Blocked jaw clutch assembly

A blocked jaw clutch assembly (156) of the type having sensor unblocking ramps (176, 178, 180, 182) is provided with structure tending to cause the blocking torque friction surface (188) carried by the blocker ring (124) to frictionally engage the blocking torque friction member (190) carried by the first jaw clutch member (108, 164, 188) with a circumferentially non-symetrical axial force.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to blocked jaw clutch assemblies and to 
transmissions utilizing same and in particular to improved blocked jaw 
clutch assemblies for use in compound transmission wherein at least one 
transmission section utilizes blocked resiliently shifted jaw clutch 
assemblies wherein the blockers and associated clutch members in the 
auxiliary section have complementary ramps on the blocking members thereof 
configured to prevent nonsynchronized engagement of the associated jaw 
clutch members when the inertia on one of the clutch members exceeds a 
predetermined limit, such as when one of the other transmissions sections 
is engaged but which will tend to act as positioners to place the blocker 
and clutch member in a nonblocking condition when the inertia on the one 
clutch member is relatively low, such as when one or more of the other 
sections are in a neutral or disengaged condition. 
2. Description of the Prior Art 
Compound transmissions of the splitter or range type, or a combination 
thereof, are well known in the prior art as may be seen by reference to 
U.S. Pat. Nos. 3,105,395; 3,648,546; 3,799,002; 2,932,988 and 3,229,551, 
the disclosures of which are all hereby incorporated by reference. 
Blocked change gear transmissions of both the single and the compound types 
are also well known in the prior art as may be seen by reference to U.S. 
Pat. Nos. 3,799,002; 3,921,469; 3,924,484; 3,983,979; 4,132,122; 4,192,196 
and 4,194,410, the disclosures of which are all hereby incorporated by 
reference. 
Semi-blocked compound change gear transmissions wherein the main section 
utilizes manually engaged nonsynchronized, unblocked jaw clutches to 
selectively engage a selected main section ratio gear and wherein the 
auxiliary section utilizes blocked resiliently shifted jaw clutches to 
selectively engage a selected auxiliary ratio, and wherein the blockers 
(also called sensors) and associated clutch members in the auxiliary 
section have complementary ramps (also called "sensor unblocked ramps") on 
the blocking members thereof configured to prevent nonsynchronized 
engagement of the associated jaw clutch members when the main section is 
engaged but which will tend to act as positioners to place the blocker and 
clutch member in a nonblocking condition when the main section is in a 
neutral or disengaged condition are known in the prior art as may be seen 
by reference to U.S. Pat. No. 4,440,037 and European Publication No. 0 071 
353, published Feb. 9, 1983, of allowed European Patent Application No. 82 
303 585.2 (corresponding to applicant's assignee's U.S. patent application 
Ser. No. 287,470, filed July 27, 1981), the disclosures of which are 
hereby incorporated by reference. 
Automated and/or semi-automated blocked or semi-blocked change gear 
transmissions are known in the prior art as may be seen by reference to 
U.S. Pat. No. 4,527,447, the disclosure of which is hereby incorporated by 
reference. 
The prior art semi-blocked compound transmissions, especially the splitter 
type, wherein the main transmission section is provided with well known 
nonsynchronized, unblocked jaw clutch assemblies, and the auxiliary 
transmission section is provided with resiliently shiftable blocked jaw 
clutch assemblies and, preferably, the blocked jaw clutch assemblies are 
provided with complimentary ramp members on the associated blocker and 
clutch members which will cause the blockers to prevent nonsynchronous 
engagement of the associated jaw clutch assemblies when the main 
transmission section is engaged but will allow the blocker to tend to 
rotationally move to a nonblocking position under the influence of a 
spring bias, when the main transmission section is in neutral, provides a 
relatively uncomplicated and reliable compound transmission which is 
shiftable with substantially the ease of a simple transmission and allows 
shifts to be completed with the vehicle in a static condition. 
The blocked jaw clutch assemblies utilized in such transmissions are 
required to perform two distinct tasks, namely maintain a blocked 
condition under certain non-synchronous and relatively high inertia 
conditions and to unblock, by causing a synchronous condition to occur, 
regardless of the initial relative rotational speeds of the clutch 
members, under certain relatively low inertia conditions. Under certain 
adverse conditions, the ramped, blocked jaw clutch assemblies of prior art 
tended to unblock at improper conditions resulting in the blockers ceasing 
to prevent a nonsynchronous or crash type jaw clutch engagement, which is 
undesirable. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the drawbacks of the prior art 
have been overcome or minimized by the provision of an improved blocked 
clutch assembly utilizing sensor unblocking ramps wherein the tendency of 
the blockers or sensors to move to an unblocking condition under improper 
(i.e. non-synchronous relatively high inertia) conditions is minimized or 
eliminated while retaining the ability of the ramps to cause the blockers 
to move to an unblocked condition under proper (i.e. relatively low 
inertia) conditions. 
The above is accomplished in one embodiment of the present invention by 
providing a plurality of arrays of blocking projections or teeth 
configured such that, at initial engagement of the blocker and clutch 
member, the resulting axial forces exerted between the blocker and 
contacted jaw clutch member are circumferentially non-symmetrical about 
the axes of rotation thereof sufficient to cause an initial relative 
tilting between the blocker and jaw clutch and/or relative radial 
displacement of the blocker ring and clutch members and/or localized 
contact between the blocking torque friction surfaces. 
The above may be accomplished by a multitude of structural modifications. 
By way of example, the arrays may be spaced circumferentially 
non-symmetrical about the axis of the blocker and/or clutch, or the 
pre-energizer ring may be non-symmetrically mounted in the blocker ring; 
or a non-symmetrical pre-energizer ring may be utilized and/or the 
blocking projections at one or more arrays may be axially offset and/or 
eliminated. 
The above improved structure has proven very satisfactory in tests and is 
believed to prevent improper unblocking because the nonsymmetrical contact 
of the blocking torque friction surfaces and/or relative tilting and/or 
radial displacement of the members results in an initial breakdown of the 
oil film on the blocking torque friction surfaces and thus, by creating a 
non-hydrodynamic bearing surface, allows an early establishment of 
blocking torque. Also, a relatively small friction force in a radial 
direction between the members, caused by the unbalanced radial components 
of the non-symmetrical forces acting on cone friction surfaces, may act in 
opposition to any premature unblocking force generated by the unblocking 
ramps. Briefly the invention is believed to provide the observed 
advantages by assuring that the blocking torque caused by the frictional 
engagement of cone surfaces on the blocker and first clutch member, which 
torque causes the blocker to tend to rotate with the first clutch member 
and thus properly clock relative to the second clutch member, is 
established at or prior to the time the ramp surfaces are urged into 
contact at initiation of a clutch engaging operation. 
Accordingly, it is an object of the present invention to provide an 
improved blocked jaw clutch assembly of the type utilizing sensor 
unblocking ramps. 
This and other objects and advantages of the present invention will become 
apparent from a reading of the detailed description of the preferred 
embodiment taken in view of the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the apparatus in detail, it will be recognized that a 
detailed disclosure of both the construction and operation of blockers and 
blocked or semi-transmissions utilizing same has been set forth and 
claimed in the above mentioned patents and reference is therefore made 
thereto for such details. 
Certain terminology will be used in the following description for 
convenience in reference only and will not be limiting. The words 
"upwardly", "downwardly", "rightwardly" and "leftwardly" will designate 
directions in the drawings to which reference is made. The words "forward" 
and "rearward" will refer respectively to the front and rear ends of the 
transmission as same is conventionally mounted in the vehicle, being 
respectively the left and right sides of the transmission as illustrated 
in FIG. 1. The words "inwardly" and "outwardly" will refer to directions 
toward and away from, respectively, the geometric center of the device and 
designated part thereof. Said terminology will include the words above 
specifically mentioned, derivatives thereof and words of similar import. 
The term "compound transmission" is used to designate a transmission having 
a main transmission portion and an auxiliary transmission portion 
connected in series whereby the selected gear reduction in the main 
transmission portion may be compounded by further selected gear reduction 
in the auxiliary transmission port. The term "splitter type compound 
transmission" as used herein will designate a compound transmission 
wherein the auxiliary transmission is used to provide various selectable 
steps or subdivisions of the gear ratio selected in the main transmission 
port. In a splitter type compound transmission, the main transmission 
section is typically provided with relatively wide steps which are split 
or subdivided by the auxiliary section. The term "upshift" as used herein 
shall mean the shifting from a lower speed gear ratio to a higher speed 
gear ratio. The term "downwardly" as used herein shall mean the shifting 
from a higher speed gear ratio to a lower speed gear ratio. The terms "low 
speed gear", "low gear" and/or "first gear" as used herein shall all 
designate the gear ratio. 
The term "blocked transmission" or "blocked transmission section" shall 
designate a change gear transmission or transmission section wherein a 
selected gear is nonrotatably coupled to a shaft by means of a positive 
clutch and a blocker is utilized to prevent such engagement until the 
members of the positive clutch are substantially synchronous, such 
synchronous condition achieved by manual and/or automatic manipulation of 
the transmission input and/or output shafts to cause a crossing of 
syncronous condition therebetween but not achieved by frictional contact 
of the selected clutch members sufficient to cause one of the clutch 
members, and the apparatus associated therewith, to rotate with the other 
clutch member. 
The term "synchronized transmission" shall designate a change gear 
transmission wherein a selected gear is non-rotatably coupled to a shaft 
by means of a positive clutch, attempted engagement of said clutch is 
prevented until the members of the clutch are synchronous and frictional 
means associated with the clutch members are sufficient, upon initiation 
of a clutch engagement, to cause the clutch members, and all members 
rotating therewith, to rotate at a substantially synchronous speed of 
rotation. 
Referring now to FIGS. 1-3, there is illustrated a "4.times.3" twelve 
forward speed, semi-blocked, splitter type compound transmission 10. 
Transmission 10 comprises a main section 12 connected in series with an 
auxiliary section 14, each of which have a plurality of selectable speeds, 
or power paths. The main and auxiliary sections are both suitably enclosed 
by conventional housing means 16. While the blocked jaw clutch assemblies 
with sensor unblocking ramps of the present invention are especially well 
suited for use in connection with semi-blocked transmissions such as 
illustrated transmission 10, the assemblies are also advantageously 
utilized with other types of compound transmissions. 
The transmission 10 includes an input shaft 18 supported adjacent its 
rearward end by a bearing 20 and is provided with an input gear 22 
nonrotatably connected thereto, as by splines. The input gear 22 
simultaneously drives a plurality of main section countershafts at equal 
speeds. In the illustrated embodiment, the transmission is provided with 
two main section countershafts, 24 and 26, disposed on diametrically 
opposite sides of the mainshaft 28, which mainshaft is coaxially aligned 
with the input shaft 18 and is provided with a pilot portion 30 on its 
forward end rotatably received within and supported by the rearward end of 
the input shaft 18. 
The input shaft 18 is normally driven in one direction only by a 
primemover, such as a throttle controlled Diesel engine E through a 
selectively operated, normally engaged, friction master clutch C. Clutch C 
may be selectively disengaged by use of pedal P as is known in the prior 
art. Clutch C may have a known clutch-brake associated therewith. 
Each of the main section countershafts 24 and 26 is provided with an 
identical grouping of countershaft gears, such as the pair of gears 36, of 
identical size and number of teeth and disposed on diametrically opposite 
sides of the mainshaft 28. As may be seen by reference to FIG. 2, 
countershaft gears 42 and 44 may be defined by involute splines formed 
directly on the main section countershafts. 
A plurality of main section mainshaft drive gears 46, 48, 50 and 52 
surround the mainshaft 28 and are selectably clutchable thereto, one at a 
time, by sliding clutch collars as is well known in the art. 
The main section mainshaft gears 46, 48 and 50 encircle the mainshaft 28, 
are in continuous meshing engagement with, and are floatingly supported by 
the diametrically opposite pairs of countershaft gears, 38, 40 and 42, 
respectively, which mounting means and the special advantages resulting 
therefrom are explained in greater detail in U.S. Pat. Nos. 3,105,395 and 
3,335,616, the disclosures of which are hereby incorporated by reference. 
The mainshaft gear 52 is the reverse gear and is in continuous meshing 
engagement with a pair of countershaft gears 44 by means of conventional 
intermediate idler gears (not shown). The forwardmost countershaft gears 
36 are continually meshed with and driven by the input gear 22 for causing 
simultaneous rotation of the countershafts 24 and 26 whenever the input 
shaft is rotatably driven. 
Main section mainshaft gears 46, 48, 50 and 52; and main section 
countershaft gears 36, 38, 40, 42 and 44, and the idler gears, are all 
constantly meshed with and driven by the input gear 22 and thus, in 
combination, form the input gearing of the transmission 10. 
As may be seen, various abutment rings 54 are provided to axially fix the 
main section mainshaft gears relative to mainshaft 28. 
Sliding clutch collars 56, 58 and 60 are splined to mainshaft 28 for axial 
movement relative thereto and rotation therewith as is well known in the 
art. 
Sliding clutch 56 is axially slidable by means of shift fork 62 to clutch 
gear 52 to the mainshaft. Sliding clutch 58 is axially slidable by means 
of shift fork 64 to clutch either gear 50 or 48 to the mainshaft. Sliding 
clutch 60 is axially slidable by means of shift fork 66 to clutch gear 46 
to the mainshaft or to clutch the input gear 22 (and thus the input shaft 
18) to the mainshaft. Shift forks 62, 64 and 66 are attached to shift bars 
or rails, (only one, 68, of which is shown) of a known shift bar housing 
assembly 70 which is operated by a conventional shift lever 72. The 
present invention is also applicable to transmissions utilizing a remote 
mechanical, electrical or fluid shift mechanism in place of shift bar 
housing 70 and shift lever 72 and also to fully or semi-automatic 
transmissions and transmission systems such is that illustrated in U.S. 
Pat. No. 4,361,060. the disclosure of which is hereby incorporated by 
reference. 
Considering now the splitter auxiliary section 14, the mainshaft 28 extends 
thereinto and is coaxially arranged with and piloted into an output shaft 
74 which is in turn supported within the housing 16 by suitable bearings 
generally indicated at 76. Said auxiliary section further includes a 
plurality of auxiliary section countershafts 78 and 80 each having an 
identical grouping of countershaft gears 84, 86 and 88 therein. 
As is known in the art and is illustrated in above-mentioned U.S. Pat. No. 
3,105,395, to minimize the axial and transverse dimensions of a twin 
countershaft type compound transmission, the mainshaft section 
countershafts, 24 and 26, are displaced about 90.degree. from the 
auxiliary section countershafts. Main section countershafts are supported 
in housing 16 by bearings 90 and 92 while auxiliary section countershafts, 
78 and 80, are supported in housing 16 by bearings 94 and 96. 
Two auxiliary section mainshaft gears, 108 and 110, encircle the mainshaft 
28 and are constantly meshed with and floatingly supported by the 
auxiliary countershaft gear pairs 84 and 86, respectively. Output gear 112 
is splined to output shaft 74 for axial movement relative thereto and 
rotational movement therewith. Output gear 112 is constantly meshed with 
auxiliary countershaft gear pair 88. 
Resiliently biased clutch members 116, 118 and 120 are splined to mainshaft 
28 and, in combination with blockers (shown in FIG. 2) 124, 126 and 128, 
respectively, provide resilient, blocked clutching apparatus of the type 
described in above mentioned U.S. Pat. Nos. 3,799,002, 3,921,469 and 
3,924,484 for selectively clutching gears 108, 110 and 112, respectively, 
one at a time, to mainshaft 28. Clutch 116 is biased axially by spring 130 
and limited in its axial movement by positive stop 134. Clutch members 118 
and 120 are biased axially apart by spring 136 surrounding the mainshaft 
and limited in axial movement by stops 138 and 140. 
Gear 112 is axially moved by shift fork 142 which is movable by shift 
cylinder assembly 144. Mainshaft gears 108 and 110 are joined for joint 
axial movement and independent rotation by ring 146 and are axially 
movable by shift fork 148 movable by shift cylinder assembly 150. Shift 
cylinder assemblies 144 and 150 define a remote servo mechanism 152 by 
which gears 108, 110 or 112 are selectively engaged, one at a time, to 
mainshaft 28. Of course, engagement of gear 112 to the mainshaft 28 is 
effective to couple mainshaft 28 direclty to the output shaft 74. 
Control of servo mechanism 152 is preferably, by a master control means, 
such as selector knob 154 (see FIG. 8) attached to the gear shift lever 
72. typically, master control selector knob 154 will include a movable 
member, such as button 156, or toggle lever, having three unique positions 
("1", "2" and "3") by which one of the auxiliary section power paths, or 
speeds, may be selected. Typically, the auxiliary section master control 
154, and the servo mechanism 152, is fluid and/or electrically operated 
and suitable master-slave valving and/or circuitry is provided. 
The details of the blocked, resiliently biased clutch-blocker assembly of 
the present invention may be seen by reference to FIGS. 4-7. 
The yieldable blocked jaw clutch structures are arranged between the 
shiftable mainshaft gears and the auxiliary section and are provided with 
resilient means for urging engagement thereof as set forth in detail in 
the above mentioned U.S. Pat. No. 3,799,002; 3,924,484 and 3,983,979. 
While clutch means utilizing relatively nondeformable blockers of the 
prior art are not identical with each other, they are generally similar 
and hence insofar as the present invention is concerned, it will be 
sufficient to desribed only one of them in detail with the understanding 
that same may be applied to the other clutch units without difficulty by 
anyone skilled in the art. Therefore, for this purpose, referring to the 
positive jaw clutch unit positioned between the mainshaft gear 108 and the 
mainshaft 28 in the auxiliary transmission seciton 14, said jaw clutch 
unit is generally designated 156 and includes an annular clutch collar or 
clutch member 116 encircling the mainshaft 28. Other means for mounting 
clutch collar 116 to mainshaft 28 allowing relative axial but not 
rotational motion therebetween may be utilized. The clutch collar 116 is 
provided with internal splines 158 which are disposed within corresponding 
external splines 160 provided on the mainshaft 28 for interconnecting the 
clutch collar 116 to the mainshaft 28 for rotation therebetween. However, 
the cooperating splines 158 and 160 permit the clutch collar 116 to freely 
slide axially relative to the shaft 28. A stop ring 134 is seated within a 
suitable groove formed on the external periphery of the shaft 28 and is 
disposed for contacting the clutch collar 116 and limiting the rightward 
axial movement thereof. The collar 116 is normally resiliently urged by 
means of a spring 130 into a butting engagement with the stop ring 134. 
The clutch collar 116 is provided with external teeth 162 thereon which are 
adapted to meshingly engage the internal teeth 164 provided on the 
mainshaft gear 108. The internal teeth 164 form the other jaw clutch 
member of clutch assembly 156. The teeth 162 on the clutch collar 116 are 
tapered, as at 166 and in a similar manner the leading edge of the teeth 
164 on the mainshaft gear 108 are similarly tapered at 168. The tapered 
conical surfaces each extend at an angle of preferably between 30.degree. 
and 40.degree. relative to the longitudinal axis of the mainshaft 28. The 
exact degree of taper, and the advantages, thereof, are explained in 
detail in U.S. Pat. No. 3,265,173. The other end of the spring 130 
resiliently acts against a spring seat member 169 fixed to mainshaft 28. 
A selected number, here three, of the teeth 162 are partially removed for 
permitting the presence of a blocking ring as hereinafter further 
described. Such partial removal leaves, however, an axially shortened or 
partially removed tooth 170 for cooperation with the blocking ring. 
Referring now to the relatively nondeformable blockers; also called blocker 
rings, blocking rings and sensors; which are illustrated in FIGS. 6 and 7, 
one thereof is indicated generally at 124, and comprises a ring encircling 
the clutch member 116 and has an appropriate number, here three pairs, of 
radially inward projections 172 and 174, which when properly positioned 
will mate with the external teeth above mentioned. The inward projections 
or teeth 172 and 174 are contoured at their sides to lie snugly against 
the adjacent ones of the teeth 162, are positioned to project into the 
spaces between a partially removed tooth 170 and the teeth 162 on each 
side thereof. Each pair of projections 172 and 174 are circumferentially 
of less dimension than the corresponding circumferential spaces defined by 
partially removing teeth 170 and thus blocker ring 124 may be rotated in 
either a limited clockwise or counterclockwise direction relative to 
clutch member 116 from the position seen in FIG. 5 in which the space 
between teeth 172 and 174 aligns with partially removed tooth 170. Contact 
of either blocker tooth 172 or 174 by a clutch tooth 162 will limit such 
relative rotation and cause blocker 124 to rotate with clutch member 116. 
The space between the inwardly projecting teeth 172 and 174 is, however, 
of a clearance distance wider than the corresponding circumferential 
dimension of the tooth 170 so that when properly aligned at synchronism 
(or more accurately, when the relative speeds of the clutch components 
cross synchronism) the teeth 172 and 174 will straddle the tooth 170 and 
the clutch member 116 can move axially through but not past blocker ring 
124 to effect engagement with its corresponding gear. 
As may be seen by reference to FIGS. 6 & 7, the end faces of the blocker 
teeth 172 and 172 are tapered as at 176 and 178. The end face of partially 
removed tooth 70 is also preferably provided with tapers to ramps 180 and 
182 complementary with the tapers or ramps 176 and 178 on the blocker ring 
blocking teeth 172 and 174. The angles 183 of the ramps 176, 178, 180 and 
182 is selected such that the blocking teeth and the partially removed 
teeth will remain in proper blocked position when the main transmission 
section 12 is engaged but will tend, under a contacting force, such as 
spring 130 and/or actuator 150, if an auxiliary section shift has been 
selected, to cause the blocker and clutch to assume a nonblocking position 
(by causing relative rotational movement of the clutch 116, blocker 124 
and/or mainshaft 28) if the main transmission section is disengaged, i.e. 
in neutral. A ramp angle 183 of about 15.degree.-25.degree., preferably 
about 20.degree., relative to a plane P normal to the axis of rotation of 
the mainshaft 28 has proven highly satisfactory for most known 
semi-blocked transmission structures. 
As is described in greater detail by reference to above mentioned U.S. Pat. 
Nos. 3,921,469 and 3,924,484, the radially inner side of ring 124 may be 
provided with an inwardly directed groove 184 which receives an annual 
resilient ring 186 which is normally of slightly less internal diameter 
than the external diameter of the teeth 162 so that when the parts are in 
the assembled condition, ring 186 is distorted slightly outwardly thereby 
to exert a light but definite pressure against the external surface of 
said teeth 162. Inasmuch as the ring 186 fits loosely and only in light 
frictional contact with the walls of the groove 184, this effects a 
significant resistance to axial movement between the blocker ring 124 and 
the clutch ring 116 but only an insignificant resistance to relative 
rotative movement therebetween. 
A suitable conical surface 188 projects radially outwardly from the blocker 
ring 124 and is positioned for engagement with a similar conical surface 
190 on a radially inner wall of the gear 108. The axial drag above 
mentioned is sufficient that the rotative driving effect of the surface 
190 onto the blocker 124 is much greater than whatever rotative resistance 
may exist between the blocker 124 and the clutch member 116. Surfaces 188 
and 190 thus provide the blocking torque for the blocked jaw clutch 
assembly. A stop ring 192 limits movement of the blocker 124 away from the 
conical surface 190 when the clutch ring 116 moves out of engagement 
(leftwardly in FIG. 4). 
Referring to FIGS. 5-7, assuming that shaft 28, clutch member 116 and gear 
108 are normally driven in the clockwise direction, it is apparent that 
the nonsynchronous condition comprising gear 108 rotating faster than 
shaft 28 and clutch 116 is sensed by engagement of tooth 170 with 
projection 174 while the opposite condition is sensed by engagement of 
tooth 170 with projection 172. Accordingly, projection 174 may be 
considered the overspeed or upshift projection while projection 172 may be 
considered the underspeed or downshift projection of the projection pair 
172-174. 
The improved blocked jaw clutch assembly of the present invention may 
include a positive means to limit axial movement of clutch member 116 away 
from stop member 134. In FIG. 4, the additional stop means illustrated is 
ring 200. Other means to limit axial movement of the clutch members 116, 
118 or 120 may, of course, be utilized. The stop means is positioned such 
that, when the blocking arrays 170, 172 and 174 are in the blocking or 
non-aligned position, axial movement of clutch 116, and gear 108 which is 
axially fixed thereto under such conditions, will be limited or stopped at 
less than the full leftwardly displaced position of the actuator 150. 
The operation and special advantages of the blocked clutched assembly of 
the present invention may be seen by reference to FIGS. 9A - 9C which 
illustrate the structure and operational function thereof. 
Briefly, FIG. 9A illustrates the neutral position, FIG. 9B illustrates the 
preselect position and FIG. 9C illustrates the gear engaged position, of 
clutch assembly 156. 
Gear 108 is axially moved leftwardly against the bias of spring 130 by 
shift fork 148 and actuator 150. If engagement of gear 108 to mainshaft 28 
is desired, gear 108 will be moved axially leftwardly to the position 
illustrated in FIG. 9B the preselect position. 
In the preselect position, the blocking action of array members 107, 172 
and 174, with blocker 124 in its blocking rotational position relative to 
clutch member 116, will maintain clutch teeth 162 of the clutch member 116 
axially separated from clutch teeth 164 in gear 108. As the blocker 124, 
which tends to rotate with gear 108, is rotated relative to clutch 116 to 
bring the arrays into alignment by causing gear 108 and shaft 28 to cross 
through synchroneous, the jaw clutch will become unblocked and, under the 
bias of compressed spring 130, fire into engagement with gear 108 as 
illustrated in FIG. 9C. 
In the preselect position, as illustrated in FIG. 9B, it is important that 
the blocker 124 remain clocked in the blocking position relative to jaw 
clutch 116 and only rotate relative to clutch 116 to the aligned unblocked 
position as a result of the gear and clutch passing through synchronous. 
Under conditions of low mainshift inertia, i.e. mainsection 12 not 
engaged, the friction surfaces 188 and 190 will first cause the shaft 28 
to rotate substantially synchronously with gear 108, and then the sensor 
unblocking ramps 176, 178, 180 and 182 will cause the blocker 124 to 
rotate relative to the clutch 116 to a nonblocking position. The 
positioning function of the ramps is necessary as a crossing through 
synchronous, not merely achieving synchronous, is necessary to clock the 
blocker from a blocking to a non-blocking position. 
To assure that the action of the sensor unblocking ramps does not 
improperly act on the sensor, the sensor must be subject to blocking 
torque, i.e. the sensor 124 and second jaw clutch member (108 and 164) 
must be properly frictional engaged, at the blocking torque cones friction 
surfaces 188 and 190, to assure the blocker is frictionally urged to tend 
to rotate with the second jaw clutch member. If this frictional contact is 
not properly established and maintained, the sensor unblocking ramps may 
improperly cause the sensor 124 to rotate to an unblocked position 
relative to clutch member 116. 
Referring to FIG. 10, a blocked jaw clutch assembly 210 of the type 
utilizing sensor unblocking ramps is illustrated. Jaw clutch assembly 210, 
except for a structural modification described below, is substantially 
structurally and functionally identical to the blocked jaw clutch assembly 
156. Elements of assembly 210, and of the other alternate embodiments 
described herein having the same or substantially the same structure and 
function as elements of assembly 156 described above will be assigned like 
reference numerals. Assembly 210 includes a blocker or sensor ring 124 
from which a plurality of sets or pairs of blocking teeth or projections 
extend radially inwardly. The three sets, 172 and 174, 172A and 174A, and 
172B and 174B of ramped blocking teeth are spaced substantially 
circumferentially equally about the rotational axis 212 of blocker ring 
124. An equal number of partially removed blocking teeth 170, 170A and 
170B would, in the prior art, extend radially outwardly from jaw clutch 
member 116 for blocking interaction with the blocking teeth carried by the 
blocker 124 to define three substantially equally circumferentially spaced 
arrays of blocking projections, 214, 214A and 214B. 
It has been discovered that the prior art blocked jaw clutch assemblies 
having sensor unblocking ramps thereon have a tendency, under certain 
unfavorable conditions, to improperly become unblocked. It has also been 
found, under experimentation, that this tendency can be minimized and/or 
eliminated by modifying the prior art structure to the structure 210 
illustrated in FIG. 10 such that, upon initial contact of the arrays, the 
blocker 124 is caused to tilt and/or radially shift relative to friction 
cone 190 carried by gear 108, or at least non-symmetrical frictional 
contact between the friction cones 188 and 190 of the blocker member 124 
and gear 108, respectively, is caused. Such tilting and/or radial shifting 
of the blocker and/or non-symmetrical frictional engagement between the 
cone surfaces is believed to minimize or eliminate undesirable unblocking 
because the non-symmetrical contact of the blocking torque friction 
surfaces and/or relative tilting of the members results in an initial 
breakdown of the oil film between the blocking torque friction surfaces 
and thus allows an early establishment of blocking torque on the blocker 
124. Also, a relatively small friction force in the radial direction 
between the members may act in opposition to any premature unblocking 
force generated by the unblocking ramps. In any event, it is believed that 
the present invention provides the observed advantages by assuring that 
the blocking torque caused by the frictional engagement of the cone 
friction surfaces 188 and 190, which cause the blocker to tend to rotate 
with the first clutch member 164, is established and maintained at all 
times that the sensor unblocking ramps are in axial contact. 
The advantages of the present invention may be achieved by a multitude of 
structural modifications, several of which are illustrated in the Figures 
and discussed below by way of example only. 
Referring to FIG. 10, it may be seen, as illustrated in the dotted lines, 
that by removal of the normally present blocking tooth 170A extending from 
the clutch member 116 and/or removal of the blocker teeth or projection 
pair 172A and 174A extending from the blocker 124, a blocked jaw clutch 
assembly will be provided wherein, upon contact of the remaining arrays, 
namely 214 and 214B, the resulting forces will tend to create a tilting 
action on blocker 124 and the friction cone surface 188 carried thereby as 
well as a non-symmetrical frictional contact between the cone friction 
surfaces 188 and 190. Of course, any arrangement of arrays that results in 
a circumferentially nonsymmetrical engagement of said arrays about the 
rotational axis 212 will have a similar advantageous effect. 
FIG. 11 illustrates an alternate embodiment of the present invention 
wherein the groove 220 in which the preenergizing ring 186 is received is 
inclined rather than normal to the rotational axis 212 and thus the 
preenergizer ring 186 will tend to apply a tilt to sensor 124 and friction 
surface 188 carried thereby relative to the rotational axis 212 and cone 
friction surface 190 of gear 108. 
Referring to FIG. 12, a modified pre-energizing ring 216 having a 
non-symmetrical radially inwardly extending portion 218 is illustrated. 
Briefly, pre-energizing ring 216 will be received in pre-energizer groove 
184 in sensor 124 in place of prior art pre-energizing ring 186. The 
action of the nonsymmetrical radially inwardly extending portion 218 on 
the outer radial periphery of the teeth 162 of jaw clutch member 116 will 
cause the blocker 124 to be tilted relative to the axis of gear 108 and 
cone friction surface 190 carried thereby and/or will result in a 
nonsymmetrical circumferential engagement force between the cone friction 
surfaces 188 and 190. 
In FIG. 13 an alternate embodiment of the present invention utilizing a 
modified sensor ring 222 is illustrated. As may be seen, tooth 172, the 
downshift sensing tooth of array 214 is removed as is tooth 174A, the 
upshift sensing tooth of array 214A. Accordingly, during a downshift the 
arrays 214A and 214B will be effective while during an upshift arrays 214 
and 214B will be effective. This provides the advantage of more evenly 
distributing any operating wear than would be the case if one of the 
arrays 214, 214A or 214B, were eliminated for both the upshift and 
downshift sensing directions of relative rotation. 
In FIG. 14, an alternate embodiment similar to that illustrated in FIG. 13 
is illustrated utilizing a modified blocker 230. In blocker 230, the 
leading ramped surface 178 of upshift sensing blocker tooth or projection 
174 of array 214 is cut back i.e. extends less axially rightwardly than do 
teeth 174A and 174B while the leading ramp surface 176A of upshift sensing 
blocker tooth 172A of array 214A is cut back. The ramp surfaces 176B and 
178B, of blocking teeth 172B and 174B, respectively, of array 214B are not 
modified. Preferably, the cut back ramp surfaces are cut back by about ten 
thousandths (10/1000) of an inch thereby assuring a tilting of the blocker 
member 230 and/or non-symetric circumferential engagement between the cone 
clutch surfaces at initial engagement of the arrays. 
As may be seen from the above, improved blocked jaw clutch assemblies with 
sensor unblocking ramps according to the present invention may be provided 
by a multitude of structural modification to the existing prior art 
devices as described and claimed in above mentioned U.S. Pat. Nos. 
3,983,797 and 3,924,484. Accordingly, by relatively simple modification of 
the prior art devices, improved blocked jaw clutch assemblies having 
sensor unblocking ramps, and blocked or semi-blocked transmissions 
utilizing same, are provided. 
Although this invention has been described in its preferred form with a 
certain degree of particularity, it is understood that present disclosure 
of the preferred form is for descriptive purposes only and that various 
modifications and changes in the detailed construction and arrangement of 
the parts may be resorted to without departing from the spirit and the 
scope of the invention as claimed.