Fail-safe locking device for reel carrying systems

A fail-safe locking device for reel support systems is described which is suitable for use with reels such as those used with wire stranders and similar machines. In the embodiments described, a pintle supporting shaft member is normally biased by a spring to an extended position. A safety plunger is provided which has a stepped exterior surface so as to define a recess or step. The safety plunger is normally biased by a spring to a disabling position to urge a blocking member, such as a hardened steel ball or sphere, into the path of movement of an abutment surface of the shaft member to automatically and positively lock the shaft member and the pintle. In the locked condition, the plunger member and, therefore, the pintle, cannot accidentally release the reel. The shaft member and the safety plunger are provided with bearing surfaces against which a fluid medium under pressure may be applied by an operator of the machine to, firstly, move the safety plunger from the disabling to an enabling position to permit the ball or sphere to drop into the recess or notch and, therefore, out of the path of movement of the shaft member abutment surface. Once freed, the plunger member is urged by the fluid medium under pressure to a retracted or releasing position. Two opposing pintle assemblies may be mounted on a cradle typically used in wire stranders, and pneumatic pressure is used by the operator to release the fail-safe locking system to accept or release a reel from the cradle. Electrical means may be used for monitoring the position of the safety plunger and for disabling the machine or issuing an alarm upon movement of the safety plunger to its enabling position and, thereby, permitting the plunger member and pintle to move to a retracted position. The fail-safe locking device is also shown on other reel-supporting systems such as bobbin supporting shafts.

BACKGROUND OF THE INVENTION 
The present invention generally relates to locking mechanisms, and more 
particularly to a fail-safe locking device for reel carrying systems. 
Frequently, machines of various types receive or operate on a workpiece. In 
such machines, it is normally imperative that the workpiece be securely 
maintained in a desired position, both for purposes for safety as well as 
efficient operation. One particular case in point involves wire stranders 
which manufacture stranded cable from a plurality of wires. In one type of 
wire stander, knwon as a tubular strander, the bobbins are placed in 
cradles which are mounted on bearings in a tubular rotatable frame or 
housing. During operation, the frame rotates while the cradle, and the 
bobbins or reels are stationary. The wires are paid-out or pulled from the 
bobbins and are brought along the frame through guides until they are 
wound on the core wire which is usually taken from a bobbin mounted 
outside the frame and passed through the frame along a path that is 
parallel to the axis of the machine, but displaced from the center as are 
the other wires paid-out from the bobbins loaded on the cradles inside the 
tubular frame. Such tubular stranders, as well as rigid stranders and 
planetary stranders are shown and described in the product catalog issued 
by Ceeco Machine Manufacturing Ltd. of Ontario, Canada. 
Since stranders are usually operating at high speeds, and in view of the 
large rotating masses, a large amount of kinetic energy comes into play. 
The safety hazards involved in operating such machines are considerable. 
For this reason, safety devices have been developed which normally do not 
allow the operator to start the machines if any malfunction exists. 
However, due to failures in the safety systems, as well as due to the 
pressures of production, there have been numerous instances of accidents 
which have caused considerable injury to personnel and damage to property. 
A major problem with prior art safety devices is that they normally require 
an operator to perform a number of steps which are time-consuming and, 
therefore, such systems are inconvenient and reduce production. As a 
result of this, cases are known where operators have intentionally failed 
to take the necessary or precautionary steps which ensure the safety of 
operation of the machine. Accordingly, operators cannot always be depended 
upon to carry out the loading operation as prescribed for a safe running 
of the machine, especially when such safety procedures reduce the output 
of the machines, and, therefore, may limit the incentive compensation of 
the operator. Instances are even known where electrical and mechanical 
safety systems have been overridden or intentionally bypassed by operators 
when such systems prevented the operation of a seemingly sound machine. 
The safety problem is particularly severe in the case of a tubular strander 
since the speeds and the energies involved are very high. With respect to 
such tubular stranders, for example, there are basically three 
possibilities or types of accidents which can take place. In the first 
case, the bobbins or reels are not locked properly into position and are 
released during operation. This jams the reels between the rotatable frame 
and the cradle causing the cradle to rotate. The reels are eventually 
thrown out of the tubular frame through the opening thereof. Depending 
upon the direction of exit, the damage can vary. If the reel is ejected 
upwardly, it can penetrate through the roof of the building causing injury 
to persons or damage to property. On the other hand, it can be ejected 
sideways, thus increasing the changes or injuries to personnel as well as 
damage to adjacent machines that can, in turn, trigger further accidents. 
If the bobbin is ejected downwardly, it usually jams the tubular frame 
against the floor and shatters the tube. Accidents of this type are 
frequent and heavy damage to property and people have been recorded. 
A second type of accident involving tubular stranders can be triggered by a 
bearing failure which causes the cradle to rotate together with the frame. 
The consequences of such failure are usually the same since cradles and 
locking mechanisms are currently designed for stationary conditions and 
cannot withstand the forces generated when the cradle and the bobbin are 
rotating at approximately the same speed as that of the tubular frame. The 
consequence of this situation is a release of the reel and a type of 
accident similar to that described above. The third type of accident which 
is possible is that wire gets tangled up around the cradle causing the 
cradle to rotate and resulting in an accident as above described. 
Accidents caused by accidental release of reels have also been recorded in 
the operation of rigid stranders and planetary stranders, but due to the 
lower operational speeds, such occurrences are less frequent. Furthermore, 
the open construction of these machines gives the operator a better 
opportunity to see if a dangerous situation is developing. 
Similar problems such as those discussed in connection with above stranders 
can take place in other types of machinery, particularly where rotatable 
parts or devices are intended to be temporarily and securely retained on a 
machine. For example, on those rigid stranders where reels are mounted on 
cantilevered shafts, operator dependent locking devices are presently used 
for securing the reels on the shafts. Accidents have been recorded where 
reel have separated from the shafts on which they are mounted as a result 
of operator failure to properly secure the manual locking devices. 
Frequently, when the parts are held, such as by pintles, the positional 
instability of the pintles is at least partly caused by the high speeds of 
rotation and the centrifugal forces which are generated thereby. 
Accordingly, such pintles must not deviate from their retaining positions 
irrespective of operator negligence and substantially independently of 
mechanical or electrical failure. Although ball locking devices have been 
used before, for example, on rewinding machines manufactured by Ceeco 
machinery Manufacturing, Ltd., and pneumatic operated spring pintle 
assemblies are used on tubular stranders manufactured, for example, by the 
Stolberger Maschinenfabrik & Co. KG of Aachen, West Germany, there is not 
presently known a fail-safe device for reel carrying systems. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a 
fail-safe locking device for reel carrying systems, which overcomes the 
above-described disadvantages of presently existing reel carrying systems. 
It is another object of the present invention to provide a fail-safe 
locking device which is simple in construction and economical to 
manufacture. 
It is still another object of the present invention to provide a fail-safe 
locking device that considerably reduces the safety hazards caused by 
operator negligence or result from electrical or mechanical malfunction. 
It is yet another object of the present invention to provide a fail-safe 
locking device which is suitable for use with pintle assemblies mounted on 
cradles or other shaftless reel carrying systems used in wire stranders. 
It is another object of the present invention to provide a fail-safe 
locking device suitable for use with shaft-mounted bobbins or reels, 
particularly cantilevered shafts on rigid-type stranders. 
It is a further object of the present invention to provide a fail-safe 
locking device which utilizes a primary, spring actuated locking element, 
and also includes a secondary mechanical lock which automatically blocks 
the mechanical movement of the primary element to allow the system to 
withstand large centrifugal forces. 
It is still a further object of the present invention to provide a 
fail-safe locking device which utilizes hydaulic pressure, such as 
pneumatic means, for moving a secondary mechanical locking mechanism to a 
position which permits a primary locking mechanism on which a reel 
engaging assembly is mounted to move from a retaining position to a 
releasing position. 
It is yet a further object of the present invention to provide a pneumatic 
actuated fail-safe locking device for reel engaging assemblies wherein 
primary and secondary locking devices can only move to releasing positions 
upon application of pneumatic pressure, and the primary and secondary 
locking devices are spring actuated to automatically return to their 
locking or retaining positions as soon as the pneumatic pressure is 
removed. 
It is an additional object of the present invention to provide a fail-safe 
locking device which requires positive action by an operator to release a 
reel or bobbin retained by a reel engaging assembly, but which 
automatically and without any positive steps taken by the operator reverts 
and positively locks the reel engaging assembly in its retaining position. 
It is an additional object of the present invention for providing a primary 
locking reel engaging mechanism, and a secondary mechanical lock for 
preventing any movements of the primary reel locking mechanism prior to 
application of a pneumatic pressure to the secondary mechanical lock, and 
further including electrical monitoring means for monitoring the position 
of the secondary mechanical lock to disable the associated machine upon 
movement of the secondary mechanical lock from its locking or disabling 
position to its releasing or enabling position. 
It is yet an additional object of the present invention to provide a 
fail-safe locking device which includes a primary locking element or 
member on which the reel engaging mechanism is mounted, a secondary 
mechanical lock which normally locks the position of the primary locking 
element and prevents movement thereof, and which includes means to apply a 
pneumatic pressure to the primary locking element and the secondary 
mechanical lock to release the secondary mechanical lock and move the 
primary locking element to its retracted or releasing position. 
In order to achieve the above objects, as well as others which will become 
apparent hereafter, the fail-safe locking device for a reel carrying 
system which is mounted on a support member in accordance with one 
embodiment of the present invention comprises a first actuatable member 
mounted for slidable movement relative to the support member along an axis 
between first and second positions. Engaging means cooperate with said 
first actuatable member for securely engaging a reel on the reel carrying 
system in said first position of said first actuatable member and for 
releasing the reel in said second position of said first actutatable 
member. First biasing means is provided for urging said first actuatable 
member to said first position. Locking means is provided which cooperates 
with said first actuatable member and the support member and is movable 
between locking and releasing positions for permitting movement of said 
first actuatable member from said first to said second positions only in 
the releasing positions thereof. A second actuatable member is provided 
mounted for slidable movement relative to the support member between the 
enabling and disabling positions for moving said locking means from said 
locking to said releasing positions only in the enabling position thereof. 
Second biasing means is provided for urging said second actuatable member 
to said disabling position, said first and second actuatable means being 
provided with bearing surfaces. Hydraulic means is provided which is 
adapted to apply a fluid medium under pressure to said bearing surfaces 
for moving said actuatable member to said enabling position only upon 
application of said fluid medium under pressure to thereby permit movement 
of said locking means to said releasing position, and for subsequent 
movement of said first actuatable member and said pintle to said pintle to 
said retracted position. 
In one presently preferred embodiment, the first actuatable member is a 
spring activated mechanism or element which is coupled with a secondary 
mechanical locking system which comprises the second actuatable member, 
the secondary mechanical locking system automatically and positively 
locking the spring activated mechanism until an operator applies hydraulic 
or pneumatic pressure to the coupled members. The primary locking action 
by said engaging means is advantageously caused by a spring, but once the 
secondary mechanical locking system has operated, it mechanically locks 
the movement of said engaging means, thus allowing the system to withstand 
the large centrifugal forces generated during an accident. 
The system is not operated manually, but can be opened only by using 
hydraulic means, such as air pressure which could be applied, for example, 
through a coupling on a reel-supporting cradle which supports the 
fail-safe locking system. The operator uses an air pressure flexible hose 
which is provided on the stationary supports of the tubular rotating 
frame. To open the locking device, the operator places the nozzle of the 
air pressure hose on a coupling positioned on the cradle. The air pressure 
causes the secondary lock to release and then forces the primary locking 
to move against the springs freeing the empty reel for unloading. Once the 
new loaded reel is positioned in the cradle, the operator disconnects the 
air hose, the spring-loaded mechanism locks the reel and automatically 
moves the secondary lock to a position which positively locks the primary 
locking element and the engaging means supported thereon. 
Therefore, the locking devices operates irrespective of operator action. If 
by chance the operator forgets to remove the air pressure hose, an 
electrical interlock on the secondary locking device may be provided which 
prevents the machine from rotating. However, if by a system failure the 
machine rotates during its first revolution, it will sever the pressure 
hose, thus eliminating air pressure from the self-locking device. Under 
this condition, the mechanism will self-lock and avoid accidental release 
of the reel. 
Accordingly, the apparatus in accordance with the present invention 
provides a fail-safe locking device which automatically reverts to its 
locking mode independently of operator negligence or inaction, and 
prevents an operator from bypassing the system by positive action or 
inaction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will be primarily described, by way of illustration 
only, with respect to pintle assemblies on tubular-type stranders. 
However, as will become evident to those skilled in the art, and as will 
be briefly described in connection with FIGS. 10 to 15, the locking device 
of the present invention can also be used with other reel-engaging means 
on other reel carrying systems. 
Referring now specifically to the drawings, in which the identical or 
similar parts have been designated by the same reference numerals 
throughout, and first referring to FIGS. 1-3, the locking device of the 
present invention is generally designated by the reference numeral 10. As 
will become evident from the description that follows, and as noted above, 
while the fail-safe locking system of the present invention is described 
as being incorporated in pintle assemblies mounted on cradles and the like 
as used on wire stranding machines, the same or similar fail-safe locking 
systems can be used in many other types of applications where a movable or 
retaining member is intended to normally be positioned in an extended or 
retracted position and only moved to a retracted or extended position 
respectively when the associated machine is not in operation. 
As can best be seen in FIGS. 2 and 3, two pintle assemblies 10 are 
provided, although it should be clear that in certain instances only a 
single locking device or pintle assembly 10 in accordance with the present 
invention may be sufficient, in which case the other pintle is fixedly 
mounted on the frame. The pintle assemblies 10 are shown to be provided at 
the free ends facing inwardly or facing each other with pintles 12. The 
pintle assemblies 10 are mounted on a cradle frame 14. The cradle 14 is 
typically of the type used in high speed tubular stranders manufactured by 
Ceeco Machinery Manufacturing Ltd. The tube 16 of such tubular stranders 
are shown in dashed outline in FIGS. 2 and 3. Such cradles 14 are 
typically provided with a quick rekease brake mechanism 18 which 
cooperates with a brake ring 20 in a known or conventional manner. A drive 
dog 22, also of a conventional type, is provided on the brake ring 20. A 
conventional reel stop 24 is shown which is adapted to cooperate with the 
reel 26 when the same is received within the cradle 14 and supported by 
the pintles 12. In FIG. 1, the reel 26 is shown to be filled with wire 28 
which is to be stranded, which reel includes a bore 30 dimensioned to 
receive the pintles 12 therein. The reel 26 is shown being lowered by a 
hoist 32 into position within the cradle 14. As will be described 
hereafter, the pintles 12 are, during such an operation, in the retracted 
positions thereof to permit the reel 26 to be lowered into the cradle 14, 
after which the pintles 12 are moved to their extended positions, as 
suggested in FIGS. 2 and 3 in which condition the reel 26 is securely 
retained. The pintle assemblies 10 of the precent invention assure that 
the pintles 12 remain in their extended positions during the operation of 
the machine to retain the reels 26 securely and prevent the same from 
inadvertently or accidentally be ejected from the cradle 14. 
Referring to FIG. 4, there is shown the details of the pintle assembly 10 
in accordance with one presently preferred embodiment of the present 
invention which forms the fail-safe locking system which assures that the 
pintles 12 are locked in the extended positions thereof, this taking place 
automatically without the need for the operator to take precautionary 
steps as has heretofore been required. Additionally, the pintle assembly 
10 of the present invention permits and causes retraction of the pintles 
12 only upon application of a hydraulic fluid under pressure, such as 
pneumatic pressure, as will be described hereafter. 
The cradle 14 includes a frame which may, for example, include an inwardly 
directed annular flange 34 to which a cylinder 36 and an end plate 38 are 
securely attached by means of bolts 40. The end plate 38 includes an 
inwardly directed cylindrical wall portion 42 which defines an axial bore 
or cylindrical cavity and which is provided with one or more through 
openings 44, as is best shown in FIG. 5 and will be more fully described 
hereafter. 
As can best be seen from FIG. 4, the cylinder 36 includes a stepped-down 
cylndrical wall 37 which defines a cylindrical cavity or bore 37' which 
receives a portion of a first actuatable member or primary locking element 
46 which is mounted for slidable movement within the cylinder 36 relative 
to the support member or cradle 14 along an axis. The primary locking 
element 46 is in the nature of a shaft member and includes a shaft portion 
48 dimensioned to correspond with the interior bore or cavity defined by 
the cylinder 36. The primary locking element 46 is provided at one end 
thereof with a piston portion 50 which will be more fully described 
hereafter. 
The primary locking element 46 is provided at the end opposite to where the 
piston portion 50 is provided with a front plate 52 which is secured to 
the shaft portion 48 by means of bolts 54. The front plate 52 secures ball 
bearings 56 against a spring support plate 58 which in turn is urged in 
the direction of the spring support plate by means of a helical 
compression spring 60 which acts between the cradle frame 14 and the 
spring support plate 58. 
Mounted on the ball bearings 56 is the pintle 12 which is clamped to the 
ball bearings by means of a back-up ring 62 which is connected to the 
pintle 12 by means of bolts 64 and spring lock washers 66 as shown. In 
order to protect the spring 60 and keep the interior of the pintle 
assembly 10 free of contaminants, there is advantageously provided a 
spring cover 68 which is connected to the back-up ring 62 and which shares 
the common axial movement of the pintle 12 together with the movements of 
the primary locking element 46. 
With this arrangement, the primary locking element 46, together with the 
pintle 12, are urged outwardly to the extended position thereof as shown 
in FIG. 4 to cause at least a portion of the pintle 12 to be received 
within the bore 30 of the reel 26. 
To limit excessive movements of the primary locking element, the set screw 
72 is positioned within a groove 70 to prevent rotation of the primary 
locking element 46 when the pintle 12 and the reel 26 rotate. Locking of 
the primary locking element against rotation prevents wear, for example, 
of the O-ring 82 and prolongs the life of the locking device 10. The 
primary locking element 46 is limited in its movement beyond its extended 
position by virtue of its piston portion 50 coming into engagement with an 
annular shoulder of the cylinder 36 as shown in FIG. 4. 
The cylinder 36 as well as the end plate 38 are configurated and cooperate 
together to form a bore or cavity 74 which generally contains the piston 
portion 50, and which is defined by a cylindrical surface 76 which 
corresponds to the peripheral configuration of a bearing surface 78 formed 
on the piston portion 50. 
As will be more fully described hereafter, there is provided a conduit 80 
which is in communication with the bore or cavity 74 for selectively 
applying a fluid medium under pressure against the bearing surface 78. To 
ensure efficient operation, there is advantageously provided a seal about 
the periphery of the piston portion 50, shown in FIG. 4 as being an O-ring 
82. 
The primary locking element is provided with an abutment surface 84, shown 
in the embodiment of FIG. 4 as being generally in the region of the piston 
portion 50. The abutment surface 84 is an important feature of the present 
invention and will be more fully described below. The primary locking 
element 46 is also provided with a bore or cavity 86 which is defined by a 
cylindrical surface 88, which bore or cavity 86 is also in fluid flow 
communication with the conduit 80. In this manner, application of a fluid 
medium under pressure into the conduit 80 simultaneously applies the fluid 
under pressure to both cavities 74 and 86. 
Coaxially arranged with the primary locking element 46 is a second 
actuatable member in the nature of a secondary mechanical locking system 
or safety plunger 90 which has a shaft portion 92 provided with a piston 
portion 94 at one end thereof which is similar in configuration and 
functions as the piston portion 50 of the primary locking element 46. The 
piston portion 94 has a bearing surface 96 which faces the interior of the 
bore or cavity 86, and has a periphery which generally corresponds to the 
shape of the cylindrical surface 88. In order to prevent escape of the 
fluid under pressure and generally improve the operation of the device, 
there is advantageously provided a seal extending about the periphery of 
the piston plunger 94, such as in an annular groove 98 (shown in FIG. 5), 
which may be in the nature of an O-ring 100. 
The end of the shaft portion 92 opposite to where the piston portion 94 is 
provided is formed with an axial bore 102 as shown which receives a 
helical compression spring 104 which acts between the safety plunger 90 
and an end plate 106 fixedly mounted relative to the cradle frame 14 to 
thereby urge the safety plunger or secondary mechanical locking plunger 90 
in the direction of the primary locking element 46 to move the piston 
portion 94 inwardly of the bore or cavity 86. 
Referring particularly to FIG. 5, the safety plunger or locking element 90 
is formed with a step or notch 108 in its exterior surface to define a 
generally bevel or inclined surface 110 as shown. An important feature of 
the present invention is that when the safety plunger 90 is in its 
disabling position shown in FIGS. 4 and 5, the greater dimension of the 
shaft portion 92 is substantially in opposition to the through opening 44 
in the wall portion 42. Therefore, the function of the spring 104 is to 
urge the safety plunger 90 to move to the disabling position and bring the 
greater diameter or dimension on the shaft portion of the safety plunger 
substantially in opposition to or in registry with the through opening 44, 
for reasons which will be described below. 
To prevent excessive axial movement of the safety plunger 90 beyond its 
disabling position shown in FIGS. 4 and 5 as a result of the action of the 
spring 104, suitable stop means may be provided. As best shown in FIG. 6, 
one form of stop means which may be used for this purpose may consist of 
one or two pins 112 which are spaced from the axis and directed 
substantially normally thereto. Such pins 112 are mounted on the wall 
portion 42 at a radial distance to substantially correspond to the radial 
distance of the bevel or inclined surface 110 from the axis, so that the 
pins 112 abut against the bevel or inclined surface 110 to thereby limit 
in this manner excessive axial movement of the safety plunger 90. However, 
any other type of stop means may be used in place of the pins 112. 
Referring to FIGS. 4 and 5, an important feature of the present invention 
is the provision of a blocking member in the nature of a hardened steel 
ball or sphere 114 which is captured within the through opening 44 and 
mounted for only radial movements. In FIGS. 4 and 5, the ball 114 is shown 
to be in a radially outward locking position wherein the ball 114 is at 
least partially positioned in the path of movement of the abutment surface 
84 to block movement of the primary locking element 46 from the extended 
position as shown in FIG. 4. In this condition, the ball 114 is maintained 
in the radially outward or blocking position due to the disabling position 
of the safety plunger 90 which forces the ball 114 to the position shown 
as the result of the action of the spring 104. 
The diameter of the ball 114 is selected to be greater than the thickness 
116 of the wall portion 42, so that at least a portion of the ball 114 
projects beyond the wall portion 42 to assure that the primary locking 
element 46 is blocked and prevented from axially moving from its extended 
position. With this arrangement, it should be clear that the ball 114 is 
captured within the through opening 44 and prevented from moving axially 
as the result of the fixed nature of the wall portion 42. However, the 
ball 114 may move radially inwardly or outwardly, and will so move in 
response to radial forces applied thereto. However, although the primary 
locking element 46 may apply radially inward forces to the ball 14, the 
ball cannot move out of the blocking path or path or movement of the 
abutment surface 84 so long as the safety plunger 90 is in its disabling 
position as shown in FIG. 4 and 5. 
Referring to FIG. 5, the increased diameter shaft portion 92, which has a 
substantially cylindrical external surface, is provided with a 
longitudinal surface groove 118 for each hardened steel ball 114. The 
grooves 118 terminate short of the step 108 to form ledges or banks 118' 
which prevent a ball 114 from rolling out of the groove 118 into the step 
108, wherein the primary element 46 applies a radially inward force on the 
ball, such as when centrifugal forces act on the primary element 46. 
As is evidence from FIGS. 4 and 5, the primary locking element 46 cannot 
move because the four balls 114 do not allow it to retract into the 
cylinder 36 as long as the secondary safety plunger 90 is in the extended 
locked position. However, if pressure is applied to the pintle, this force 
will act on the four balls pushing them radially inwardly toward the 
safety plunger 90. Centrifugal forces will tend to urge the primary 
locking element 46 to apply such inward forces on the balls 114, as well 
as tend to move the secondary safety plunger 90 to its retracted, enabling 
position against the action of the spring 104. The spring 104 can be 
designed in such a way as to maintain the safety plunger in its disabling 
position under the effect of high centrifugal forces, but, even if it is 
such that it could not maintain the safety plunger in its disabling 
position under high centrifugal forces, the ledges or banks 118' prevent 
the safety plunge from moving from its normally extended disabling 
position to its retracted enabling position whenever the primary locking 
element 46 applies radially inward forces on the safety plunger. This is 
due to the engagement between the balls 114 and the ledges 118'. 
Therefore, even under very high pressure, the pintle 12 is mechanically 
and positively locking in position. Even if the cradle 14 rotates at the 
speed of the tubular frame, and considerable axial forces are applied to 
the pintle, it would be impossible to obtain a release up to forces that 
will destruct the entire assembly. During normal operation, the primary 
locking element does not apply radially inward forces on the balls 114 and 
movement of the safety plunger 90 against the action of the spring 104 
merely causes the balls 114 to roll over the ledges or banks 118' and 
subsequently drop into the step 108 as described above. By making the 
ledges or banks 118' typically a few thousandths of an inch high, these 
are small enough to permit the balls to roll over them without any 
difficulty under retracting movements of the safety plunger 90, while 
actually locking the safety plunger whenever the primary locking element 
46 applies radially inward forces on the balls 114. As noted above, even 
small ledges or banks have been found to be satisfactory to prevent 
inadvertent unlocking of the pintle assembly 10 even under the highest 
anticipated centrifugal forces. 
While one blocking member may be provided, it is advantageous to provide a 
plurality of such blocking members which are substantially uniformly 
spaced from each other about the axis of the pintle assembly 10 and, in 
the embodiment shown in FIGS. 1-6, there are four balls 114 spaced from 
each other 90.degree. apart, as best shown in FIG. 6. Each ball 114 is 
received with an associated through opening 44, and the operation of each 
of the balls 114 is substantially the same as described above. Also, while 
a spherical ball bearing is shown in the presently preferred embodiment, 
it will become evident to one skilled in the art that the blocking members 
need not be spherical, but may assume any desired configuration, as long 
as the blocking members at least partially project into the path of 
movement of the abutment surface 84 when the safety plunger 90 is in its 
disabling position. Thus, the blocking members may be in the nature of 
cylinders, pins, plungers and the like. The present invention, therefore, 
is not limited to the specific constructions described, but to the general 
principles which have been described which provide automatic and positive 
locking of the primary locking element 46 by means of the actions of the 
secondary locking element or safety plunger 90 in cooperation with the 
movable blocking element or ball 114 which cooperates with an abutment 
surface of some type on the primary locking element. 
The pintle assembly 10 is advantageously also provided with an electrical 
limit switch 120 which serves as a sensor means for monitoring the 
position of the safety plunger 90. The limit switch 120 has a plunger 122 
which projects into the path of movement of the safety plunger 90, the 
position of the limit switch 120 being maintained by means of a limit 
switch clamping plate 124 which is fixedly mounted on the end plate 38 by 
means of bolts 126. To facilitate actuation of the limit switch 120 and 
prevent damage thereto, the shaft portion 92 of the safety portion 90 is 
advantageously provided with a bevel surface 128 which is in the nature of 
a cam surface which initiates the actuation of the limit switch 120 when 
the safety plunger 90 moves from the disabling position thereof shown in 
FIGS. 4 and 5 to an enabling positon to be described. The limit switch 120 
is provided with electrical conductors or leads 130 which may be connected 
to any suitable electrical circuit which may, for example, disconnect the 
machine on which the pintle assembly 10 is mounted from the power mains or 
may initiate an alarm upon movement of the safety plunger 90 from its 
disabling position which thereby enables the movement of the primary 
locking element 46. 
Referring to FIGS. 2 and 4, the conduit 80 is shown to be in fluid flow 
communication with a nipple 132 which is in turn coupled by means of an 
elbow 134 to a tubing 136 which extends to an accessible portion of the 
cradle 14. The tubing 136 is connected by means of a female branch tee 138 
to a speed coupler and connector 140. As is evident from FIG. 2, the 
female branch tee 138 permits steel tubes to emanate from the coupler 140 
to both pintle assemblies 10 on opposing sides of the cradle frame 14. 
The operation of the pintle assembly 10 will now be described to the extent 
to which it has not been described above. The spring 60 urges the primary 
locking element 46 to its extended position shown in FIG. 4, and the 
safety plunger 90 is urged to its disabling position as a result of the 
action of the spring 104, causing the ball 114 to ride over the surfaces 
110 and ledges 118' and on to that portion of the shaft portion 92 of 
greater diameter to cause at least a portion of the balls 114 to move into 
the path of movement of the abutment surfaces 84. This action of the 
helical compression springs 50 and 104 automatically moves the pintle 12 
to its extended or retaining position without reliance upon the operator 
of the machine. The primary locking element 46 and the safety plunger 90 
will remain in these extended and disabling positions respectively until 
the operator of the machine applies a fluid medium under pressure to the 
coupler 140. 
In order to insert a reel 26 or remove the same from the pintle 14, the 
operator applies a mating coupler to the connector 140, such as an air 
pressure hose, and simultaneously applies pressure through the tubings 136 
to the conduits 80 of each of the pintle assemblies 10. Application of air 
under pressure into the conduit 80 of the pintle assembly 10 shown in FIG. 
4 causes a pressure P to be developed on each of the bearing surfaces 78 
and 96. However, initially the pressure applied to the bearing surface 78 
do not move the primary locking element 46 because it is locked by the 
balls 114 which are in abutment against the surfaces 84 as described 
above. However, the fluid pressure P is shown to be acting upon the 
bearing surface 96 in FIG. 4 to develop a force F1 which acts upon the 
safety plunger 90 and urges the same to move away from its disabling 
position and move to its enabling position against the action of the 
spring 104. Movement of the safety plunger 90 to its enabling position 
shown in FIG. 7 brings the step 108 into registry with the through 
openings 44 to permit the balls 114 to moe sufficiently radially inwardly 
so as to move out of the path of movement of the abutment surfaces 84. 
Thus, movement of the safety plunger 90 in this manner causes the ball 
bearings to move from their locking to their releasing positions. 
Referring to FIG. 7, the fluid under pressure continues to apply pressure P 
upon the bearing surface 78 to thereby apply a force F2 which causes the 
now released primary locking element 46 to move from its extended position 
to its retracted position against the acton of the compression spring 60. 
The above-described construction, therefore, automatically provides 
positive locking of the primary locking element 46 which bears the pintle 
12, while the same external fluid under pressure which releases the 
primary locking element 46 also urges the same to move to its retracted 
position to thereby facilitate insertion and removal of the reels 46 from 
the cradle frame 14. 
As soon as the pneumatic or hydraulic pressure is applied to the conduit 
80, and the safety plunger 90 is moved from its disabling to its enabling 
position, the limit switch 120 is actuated by virtue of engagement between 
the plunger 122 and the can surface 128. This can be used, as suggested 
above, to disable the machine by removing the electrical power therefrom 
whenever the safety plunger 90 is in any position other than the disabling 
position shown in FIG. 4, or may be used to actuate an alarm which 
provides notice to the operator that the pintle 12 is not in its extended 
or retaining position. 
When used in conjunction with cradles 14 on tubular stranding machines, the 
locking device including the ball 114 and the bearing surfaces 84 comes 
into play only when needed since during normal operation the spring 60 is 
sufficient to maintain th pintle 12 in the reel 26. Only when a 
malfunction occurs is the locking device which includes the abutment 
surfaces 84 and the balls 114 subjected to stresses. This construction, 
therefore, increases the life and the reliability of the device because 
under normal circumstances the abutment or engaging surfaces which make up 
the locking device are not subjected to any wear at all. 
In the embodiment 10 shown in FIGS. 1-7, the springs 60 and 104 are 
arranged to urge the primary locking element 46 and the safety plunger 90 
in a common axial direction, the bearing surfaces 78 and 96 facing that 
same axial direction. In this manner, the application of a fluid medium 
under pressure causes the primary locking element 46 and the safety 
plunger 90 to be successively axially shifted or displaced against the 
actions of the two springs respectively. Referring to FIGS. 8 and 9, a 
second embodiment 10' of the pintle assembly is shown which need not rely 
on spring action alone or spring action in combination with ledges 118' to 
maintain the safety plunger 90 in its disabling position under the action 
of centrifugal forces. Here springs 60 and 104' are arranged to urge the 
primary locking element and the safety plunger 90' in opposing axial 
directions This is done to benefit from the effect of the centrifugal 
forces acting on the safety plunger to urge the same to its disabling 
position and thereby add another measure of safety to the locking device 
10'. The bearing surface of each associated actuatable member faces the 
direction of action by the cooperating spring thereon. In FIG. 8, the 
primary locking element 46' is shown in its extended or retaining position 
due to the action of the compression spring 60, this position being 
towards the left as viewed in FIG. 8, similar to the corresponding 
position of the pintle assembly 10 shown in FIG. 4. However, now the 
spring 104' acts between an abutment or shoulder on the wall portion 42' 
and the safety plunger 90' to move the same to the disabling position 
which with the embodiment 10' is towards the right as viewed in FIG. 8, as 
compared with the corresponding position towards the left with the 
embodiment 10 shown in FIG. 4. 
Upon application of a fluid medium under pressure into the conduit 80', 
forces F3 and F4 are simultaneously applied to the bearing surfaces 96' 
and 78' respectively. However, the primary locking element 46' cannot move 
in the direction of force F4 because it is positively locked by virtue of 
the engagement between the ball 114 and the abutment surface 84'. The only 
element which is free to move is the safety plunger 90' which moves 
towards the left, as viewed in FIG. 7, in response to the force F3 
Referring to FIG. 9, once the safety plunger 90' has moved into the bore 
cavity 86 sufficiently so as to bring the step 108 or the inclined surface 
110' sufficiently to the left so as to permit the ball 114 to move out of 
the path of movement of the primary locking element 46', the force F4 
causes the primary locking element 46', together with the pintle 12 
mounted thereon, to move towards the right to the position shown in FIG. 
9. The movements of the safety plunger 90' from the disabling to the 
enabling positions, the ball 114 from the locking to the releasing 
positions, and the movement of the primary locking element 46 from the 
extended or retaining positions to the retracted or releasing positions 
are all automatically achieved upon application of a fluid medium under 
pressure to the conduit 80'. As soon as such pressure is removed, 
compression springs 60 and 104' automatically, and without any assistance 
from the operator, revert to their initial positions shown in FIG. 8 to 
positively lock the pintle 12 in the operative or retaining position. 
In the embodiment 10' shown in FIGS. 8 and 9, the safety plunger is 
maintained in the disabling position by the action of the centrifugal 
forces acting thereon. The centrifugal forces in this embodiment urge the 
safety plunger in the same direction as does the spring 104', as opposed 
to the embodiment 10 where the centrifugal forces oppose the spring 104 
and tend to move the safety plunger to the enabling position. Although 
this alternative embodiment shown in FIGS. 8 and 9 would, therefore, seem 
to provide superior safety, testing has shown that the pintle assembly 10 
adequately and positively maintains the safety plunger 90 in the disabling 
position shown in FIG. 4 even at forces considerably greater than the ones 
that would be encountered in the worst accidental condition as discussed 
above. The pintle assembly 10 is somewhat preferred because of its 
simplicity of construction. As can be seen, the pintle assembly 10' uses a 
considerable number of additional O-rings 82', 142 and 144, and this 
increases the chances of malfunction and maintainance. 
The two above-described embodiments of pintle assemblies 10 and 10' are 
only illustrative of the basic principle of the present invention. 
Numerous modifications of the described constructions may be made while 
still practicing the invention as defined in the appended claims. For 
example, while the bearing surfaces against which the fluid medium under 
pressure is applied have been shown as being disposed or provided on 
piston portions or on annular lips or wall portions of such pistons, the 
fluid medium can be applied to the slidably mounted postions or plungers 
in other conventional manners. Also, while the primary locking elements 
and the safety plungers have been shown to be telescopically arranged in 
the presently preferred embodiments so that application of fluid medium 
under pressure changes the overall effective lengths of the actuatable 
members, this is not, in and of itself, a critical feature of the present 
invention and any other arrangement of the slidably mounted pistons or 
plungers which achieves the functions above described can be used. 
The present invention contemplates other modified constructions which 
automatically, by action of hydraulic or pneumatic pressure, provide 
positive locking action, this irrespective of the specific mechanical 
constructions which have been described above. It is easy to see, for 
example, that the system could be reversed using compressed air to close 
the pintle assembly to move the primary locking element to the extended 
position, while utilizing the action of the compression springs to open it 
or move the primary locking element to the retracted or releasing 
position. However, in such a case, the locking system would be 
continuously under stress since it would have to counteract the force of 
the spring which tends to open the spindle. In this situation, a failure 
of the locking system would cause an accident while in the above described 
arrangements it would not. 
While the fail-safe locking device for reel carrying systems has primarily 
been described above in connection with pintle assemblies of the type 
commonly used on cradles in tubulartype stranders, it should be evident 
from the above description that the fail-safe locking devices may be 
utilized in other reel carrying systems whenever a reel or bobbin is to be 
securely and releasably and positively locked in place. More specifically, 
the reel engaging means cooperating with the primary locking element 46 in 
the embodiments shown in FIGS. 1-9 is in the nature of a pintle mounted on 
the shaft portion 48 of the primary locking element 46. However, numerous 
other applications exist where engaging means other than pintles may be 
mounted on and cooperate with the shaft portions 48 of the locking device 
10. 
To illustrate some other examples or possible applications of the fail-safe 
locking device in accordance with the present invention, reference is made 
to FIGS. 10 and 11. Here, a rigid-type strander 146 is shown to comprise a 
frame generally in the nature of a hollow body 148. A support member in 
the nature of a shaft 150 is shown fixedly or rigidly mounted on the frame 
148, the shaft 150 having an axis substantially normal to the axis of 
rotation of the hollow body 148. Such an arrangement may be utilized to 
pay off wire from the bobbin as a result of centrifugal forces acting on 
the wire as the bobbin or reel 152 rotates about the axis of the hollow 
body 148. The bobbin or reel 152 has a bore 152a dimensioned to receive 
the shaft 150 as shown in FIG. 11. The bobbin or reel 152 has upper and 
lower flanges or circular members 152b, 152c which define the annular 
space in which the wire on the bobbin is wound. 
In stranders of this type, wherein rotation of a shaft or hollow body has 
the tendency to eject the bobbins or reels, it is imperative that suitable 
locking means be provided. As best shown in FIG. 11, the fail-safe locking 
device 10a is shown incorporated within the shaft 150 and fixedly secured 
thereto in any suitable or conventional manner. The shaft portion 48a of 
the actuatable member or primary locking element 46 is shown to be 
provided with a conical or tapered outer surface, tapering inwardly in the 
direction of the reel or bobbin engaging means. Here, in place of a pintle 
12 mounted on the shaft portion, the reel or bobbin engaging means 
includes a plurality of fingers 154 spaced from each other about the axis 
of the shaft 150 and mounted for slidable movement in the radial direction 
on the shaft 150. Suitable compression springs 156 are provided which urge 
the fingers 154 radially inwardly or into the confines of the shaft 150. 
The springs 156 have the tendency of moving the fingers 154 to their reel 
or bobbin disengaging position, which position the fingers 154 move to 
when the shaft portion 48a is in the retracted position as suggested by 
the dashed outline in FIG. 11. As noted above. the primary locking element 
is normally locked in the extended position thereof shown in FIG. 11. As 
should be evident, when the shaft portion 48a moves to its locked, 
extended position shown in FIG. 11, the fingers 154 ride on the tapered 
external surface of the shaft portion as shown, thereby, a thrust 
outwardly to the locking or engaging positions shown. The shaft portion 
48a forces the fingers 154 radially outwardly against the actions of the 
springs 156 to the engaging or locking positions thereof, the fingers 
engage the bobbin or reel 152 at the upper flange or circular member 152b. 
Since the shaft 150 is rigidly or fixedly connected to the rotating frame 
or hollow body 148, the fingers 154 likewise maintain the bobbin or reel 
152 shaft 150 during rotation thereof. From the above-described 
embodiments, application of a pneumatic or hydraulic pressure in the line 
158 causes the shaft portion 48a to move to a retracted, releasing 
position (as shown in dashed outline in FIG. 11) to thereby permit the 
fingers 154 to move radially inwardly by the action of the springs 156 and 
the bobbin or reel 152 may be released. 
Referring to FIGS. 12 and 13, there is shown a still further embodiment of 
reel engaging means which avoids the need to maintain the springs 156' in 
a state of compression during the locked condition of the bobbin, as is 
the case with the embodiment shown in FIGS. 10 and 11. In FIGS. 12 and 13, 
the shaft portion 48b is normally locked in the retracted, as opposed to 
the extended position as shown in FIG. 11. With the shaft portion 48b 
normally being in the retracted position as shown in FIG. 12, the shaft 
portion 48b may be provided with a tapered or conical surface which tapers 
in an opposite direction as the taper of the shaft portion 48a. With the 
embodiment shown in FIGS. 12 and 13, the locking device 10b must be 
slightly modified, as should be evident to those skilled in the art, to 
cause the shaft portion 48b to be in the locked position of the shaft 
portion when it is in a retracted position, shown in FIG. 12. Here, the 
fingers 160 have a generally sloping surface as shown riding upon the 
conical or inclined surface of the shaft portion 48b. When the shaft 
portion 48b is in the retracted position, the compression springs 156' 
urge the fingers 160 to move to their extended or locked positions. It 
will, therefore, be evident that with the shaft portion 48b locked in the 
retracted position and by utilizing the tapered surface of the shaft 
portion 48b, the fingers 160 may be maintained in their extended locking 
positions without placing the springs 156' in a state of compression. 
When the shaft portion 48b is moved to its extended position, as shown in 
FIG. 13, the fingers 160 are caused to ride upon the inclined surface of 
the shaft portion, and are moved radially inwardly to the releasing 
positions thereof. 
In FIGS. 14 and 15, the design of the shaft portion of 48c, as well as the 
fingers or bobbin engaging means 160' is so selected so that the fingers 
160' are in the their extended, locking positions when the primary locking 
element or actuatable member is locked in the extended position as is the 
case in FIG. 11. However, in this embodiment, the springs 156 are not 
placed in a state of compression in the normal, locking positions of the 
fingers 160'. The arrangements shown in FIGS. 10, 11, 14 and 15 utilize 
the fail-safe locking devices as described above wherein the primary 
locking members or elements are locked in the extended positions thereof. 
In connection with the embodiment or arrangement shown in FIGS. 12 and 13, 
the locking device must be modified as suggested above to lock the primary 
locking element or shaft portion 10b in the retracted position thereof. 
In the description of bobbin supporting shafts incorporating the fail-safe 
device of the present invention, the shafts have all been shown (FIGS. 
10-15) as being normal to the axis of rotation of the tubular frame 148. 
However, this description was only by way of illustration, and clearly, 
the fail-safe locking device can be used on any cantilevered shafts of a 
reel supporting system. This includes reel supporting shafts normal, 
parallel or at any intermediate angular inclination relative to the axis 
of rotation of the machine. The same is true of the reel engaging means 
which are shown in FIGS. 10-15 and described above. It will become evident 
to any artisan skilled in the art that the basic fail-safe locking device 
may be made to cooperate with numerous types of reel engaging means, 
pintles and the finger or prong arangements shown being only illustrative. 
It is to be understood, therefore, that the foregoing description of the 
various embodiments illustrated herein is exemplary only, and various 
modifications to the embodiments shown herein may be made without 
departing from the spirit and scope of the invention.