Note: Descriptions are shown in the official language in which they were submitted.
Description
Safety Turnstile
Field of Invention
This invention relates to the mechanism of a turnstile. In particular it
5 concerns a smoothly turning continuous motion t~ tile, suitable for either
clockwise or counter-clockwise unidirectional rotation, resistant to freewheel
spinning and capable of being easily disengaged in an emergency to permit
reverse motion.
Background Art
Turnstiles have long been known. Commonly they involve a gate
which rotates only in one direction about an axis, operating in co-operation
with an adjacent barrier. They permit passage of persons or ~nim~l~ in one
direction only. Turnstiles are known with internal gearing, coin or ticket
operation, mechanical detents, and the like.
Children often enjoy playing with turnstiles. In some in~t~nres children
try to spin the turnstile as quickly as they can, and may injure themselves withor in the rotating structure. In particular, children may be prone to climb
upon, and trap themselves between, the rotating parts of the turnstile and an
adjacent barrier. The turnstile can only turn in one direction, so it can only
20 become more tightly jammed as a child struggles.
Presently known turnstiles may be released by use of electric solenoids
to disengage an internal gear mech~nism, or by swinging the entire turnstile
out of the way.
One type of common turnstile employs a solid machined block fit into
25 the top of a hollow support column. The machined block is adapted to seat a
pair of one way roller or needle bearings such that the rotating member can
only turn in one direction. This embodiment has several disadvantages. First,
the turnstile cannot be adapted to turn in the opposite direction without major
disassembly to permit the block and bearings to be installed in the opposite
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direction. Second, the bearings may be inadequately suited to eccentric loads
applied, for example, when adults place extreme force on the arms of the
turnstile. Third there is no emelgell~y release. If a child is jammed in the bars
it may be nPcess~ry to unbolt the entire assembly from the floor. Fourth, the
5 block is held in the shaft by a single screw. Over time the block may begin
to shift back and forth in the shaft, rotating about the axis of the screw.
As turnstiles are often used by children as toys they are often subject
to abuse. Thus there is a need for a safety turnstile which may be easily
released, may turn in either direction, will resist high speed spinning, and
10 which is sufficiently rugged to survive moderately abusive tre~tmP-nt
Further examples of prior art for turnstiles include United States Patent
No. 5,072,543 which relates to a t~ tile made with a stationary tl~rn~tile
support shaft extending from a solid support, and a bearing on the end of the
shaft. The turnstile hub is supported on the end of the shaft with a bearing.
15 The tllrn~tile hub is locked against rotation in a fee-paid direction by a
unidirectional pawl that engages a cutout on a ratchet plate att~ch~d to the
hub. The unidirectional pawl is released by ell~ g a solenoid latching
mech~niim .
In addition, United States Patent No. 3,978,613 relates to a tl~rnstile
mech~ni~m comprising a rotatable hub adapted to be driven by a person using
a tllrn~tile~ the hub being conn~cted to (or incorporating) a disc formed with
a number of stop surfaces which are engageable by a stop member which is
movable between a first position clear of the path of the stop surfaces and a
second position lying in the path of the stop surfaces.
Further, United States Patent No. 3,914,902 relates to a tllrnctile which
includes a turnstile head pivotally mounted on a support for rotation about an
axis defined by the support. A shaft is journaled in the turnstile head and a
hub is keyed to the shaft for the rotation thereof responsive to the rotation ofthe hub. Arms carried by the hub radiate th~l~;fiolll in a conical formation,
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and when indexed in the home position, one of the arms is disposed in a
subst~nti~lly horizontal passage barring position while the rem~ining arms are
disposed in a substantially vertical position. A spur gear is keyed to the shaftat the end thereof opposite the end portion to which the hub is keyed and is
S in meshed relationship with a pinion gear which is journaled in the turnstile
head and which is provided with a roller clutch which allows for rotation of
the pinion gear in a single direction only. Three depending roller cams are
disposed about the periphery of the spur gear which is aligned on the shaft so
that the roller cams are subst~nti~lly radially aligned with the extending arms
10 carried by the hub.
United States Patent No. 3,383,797 relates to a turnstile l1tili~in~ a cam
controlled assembly.
Summary of the Invention
The present invention provides a safety turnstile suitable for either
15 clockwise or counter-clockwise rotation, which is resistant to freewheel
spinning, and which may be released easily. In one aspect of the invention
described herein a turnstile is provided which comprises a stator assembly; a
rotor assembly coaxially mounted about the stator assembly for pivotal motion
about the stator assembly; adjustment means to position the rotor assembly
20 relative to the stator assembly normally to the pivotal motion, the stator
assembly comprising one of: (a) a bearing surface or (b) at least one drag shoe
assembly, the rotor assembly colllplishlg the other of: (a) at least one drag
shoe assembly or (b) a bearing suRace, the adjustment means adapted to be
adjusted from a first position in which the drag shoe assembly is ~ çng~ged
25 from the bearing surface to a second position in which the drag shoe assemblyrests against and an.gularly engages the bearing surface, whereby in the second
position pivotal motion of the rotor assembly in a first direction of rotation
with respect to the stator assembly is accompani~d by sliding engagement of
the at least one drag shoe assembly with the bearing surface and pivotal
30 motion of the rotor assembly in a second, opposite, direction of rotation with
4 --
respect to the stator assembly is accompanied by j~mming of the drag shoe
assembly against the bearing surface.
In a further aspect of the invention the turnstile comprises a quick
S release mechanism wherein the quick release mechanism comprises a quick
release wrench and a gripping means, such as a threaded bolt of the turnstile
adjustment means having a through hole, whereby a cylindrical shaft of the
quick release wrench is introduced through the through hole to facilitate
loosening of the threaded bolt.
10 Brief Description of Drawings
Figure 1 is a perspective general view of a turnstile according to the
present invention;
Figure 2 is a cross-sectional view of the turnstile of Figure l;
Figure 2a is a cross-sectional view of the second embodiment;
Figure 2b is a side view of the second embodiment;
Figure 3 is a perpendicular view of the internal assembly of Figure 2
showing a drag shoe assembly of the present invention in a disengaged
position.
Figure 4 shows the drag shoe assembly of Figure 3 in a position in
20 which it is engaged to permit clockwise rotation of the turnstile.
Figure 5 is a partially sectioned plan view of the internal assembly of
the turnstile of Figures 1, 2, and 4.
Figure 6 shows a second embodiment of the turnstile of Figure 2.
Detailed Description of the Best Mode for Carrying Out the Invention
As shown in Figure 1, a turnstile assembly is shown generally as 2. It
comprises a stator assembly 4, which is by definition stationary, and a rotor
assembly 6 mounted coaxially with, and for pivotal motion, or rotation, about,
the stator assembly 4. Also shown in Figure 1 are a pillar 8, floor mounting
means 10, and a turnstile housing 12 comprising an upper shell 13, and a
30 lower shell 14.
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As shown in Figure 2, the stator assembly 4 comprises pillar 8, floor
mounting means 10, a main shaft base plate 16, a main shaft 18, a pin 20, a
flat spring 28 and a lower friction plate 30. The upper part of the stator
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assembly 4 further comprises a safety top bolt 32, and a cap washer 34 to
which a l~hL~olcillg flat washer 36 has been welded. This reinfol~;ed cap
washer may be replaced by a solid m~l~hinPd fitting or other equivalent such
as would be known to those skilled in the art.
S The rotor assembly 6 comprises, in addition to housing 12, arms
shown generally as 40, a main rotor tube 42, a rotor bottom washer 44, a
rotor intermediate plate 46, arm retainers 48, a machined Ultra High
Molecular Weight Polyethylene, or UHMW, rotor bushing 50, and at least
one rotor drag pin 52. Those skilled in the art will appreciate that materials
10 other than UHMW may be used for rotor bushing 50.
In the p-efelled embodiment shown herein rotor assembly 6 further
comprises at least one drag shoe assembly, shown generally as 60, itself
comprising a drag arm 62 and a drag foot 64. Other embo-liment~ of the
invention disclosed herein are possible in which stator assembly 4 comprises
lS drag shoe assembly 60 or a functional equivalent thereof.
The pillar 8 is mounted to a suitable floor by the floor mounting means
10 rigidly affixed at its lower end. The floor mounting means 10 may be
welded to the pillar 8 or f~tenPd thereto by rivets, threaded f~tenPrs or other
known structural attachment methods. The floor mounting means may be
20 adapted, for example, to accept threaded studs embedded in the floor. Many
such means are known.
As shown in Figure 2, the main shaft base plate 16 is ~tt~r-hPd to the
upper end of pillar 8 by means such as welding, and rests substantially parallelto the chosen floor surface. Located centrally in, and extending upwardly
25 from, base plate 16 is the cylindrical main shaft 18, which is substantially co-
axial with the longitu-1in~l axis of pillar 8. Again, welding is the pr~felled
fastening means although many other means are known. The flat spring 28 is
substantially square with clipped corners and has a generally centrally located
aperture (not shown) which permits it to slide over the main shaft 18 and to
30 rest with two opposite peripheral edges in contact with base plate 16. The
lower friction plate 30 is also provided with a central apellu,e (not shown) to
permit it to slide down over the main shaft for inst~ tion in contact with the
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upper face of the flat spring 28. To prevent the lower friction plate 30 turningabout main shaft 18 the pin 20 is recessed into base plate 16 and extends
upwardly thelcrlolll to traverse and engage an indexing clearance hole (not
in~ t~d) in lower friction plate 30.
The upp.,llllost end of main shaft 18 has a blind drilled and tapped hole
54 adapted to engage the threaded shaft of the safety top bolt 32. The lower
face of the head of safety top bolt 32 bears upon the upper surface of flat
washer 36, welded, as noted, to cap washer 34. A lock washer, not shown,
may be inserted between safety top bolt 32 and flat washer 36. As will be
10 described in greater detail below, when the t~lrnctile 2 is assembled the rotor
assembly 6 is captured between the lower face of cap washer 34 and the upper
surface of the lower friction plate 30.
In rotor assembly 6 the rotor bottom washer 44 is fixedly attached
centrally about the lon~ibl~in~l axis of, and perpendicularly to, the main rotor15 tube 42. The rotor intermediate plate 46 is fixedly located about, and co-axial
with, the main rotor tube 42 and is substantially paMllel to the rotor bottom
washer 44. The length of main rotor tube 42 is chosen to accommodate the
height of the drag shoe assembly 60 when ~ eng~ged, as will be described
below, and to accommodate the arms 40. The main shaft 18 is chosen to have
20 a correspondingly suitable length. Finally, the length of main rotor tube 42
is such that the assembly will resist wear when eccentric loads are applied -
i.e., the bending moment applied when a child swings on the end of an arm.
In the plcrellcd embodiment rotor interrn~ te plate 46 has been located to
permit all of arms 40 to rest shy of the uppermost end of main rotor tube 42
25 when installed.
As best shown in Figure 5, arm retainers 48 are made by forming
strips of metal into right angled bends, and then welding them to the upper
surface of rotor interrn~ te plate 46 radially about the longib~din~l axis of
the rotor assembly on 90 degree arc intervals such that the arms of two
30 adjacent arm retainers 48 are substantially parallel and spaced apart a suitable
~ict~n~e to accommodate the width of, and thereby act as stop for, the arm
40. There are many alternative means for achieving the retention of arms 40
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such as would be well known to those skilled in the art. In the plcfell~d
embodiment each of the four arms 40 is welded to the arm retainers 48.
Drag pin 52 is aligned radially from the longihl(lin~l axis of rotor
assembly 6 and is fixedly attached to rotor intermediate plate 46. In the
5 prefelled embodiment each drag pin 52 is 3/8 inches in diameter and is
located in each of four locations at 90 degree arc intervals.
Rotor bushing 50 is machined from UHMW material to fit within main
rotor tube 42 and to mate slidably with main shaft 18.
Drag Shoe assembly 60 is best shown in Figures 3 and 4. At one
10 extremity drag arm 62 comprises a first cylin~ric~l boss 66 suitable for
slidable location on and pivotal motion about drag pin ~2. Drag arm 62 may
be retained on drag pin 52 by many well known means. In the ~lef~lled
embodiment a cotter pin 68 is shown, with flat washers (not in~ ted) on
either side of the boss to reduce wear. At the other e~llc;lllily dMg arm 62
15 comprises a second cylindrical boss 70 suitable for slidable admission of, and
pivotal rotation about a shaft, or shank. of a ret~ining bolt 72.
Drag foot 64 comprises two subst~nti~lly paMllel upturned tabs, or ears
74, and a sole 76 having a rough~n~d bearing surface, much like the tread on
a the sole of a shoe. In the plefelled embodiment an array of cold formed
20 serrations has been impressed on the sole 76, although many other means for
achieving the same result have been long known. Drag foot 64 also colllplises
a first toe 78 and an opposed second toe 80. Each of the ears 74 has an
aperture located such that bolt 72 may be introduced through one ear, through
boss 70, and through the other ear, like a trunnion in a clevis, thus creating
25 a pivotal attachment of drag foot 64 to drag arm 62. Bolt 72 is then secured
by a locknut 82. In the plefelled embodiment this is a nylon insert locknut.
To assemble turnstile 2, one begins with the stator assembly 4, with
the safety top bolt 32 and cap washer 34 removed. To prevent wear and to
provide normal operational drag between the rotor assembly 4 and the stator
30 assembly 6, an UHMW friction washer 84 is installed about the main shaft 18
with its lower face in contact with the lower friction plate 30. The rotor
assembly 6 including such number of drag shoe assemblies as may be chosen,
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slides down over main shaft 18 to rest with the rotor bottom washer in contact
with the upper face of UHMW friction washer 84. Similarly, to prevent wear
at the upper end of main rotor tube 42, a first flat washer 86 is located about
main shaft 18 abutting main rotor tube 42. A flat thrust bearing 88 and a
5 subsequent second flat washer 90 are stacked on top of first flat washer 86.
Cap washer 34 is installed such that the lower edge of its skirt bears
dow.l~ld on second flat washer 90. Safety top bolt 32 is then threadably
engaged in tapped hole 54. This position, prior to tightening of safety top bolt32 corresponds to the disengaged position shown in Figure 3.
As can be seen in Figure 2, tighte~ g of safety top bolt 32 will cause
conl~lcssion of flat spring 28, as the load imposed by safety top bolt 32 is
carried through cap washer 34, second flat washer 90, thrust bearing 88, first
flat washer 86, main rotor tube 42, rotor bottom washer 44, UHMW friction
washer 84, and lower friction plate 30.
The limit of this tightening will occur when the inner side of cap
washer 34 bottoms on the top of main shaft 18. In this fully tightl nt?~ or
lock-down position the rotor assembly is forced against first flat washer 86 by
the spring preload of flat spring 28. In the ~lefell~;d embodiment this fully
tightened pre-load is roughly 65 Lb. Clearly one may vary the spring to obtain
20 a dirr~r~llL pre-load.
As safety top bolt 32 is tightened the normal force tr~n~mitt~l across
UHMW friction washer 84 increases, causing a corresponding increase in
friction. Turnstile 2 will continue to turn smoothly, but more stiffly. It may
thereby resist rapid spinning by children.
As shown in Figure 3, as safety top bolt 32 first begins to engage
tapped hole 54 each drag shoe assembly 60 will hang with its drag arm 64 in
a substantially vertical orientation from its corresponding rotor drag pin 52.
This may be considered as a first, or ~ çng~ged position. As such the rotor
may be turned easily either clockwise or counter-clockwise.
As safety top bolt 32 is tiEht~nP~ the rough~nç~ sole 76 will come into
contact with base plate 16. Base plate 16 comprises a bearing surface 92 for
this purpose. In the pl~felred embodiment base plate 16 comprises a bonded,
9 -
abrasion resistant rubber drag ring 94 co-axial with the main shaft 18. The
rubber drag ring 94 is sized to correspond to the path traced out by each drag
shoe assembly 60 during pivotal motion of the rotor assembly about the stator
5 assembly, and bearing surface 92 is the upper surface of drag ring 94. The
inner circumference of drag ring 94 is great enough to permit flat spring 2.8
to seat therewithin. Many alternative material combinations would achieve a
similar effect.
If each drag arm 62 is permitted to remain in a vertical orientation
10 while the safety top bolt is tightened the device will not work since furthertightening will only jam each drag shoe assembly into the bearing surface 92.
Thus, as tightening occurs the rotor assembly 6 must be gently turned about
the stator assembly 4 in the direction one wishes the turnstile to operate. Thisturning will also ensure that all drag assemblies lean the same way for the
15 purposes of rotation. If the turnstile is given a sudden jarring impact the shoes
may become disoriented relative to, or flip up from, the bearing surface. A
ring shaped ret~ining spring, 96 is threaded through each drag foot to prevent
this. It acts as a spider and thereby each shoe is limited to a modest angular
displacement.
In use the drag shoe assembly 60 of the pl~fell~d embodiment will be
oriented in a second, locked-down, or engaged, position substantially similar
to that shown in Figure 4 for counter-clockwise rotation. As can be seen,
tightening of safety top bolt 32 has reduced the perpendicular ~ t~n~e between
rotor intermediate plate 46 and base plate 16 such that drag arm 62 is
25 compelled to lie at some acute angle from the vertical, and not perpendicularto base plate 16. This angle is designated in Figure 4 by the Greek letter
alpha. For clockwise rotation angle alpha would be reversed, that is, it would
lie on the other side of the perpendicular centreline of the preferred
embodiment. For the purposes of this specification alpha is the engagement
30 angle of the drag shoe assembly. In the fully tightened pre-load position, orlocked-down angle, of the preferred embodiment of Figure 4 alpha is roughly
22 degrees.
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When rotor assembly 6 is turned in the desired direction of rotation
each drag foot slides easily on bearing surface 92. However, rotation in the
opposite direction causes one or more roughened sole 76 to impart a
compressive component of force into the drag arm, and a tangential
5 component of force to rotate the drag arm to cause angle alpha to decrease.
As a result at least one drag shoe assembly becomes j~mm~, preventing
further rotation. There is little backlash in the assembly because the preload
in the flat spring keeps the rotor assembly snug against flat washer 86 during
normal operation. Thus the tendency to force the rotor assembly 6 upward
10 on the main shaft 18 in reverse motion is limited because the rotor assembly
6 is already against its upper vertical stop, flat washer 86. The jammed
condition may be released either by res-lming rotation in the first direction,
or by releasing the safety top bolt 32.
Angle alpha increases as safety top bolt 32 is tightened toward the
15 lock-down position. Thus the tightening of safety top bolt 32 provides an
adj~lstm~nt, or displacement means adapted to adjust, or displace, each drag
shoe assembly 60 from the first spaced position in which the drag shoe
assembly 60 is disengaged or spaced from bearing surface 92 as shown in
Figure 3, to a second position in which the drag shoe assembly 60 rests
20 against and angularly engages bearing surface 92 as shown, typically, in
Figures 4 and 5. In the second, angularly engaged position pivotal motion of
the rotor assembly 6 in the chosen turning direction with respect to the stator
assembly 4 is accompanied by sliding engagement or dragging of at least one
drag shoe assembly 60 relative to bearing surface 92. Pivotal motion of the
25 rotor assembly 6 in the opposite direction of rotation with respect to the stator
assembly 4 is accompanied by j~mmin~: of the drag shoe assembly 60 relative
to bearing surface 92. It will be noted that the invention described herein willoperate at least temporarily at angles less than the fully engaged, or lock-downangle of the prefelled embodiment in which cap washer 34 bottoms against
30 main shaft 18. One may also increase the lock down angle by locating
additional flat washers between cap washer 34 and second flat washer 90. This
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increases the co,llpression of flat spring 28, and therefore the drag across
UHMW washer 30.
It will be recognized by those skilled in the art that the principles of
the present invention may be applied over a range of values for angle alpha.
5 The range has two limits. First, angle alpha must not be so great that drag
shoe assembly 60 merely skids along bearing surface 92 when the rotor
assembly 6 is turned in the reverse direction (whichever that direction may be
in the cih;~ es). For the purpose of this specification the angular
threshold of this ckidding condition is called the slip angle.
Similarly, alpha must be small enough that drag shoe 60 jams in
reverse motion. This limit will vary with the combination of materials chosen
for sole 76 and bearing surface 92, for example. As alpha approaches zero
the resultant perpendicular force applied in reverse motion may be sufficient
to COlll~)leSS, and displace, bearing surface 92 far enough to permit drag arm
15 62 to swing past the perpendicular, instead of jamming. For the purposes of
this specification this is called the back-over angle. The angular threshold of
this 'back-over' condition will again depend on the m~teri~lc chosen for the
drag shoe assembly 60, bearing surface 92, the tolerances between the various
elements of drag shoe assembly 60, and the force applied to any of arms 40.
20 The forces ~ell~.dted in the j~mming condition may be large enough to deform
cap washer 34. Cap washer 34 is therefore ,eillro,ced by welded flat washer
36. Other reinforcement means are well known. In normal operation a force
of 20 to 40 Lb. will not cause the turnstile of the pler~l~d embodiment to
reverse. However, it may be desirable for the application of a large force by
25 an adult such as, in the case of the pl~re,led embodiment, a force in the order
of 80 or 100 Lb or more, to cause a back over condition in preferellce to
perm~n~nt deformation of the internal elements of the ~lrn~ctile. This
emelgell~y backover also provides a secondary emergel~-;y release function.
As previously stated, the actual force required to cause a backover is
30 dependent upon the materials chosen, the lock-down angle chosen, the
tolerances during m~mlf~cture and the acc~m--l~ted length of time in service.
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It should also be noted that bearing surface 92 need not n~ces~rily be
flat. It is possible to practice the principles of the present invention on a
frusto-conical bearing surface, or even a bearing surface that has a round,
channel, v-shaped or other profile. Similarly, the drag arm need not pivot
5 about drag pin 52 in a precisely vertical plane, but may be suspended at some
angle such that pivotal motion of drag arm 62 about drag pin 52 has a radial
component toward or away from main shaft 18. In all cases the limitation on
the chosen geometry is that it must be such as to cause the drag shoe assembly
60 to jam into the bearing surface in reversed motion, and that gravity, or a
10 biasing device, which may be a spring, cause the drag shoe assembly 60 to
ride upon the bearing surface during rotation in the forward direction,
whichever direction may be chosen.
Once the rotor assembly has been captured by safety top bolt 32, the
upper shell 13 and lower shell 14 are located, for example with threaded
15 fasteners, to form housing 12. Upper shell 13 has a central aperture 15 to
permit a substantial portion of the head of safety top bolt 32 to protrude
beyond housing 12 as shown in Figures 1 and 2. In the plefellcd embodiment,
safety top bolt 32 is thereby made extern~lly accessible.
A second embodiment illustrated in Figure 6 includes an upper shell
20 13 which lacks apelLule 15. In this case the upper shell must first be removed
before an alternate top bolt 33 may be released, ~lt~rn~te top bolt 33 having
a standard hexagonal head suitable for standard wrenches.
In the plcfer~d embodiment top bolt 32 may be grasped and adjusted
by hand. For those who may not have a sufficient grip to release top bolt 32
25 by hand, top bolt 32 has been provided with a through hole 98. Pillar 8
comprises an aperture 100 to admit for storage a quick release wrench 102
having a bent cylindrical shaft (not sepaldtely intlic~te~) and a head 104.
Aperture 100 permits entry of the bent shaft, but not the quick release wrench
head 104. When it is desired to release top bolt 32 quick release wrench 102
30 is taken from its storage position and its shaft is introduced through hole 98.
Through hole 98 provides a gli~ping means adapted to be engaged by quick
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release wrench 102. Wrench 102 may then be turned to loosen top bolt 32. A
first release instruction label 106 is affixed to the head of top bolt 32 to
indicate release by counter-clockwise rotation. Similarly, a second release
instruction label 108 is affixed to pillar 8 near-to aperture 100 to provide
5 emergency release, and readjustment instructions.
In an emergency one may wish to use the first tool which comes to
hand. Therefore, through hole 98 is of a chosen (li~m~ter such that it will
admit not only quick release wrench 102, but also any size of phillips or
robertson screwdriver, small slot headed scle~vdli~ers or other pointed
10 objects.
Thus a tl~ tile of the preferred embodiment does not incorporate
complicated gear, cam, or detent systems, provides smooth operation in either
direction as chosen, and may be easily released if j~mm~(l.
It will be obvious to those skilled in the art that there are other possible
15 embodiments in which the drag shoe assembly may be mounted to a stator
element and the bearing surface may be part or a rotor unit without departing
from the principles of the invention disclosed herein. Similarly, although the
plcfcllcd embodiment incorporates four drag shoe assemblies, it is possible
to practice the principles of the invention with as few as one drag shoe, or as
20 many more than four drag shoes as desired.
