rotation to the driving member. The driving member can be disengaged only by removing torque from the driving member and reversing the direction of rotation of the driven member without relying upon spring force for disengagement. Accordingly, the driving member is not only forcefully cammed into engagement with the member to be driven but is mechanically and positively cammed into disengagement at the will and under the full control of the operator. Thus in four-wheel drive vehicles, the wheels or members to be driven are selectively engaged by a drive gear which is slidably advanced through interengagement of cam followers on the drive gear with camming surfaces on the locking gear. In one form, the camming surfaces may be inner and outer concentric cam surfaces which cooperate to simultaneously control the axial displacement of the driving member into engagement with the member to be driven and to positively cam the driving member in a return direction away from engagement with the member to be driven when torque is no longer applied to the driving member and the member to be driven is reversed in rotation.

BACKGROUND OF THE INVENTION 
Mechanical clutch assemblies are customarily employed between rotatable 
drive and driven members to establish selective engagement between the 
members when torque is applied to the drive member. A typical application 
is in four-wheel drive controls for vehicles so as to permit selective 
engagement and disengagement of the drive axle with respect to the front 
wheels in converting between a two-wheel drive and four-wheel drive. In 
the past, numerous clutch mechanisms have been devised for this and other 
applications but have relied to a great extent upon a biasing spring force 
to slidably disengage two intermeshed gears while sliding one of the gears 
along a drive shaft. The adhesion of the interfaced gears and of the 
sliding gear to the drive shaft which is caused by parasitic or latent 
torque, surface conditions of the intermeshed parts, lubrication or the 
lack of same, temperature, dirt, clearances, grease viscosity, parts 
concentricity, burrs, contamination and other conditions have under 
certain conditions interfered with the disengagement of the teeth between 
the intermeshed gears so as to result in serious malfunctioning. In any 
event, clutch mechanisms which rely upon a spring or springs to cause 
quick disengagement between intermeshing gears are functionally limited by 
the environmental conditions within the mechanism. Moreover, the return 
springs in order to possess sufficient force to cause disengagement often 
impose thrust loads upon the axial thrust bearings of the vehicle as well 
as bearings supporting the actuating members so that allowable return 
spring pressures are limited by the construction and parts presently 
employed in vehicular wheel designs. 
One principal problem affecting proper functioning of a clutch mechanism of 
the type described is that of lubricant conditions and specifications. 
Extreme hot or cold temperatures will cause standard lubricants to congeal 
or nearly solidify. Moreover, once a vehicle is in the hands of an owner 
there is no assurance that the proper lubricants will be employed. Another 
problem occurs when the vehicle wheels are turned before or during the 
attempt to disengage the clutch mechanism to impart a substantial cocking 
pressure to the interfaced gears and the interface between the axle spline 
and gear thereby requiring increased force to disengage the parts. 
Another requirement for four wheel drive vehicles is for all four wheels to 
remain engaged with the power train even during a steep or sudden descent. 
It is therefore desirable to provide a clutch mechanism which is capable 
of positive engagement and disengagement under the control of the vehicle 
operator without being affected by the aforestated and other known 
environmental or operating conditions and further will not impose unduly 
heavy loads on any of the thrust bearings employed within the clutch 
mechanism or vehicle. 
Representative patents which disclose clutch mechanisms for four wheel 
drives are my U.S. Pat. No. 3,217,845; 3,442,361 to Hegar; and 3,656,598 
to Goble. Examples of ball and cam arrangements employed in a clutch 
mechanism to obtain axial movement in response to the application of 
torque is shown in U.S. Pat. No. 3,829,147. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide for a novel 
and improved mechanical clutch which is highly reliable and dependable in 
operation; and wherein drive and driven members are capable of being 
positively cammed into and out of engagement under the full control of an 
operator. 
Another object of the present invention is to provide for a novel and 
improved automatic clutch assembly made up of a minimum number of parts 
which are movable over a predetermined distance to effect positive 
engagement and disengagement between drive and driven members. 
A further object of the present invention is to provide in an automatic 
mechanical clutch mechanism for positive engagement and disengagement 
between the clutch members while avoiding complete dependence upon a 
return spring or other less positive forms of pressure for disengaging the 
clutch members. 
An additional object of the present invention is to provide in an automatic 
clutch assembly for a single element capable of effecting all of the 
necessary movements between the actuating members to bring about 
engagement or disengagement between the principal drive and driven 
members. 
It is still a further object of the present invention to provide in a 
four-wheel drive vehicle for an automatic clutch assembly which permits 
remote but positive control over the clutch assembly to shift the vehicle 
into four-wheel drive by application of torque to the drive axle or out of 
four-wheel drive by removal of torque and reverse rotation or turning of 
the driven member through less than a complete revolution and wherein the 
clutch assembly is capable of automatically engaging or disengaging either 
in the forward or reverse direction of the motor vehicle. 
Another object of this invention is to prevent damage to the actuating 
parts and gears as well as the vehicle drive train components when 
abnormal or abusive sudden torque is applied in the course of engagement 
or disengagement of the driven and receiving gears; and further to limit 
axle drift during vehicle operation in four-wheel drives and to more 
positively relocate the drive axle while shifting into four-wheel drive 
should the axle have incurred any minor drift when disengaged. 
In accordance with the present invention, a locking gear or cam causes a 
drive member to engage a driven member in response to the application of 
torque or positive rotation to the drive member. When torque is removed, 
the drive member can be disengaged only by reversing the direction of 
rotation of the drive member whereupon the locking gear will positively 
cam or return the drive member to its disengaged position without relying 
upon spring force. Specifically, the positive selective engagement and 
release as described is accomplished through the cooperation of the 
locking gear with a cam follower or followers on the drive member, each 
follower protruding through a pair of cooperating slots in inner and outer 
concentric ring-like cam members which define the locking gear. Each slot 
is provided with a cam surface configured such that rotation of the drive 
member will cause each follower or drive pin to advance in an outward 
axial direction along that cam surface thereby imparting axial movement to 
the drive member so as to cause it to move into engagement with the member 
to be driven; and a second cam surface in each slot is so configured and 
positioned that it will be engaged by the follower to force its associated 
cam ring away from its normally locked position with a fixed member. A 
third cam surface is located preferably in the same slot as the second cam 
surface and is raised along with the second cam surface above the level of 
the first cam surface to normally retain the follower in a raised position 
within the first slot irrespective of whether torque is applied to the 
driving member. Accordingly, it is necessary to reverse the rotation of 
the driven member to impart a reverse movement to the follower causing it 
to engage the third cam surface and to drive it in a direction to effect 
re-engagement of the associated cam ring with the fixed member before the 
follower is free to return to its original position and the entire drive 
member is free to slide axially away from the driven member. Accordingly, 
cooperating cam surfaces simultaneously control the axial displacement of 
the follower and associated drive member into and out of engagement with a 
member to be driven. The apparatus described has particular application to 
four-wheel drive vehicles in which the drive member is splined to a drive 
axle and is operative to engage a driven member associated with the wheel 
hub in response to torque applied to the drive axle. The wheel hub is 
engaged by the drive member so long as rotation continues in a given 
direction and notwithstanding resistance torque from the driving member 
and drive train. The drive member also continues to engage the driven 
member after torque is removed from the driving member and regardless of 
drive train resistance so long as the driven member overrides and drives 
the former driving member in the same rotational direction that preceded 
removal of driving torque from the driving member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring in more detail to the drawings, the preferred form of automatic 
clutch assembly is shown by way of illustrative example for use in 
connection with a four-wheel drive vehicle and specifically to control the 
locking and release between a drive axle A and spaced outer concentric 
wheel hub H. One end of the drive axle A is illustrated in FIGS. 1 and 2 
and is provided with external, axially directed splines 10, and an annular 
groove 11 is formed in the external surface of the outer end of the axle 
between the splined portions 10 and outer extremity 12 of the axle. A 
hollow cylindrical spindle S is fixed in spaced outer concentric relation 
to the drive axle, the external surface of the spindle being threaded to 
receive an outboard spindle nut 14, and an inboard spindle lock nut 15 is 
spaced from the nut 14 by a lock washer 16 which is keyed and engaged into 
keyway 40. Nut 15 is spaced from the inner race of a wheel bearing 
represented at B by a spacer washer 17. The wheel hub H is journaled for 
rotation with respect to the spindle S and axle A by the wheel bearing 
assembly B, and an outer cover flange C is secured to the end of the wheel 
hub by a series of circumferentially spaced bolts D so as to enclose the 
entire axle and cam lock assembly. The foregoing description of the wheel 
assembly is intended to provide a setting for the present invention and 
specifically for the purpose of describing the unique manner in which a 
cam lock assembly is interposed between the fixed spindle S, axle A and 
outer concentric wheel hub H. 
The cam lock assembly is generally designated at 20 and in the preferred 
form is broadly comprised of an inner concentric cam lock or ring member 
21 and an outer concentric ring or camming member 22. Members 21 and 22 
have aligned cam slots 23 and 24, respectively, at spaced circumferential 
intervals which are adapted to receive cam follower members 26 projecting 
outwardly from a drive gear 28. The drive gear 28 defines a first 
actuating member which is axially advanced in response to rotation of the 
drive axle A and movement of the cam followers 26 through the cam slots 23 
and 24 in a manner to be described. Axial advancement of the drive gear 28 
in a direction toward the outer extremity of the axle A will cause it to 
move into intermeshing engagement with an outer concentric ring gear 30 
which in turn interengages with the cover flange C to impart rotation of 
the drive axle A through the drive gear 28 and ring gear 30 into the cover 
flange C and attached wheel hub H to impart rotation to the vehicle wheel, 
not shown. When the drive axle A is no longer rotated or driven, the cam 
lock assembly 20 functions to positively retract or withdraw the drive 
gear 28 away from driving engagement with the ring gear, for example, as 
illustrated in FIG. 2. For this purpose, the inner cam lock 21 is provided 
with radially inwardly bent teeth or tab extensions 34 at its inboard 
extremity, and the outer cam 22 is provided with a radially outwardly 
directed flange or lip 35 at its inboard extremity, the teeth 34 and 
flange 35 being associated with a spindle lock 38 and thrust washer 
bearing 42 in a manner now to be described. 
The spindle lock 38 is comprised of a series of axially directed and 
radially inwardly projecting tab extensions 36 which interengage with the 
inwardly directed teeth 34 on the cam lock 21 to lock the cam lock 
assembly 20 against rotation when the assembly 20 is in the disengaged 
position. A series of axially or inwardly directed spring tabs 39 are 
spaced circumferentially toward the outward radial extremity of the 
spindle lock 38 and project into shallow depressions or indents 16' on the 
external edge surface of the lockwasher 16. A radially inwardly projecting 
key 40' on the inner edge surface of lock washer 16 engages keyway 40 in 
spindle S. Another series of inwardly projecting tabs 41 bear against the 
outer annular face of the spindle nut 14 so as to properly center the 
spindle lock 38 with respect to the nut 14. A thrust bearing 42 is 
positioned on the outer face of the spindle lock 38 and is preferably an 
oil/graphite impregnated bronze bearing which has a series of lugs 43 on 
its inboard surface to engage slots 41' found by punching out the tabs 41 
in the lock washer 38 so as to fix the bearing against rotation while 
centering the bearing on the spindle lock. The outboard surface of the 
thrust bearing 42 forms a flat running surface for the flange 35 of the 
outer cam member 22. 
An assembly cup 44 is disposed in surrounding relation to the spindle lock 
38, thrust bearing 42 and flange 35 for the purpose of unitising those 
parts into one assembly and to retain the parts in proper concentric 
relation to the spindle nut 14 and in outer spaced concentric relation to 
the drive axle A. The assembly cup 44 is provided with a plurality of tabs 
44' at its inboard end which are bent inwardly against the inboard surface 
or underside of the spindle lock 38 with suitable clearance provided 
during assembly so as to avoid compressing the parts together and to 
assure that the outer cam member 22 is free to rotate while the thrust 
bearing 42 and spindle lock 38 remain stationary. 
The drive gear 28 is of hollow cylindrical configuration and relatively 
thickwalled. Its inner wall surface is splined as at 50 to intermesh with 
the external spline portions 10 on the axle A. In turn its external 
surface is splined as at 52 to intermeshingly engage with internal teeth 
or spline portions 54 on the ring gear 30. The axial movement of the drive 
gear 28 is controlled by the cam followers 26, each cam follower 26 having 
a pin 56 provided with a serrated tip which is driven radially in 
press-fit engagement into an opening in the body of the drive gear 28 and 
an outer roller 57 journaled on the pin and adapted to project radially 
outwardly from the pin for engagement within the aligned cam slots 23 and 
24 of the cam lock assembly 20. 
The ring gear 30 is operative to impart the rotational driving force of the 
axle A into the outer hub when the drive gear 28 is advanced into 
engagement with the ring gear; and to this end, the ring gear has external 
splined portions 60 extending axially along its external surface and 
interengaging with internal splined portions 61 on the inner wall of the 
cover flange C. The internal splined portions 54 which are selectively 
engaged by the drive gear extend along an inwardly stepped, internal wall 
62 at the inboard or lower end of the ring gear 30. In turn, a shoulder or 
stepped portion 64 is formed at the outer end of the internal splines 54 
to provide a seating surface for one end of a coiled spring 66 which 
extends between the outer end wall of the cover flange C and the seating 
surface 64 to urge the ring gear 30 to an inboard position with the 
external splined portion 60 bearing against a shoulder 68 at the end of 
the splined portion 61 on the cover flange. Another compression spring 70 
is positioned in inner spaced concentric relation to the spring 66 and has 
one end bearing against the end of the drive gear 28 and its opposite or 
outer end is seated within a return flanged portion 72 on the outer end of 
a spring retainer 73 which forms an outward axial extension of the splined 
end portion of the axle A. As illustrated the inner end of spring retainer 
73 has a radially inwardly bent flange or tab 75 which is inserted into 
the annular groove 11 at the outer end of the axle. In this relation, it 
is emphasized that the spring members 66 and 70 function primarily to 
maintain proper spacing between the ring gear and drive gear as well as to 
minimize any rattling or shifting of the parts during operation of the 
vehicle. Thus, other suitable means of alignment could be employed for 
this purpose, such as, magnets since the spring elements described are not 
required to effect engagement or disengagement between the clutch and cam 
members. 
An important feature of the present invention resides in the cooperative 
disposition and relation between the inner and outer cam elements 21 and 
22 and the manner in which they cause the drive gear 28 to be forcibly 
cammed into engagement with the ring gear 30; and further the manner in 
which they cause the drive gear to be positively cammed or drawn away from 
engagement with the ring gear under the full control of the vehicle 
operator and without relying upon the force of the springs 66 and 70. 
Specifically referring to FIG. 3, it will be noted that the inner cam 
member 21 is in the form of a hollow cylindrical, thin-walled sleeve or 
ring member having a series of three generally V-shaped winged cams 23 
formed at equal 120.degree. intervals in the intermediate wall thickness 
of the body of the cam 21. A plurality of downwardly directed open slots 
81 are disposed intermediately between the cams 23, and radially outwardly 
bent tabs 82 are formed out of the wall of the cam adjacent to its upper 
or outboard edge intermediately between the cam slots 23. The inwardly 
directed teeth 34 as previously stated extend inwardly in a radial 
direction from the lower or inboard edge of the cam and are adapted to 
effect engagement with the upwardly bent tab extensions 36 of the spindle 
lock 38. The outer concentric cam lock member 22 is similarly in the form 
of a hollow cylindrical, thin-walled sleeve having a series of three 
generally V-shaped winged slots 24 at equally spaced circumferential 
intervals, or 120.degree. apart, and are formed through the intermediate 
wall thickness of the body of the cam 22. Apertures 86 are formed in the 
member 22 intermediately between the cam slots 24 adjacent to the outboard 
face of flange 35, and upwardly directed open slots 87 are formed 
intermediately between the cam slots 24. In assembled relation when the 
inner cam 21 is placed within the outer cam 22, the outwardly projecting 
tabs 82 are aligned within the slots 87 so as to initially fix the inner 
cam 21 against rotation with respect to the outer cam 22 and in which 
relation the lower open slots 81 are aligned with the apertures 86 to 
receive a connecting pin 88 through each of the respective aligned 
apertures 86 and slots 81 so as to assist in locking the inner cam 21 
against rotation with respect to the outer cam 22 while permitting a 
limited degree of independent axial movement of the inner cam in a manner 
to be hereinafter described. Once the cam members 21 and 22 are aligned, 
each of the three inner cam slots 23 are aligned opposite to a respective 
outer cam slot 24 so as to permit insertion of a cam follower assembly 26. 
Considering in somewhat more detail the configuration of the inner and 
outer cam slots 23 and 24, respectively, it will be noted that the inner 
cam slot 23 is provided with a bottom or inboard horizontal bearing 
surface 90, inclined bearing surfaces 91 diverging at substantially a 
45.degree. angle away from the surface 90 and intersecting a downwardly 
inclined bearing surface 92 at a point 93, the downwardly inclined bearing 
surface 92 inclining at an angle of approximately 20.degree. to horizontal 
away from the point 93. An upper or outboard horizontal bearing surface 94 
is aligned opposite to the bearing surface 90 but is of considerably less 
length than the bearing surface 90; and upper inclined bearing surfaces 95 
diverge away from the bearing surface 94 to intersect downwardly inclined 
bearing surfaces 96 at a point or line 97, the surfaces 96 being spaced 
above the surfaces 92. Vertical surfaces 98 extend between the outer 
lateral edges of the downwardly inclined surfaces 92 and 96 so as to close 
opposite lateral edges of the cam slot. The aligned bearing surfaces on 
the cam slot 24 generally corresponding to those of cam slot 23 are 
enumerated with like prime numerals. Specifically, the upper and lower 
bearing surfaces 94' and 90' together with the inclined surfaces 95' and 
91' are of corresponding construction and related configuration to those 
of the bearing surfaces 94, 90, 95 and 91 in the inner cam 21. However the 
upper and lower bearing surfaces 96' and 92' extend in a horizontal 
direction away from their intersection with the inclined bearing surfaces 
91' and 95', as opposed to the downwardly directed or sloped disposition 
of the surfaces 92 and 96 in the inner cam member. 
The interrelationship between the cam members 21 and 22 and cam follower 26 
can best be appreciated from a consideration of the sequential movement 
between the slots and the cam follower in response to the application or 
removal of torque on the drive axle A. As shown in FIG. 5A, when the 
vehicle is in two-wheel drive and no torque is applied to the drive axle, 
the cam follower 26 will normally be positioned at the bottom of the slots 
23 and 24 between the pairs of bearing surfaces 90, 90' and 94, 94'. 
However, when torque is applied to the drive axle, it will cause the drive 
gear 28 to rotate with the drive axle A in response to which the cam 
follower 26 will according to the direction of rotation of the drive axle 
advance upwardly along one of the inclined surfaces 91' of the outer cam 
lock member 22. In its continued advancement along the horizontal bearing 
surface 92' of the outer cam 22 however it will simultaneously engage the 
upper inclined bearing surface 96 of the inner cam 21 causing the inner 
cam to be lifted away from engagement with the spindle lock 38, the 
movement of the inner cam 21 and follower 26 being illustrated in FIGS. 5B 
and 5C. In response to upward or outward movement of the cam follower 26 
along the inclined bearing surfaces 91 and 91', the drive gear 28 will 
have been axially advanced into engagement with the ring gear 30. FIG. 5C 
illustrates the interrelationship between the cam follower 26 and the cam 
slots 23 and 24 when the follower has been driven to one end of the slots, 
at which point the inner cam 21 has been fully disengaged from the spindle 
lock 38. As long as torque is applied to the drive axle A the cam follower 
26 will remain in this position; and further irrespective of whether 
torque is applied to the drive axle, the cam follower will remain in the 
position shown in FIG. 5C until the drive axle is reversed in its 
direction of rotation. Thus it is necessary to bring the vehicle to a 
complete stop and to reverse the rotation of the drive axle in order to 
initiate disengagement of the drive gear 28 from the ring gear 30. 
FIG. 5D illustrates initial return movement of the cam follower 26 in 
causing the drive gear to be axially retracted away from the ring gear and 
in returning the inner cam lock member 21 into engagement with the spindle 
lock 38. FIG. 5E illustrates the relative position of the cam slots 23 and 
24 and cam follower 26, specifically in returning the bearing surfaces 95 
and 96 to their original position, with bearing surfaces 96 and 92 
slightly offset beneath the bearing surfaces 96' and 92' of the outer cam 
member 22. Again in disengaging the clutch or returning to a two-wheel 
drive position, the inner cam 21 will re-engage the extension tabs 39 on 
the spindle lock 38, enabling the drive gear 28 to be retracted away from 
the ring gear and returned to its original position as shown in FIG. 2. 
When the cam follower is retracting gear 28 from gear 30 while progressing 
along cam face 95' of outer cam 22, the total actuator assembly 20 is 
prevented from moving outwardly by the abutment of face 45 of assembly cup 
44 against the face 46 of the cover flange C. In returning the vehicle to 
the two-wheel drive position, it is only necessary to rotate the drive 
axle in reverse over a very limited interval necessary for the drive gear 
to become disengaged from the ring gear 30. The return springs 66 and 70 
will assist somewhat in driving the cam follower 26 to its lowermost 
position between the intermediate bearing surfaces 90' and 94'; also, they 
will urge each cam follower 26 away from an upper bearing surface 95' and 
against the lower bearing surface 91' causing the cam member to be forced 
to the right, until the cam follower has been seated once again on the 
lower bearing surface 90'. 
The difference in the tooth width of teeth 34 of cam lock 21 and the space 
between the tabs 36 of spindle lock 38 is intentionally constructed to 
provide a backlash greater than required to reversely rotate the cams 21 
and 22 allowing cam follower 26 to seek and abut cam face 90' after gears 
30 and 28 have separated and axle A is no longer driven in a reversed 
direction. 
In further explanation referring to FIG. 5D, as cam follower strikes the 
inclined cam face 95' the teeth 34 which have engaged the tabs 36 are 
applying force in a leftward direction as viewed in FIG. 5D. When gears 30 
and 28 separate, cam follower 26 is nearing the inboard end of slope cam 
face 95'. At the moment of disengagement spring 70 urges drive gear 28 
inwardly and cam followers 26 inwardly whereby cam followers 26 drop from 
inclined face 95' to near the bottom of inclined face 91'. Because of the 
predescribed backlash between teeth 34 and tabs 36 the cams 21 and 22 can 
now rotate to the right allowing cam follower 26 to drop to cam face 90' 
without rotation of drive gear 28 and axle A. 
In actual practice, when the vehicle is in two-wheel drive, the cam 
follower 26 is normally located on the lower bearing surface as described. 
Four-wheel drive vehicles typically have a shift lever into a transfer 
case which enables the operator to apply engine power and torque to the 
front end mechanism of the vehicle or to disengage power from the front 
end drive mechanism. Thus when the vehicle is in a two-wheel drive 
position, the cam members 21 and 22 are keyed to one another as described 
with the inner cam member 21 capable of limited slidable movement axially 
with respect to the outer cam 22 but neither can rotate independently of 
the other. Of course as long as the inner cam 21 is locked to the spindle 
lock 38, neither of the cam members is capable of rotating until the inner 
cam 21 is released from engagement with the spindle lock. When the vehicle 
is shifted to four-wheel drive, for example, by shifting the transfer case 
lever to apply torque and power to the drive axle A, the drive gear will 
rotate along with the drive axle. Rotation of the drive gear will force 
the cam followers 26 along the inclined bearing surfaces of the 
cooperating cam slots until the drive gear has been driven axially to a 
position of full engagement with the ring gear 30. In the event that the 
teeth of the drive gear 28 do not immediately engage the inner splined 
teeth of the ring gear 30, the ring gear 30 is capable of sliding 
outwardly against the return spring 66 but will snap back into engagement 
with the drive gear 28 once the teeth are properly aligned. Continued 
rotation forces the inner cam member 21 outwardly away from engagement 
with the spindle lock 38 so that the inner and outer cam members 21 and 22 
are then free to rotate with the drive gear as the drive gear imparts the 
rotational force of the drive axle through the ring gear and cover flange 
into the wheel hub and wheel. In the course of engagement between the 
drive gear and ring gear, the inner spring 70 is compressed against the 
end of the spring retainer 73 and therefore will continue to exert a force 
on the drive gear. When compressed, the smaller diameter inboard coils of 
the spring 70 will encircle and encapsulate the inboard section of the 
spring retainer 73 so as to limit the diametric expansion of the retainer 
causing the flange 75 to remain engaged into groove 11 of axle A when 
thrust loads are placed on the inboard face of the retainer. When the 
drive gear 28 has been driven to its outboard axial location, the outboard 
face 51 of drive gear 28 is located in predetermined spaced relationship 
to flange 75 of retainer 73 and groove 11 of axle A and drive gear 28 now 
provides a positive stop to prevent the drive axle from being drawn 
inwardly when the wheels are turned in either direction while in 
four-wheel drive. 
In order to disengage the clutch assembly, as stated, the vehicle driver 
must first shift the vehicle drive transfer case to the two-wheel drive 
position in order to disconnect the power train and power from the axle A; 
and secondly the vehicle must be reversed in direction so that the vehicle 
hub H will drive the cover flange C and ring gear 30 in a reverse 
direction. Thus the ring gear in effect becomes the driving gear to impart 
reverse rotation to the drive gear 28 and cam follower 26. It will be 
noted that in the process of disengagement as described, the inner splined 
portion of the ring gear 30 engages only a limited section of the 
externally splined teeth of the drive gear 28. As the cam followers 26 are 
forcibly disengaging the drive gear from the ring gear, the frictional 
adhesion of the splines between the drive and ring gears will decrease 
proportionally as the drive gear slides away from engagement with the ring 
gear and toward complete disengagement. At the moment of disengagement the 
compression of the spring 70 in applying pressure against the drive gear 
28, will cause the cam followers 26 to move against the lower bearing 
surfaces 90 and 90' of each of the cam slots while urging the drive gear 
completely away from the ring gear. 
In the preferred form and for the purpose of illustration, the cam members 
21 and 22 are illustrated as having a series of three slots which operate 
in combination with three cam followers 26 on the drive gear. It will be 
evident however that the specific construction and relationship between 
the cam slots and cam followers may be varied depending upon the intended 
application of the clutch assembly and the size of the other parts. 
Moreover it will be apparent that the interrelationship between the cam 
slots and cam followers may be varied where for example a single cam 
member would be employed in cooperation with two or more cam followers. 
For instance, one of the cam followers would advance along a cam slot in 
the cam corresponding to one of the slots in the outer cam member and 
another of the cam followers would work in cooperation with a slot 
corresponding to that of the inner cam ring. Additionally the concentric 
relationship between the driving cam and the camlock can be changed 
wherein the inner cam becomes the outer cam and vice versa by relocating 
the spindlelock tabs radially outward and moving the thrust bearing 
radially inward. 
Another example of an alternate form of cam slot configuration is shown in 
FIGS. 6A and 6B wherein the vertical distance between slope cam faces 91" 
and 95" is greater inboard than outboard at the cam wings 92" and 96" so 
as to effect a straight axial movement of cam follower 26 from cam face 
95" directly to cam face 90" without further driven reverse rotation of 
drive gear 28 at the moment of disengagement of gear 28 from gear 30. 
Stated another way, outboard face 95" has a gentler slope than in the 
preferred form to diverge away from inboard slope 91" to position 90" 
under the point of disengagement of the follower 26 from face 95". 
Although the present invention has been described with particularity 
relative to the foregoing detailed description of the preferred 
embodiment, various modifications, changes, additions and applications 
other than those specifically mentioned herein will be readily apparent to 
those having normal skill in the art without departing from the spirit and 
scope of the present invention.