Note: Descriptions are shown in the official language in which they were submitted.
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la67l2~ ,
The present invention relates to a latch bolt sub-
assembly for a door lock.
Although there has recently been great stress laid
upon the security feature of locks there are sundry types of
S in~tallations where security i9 not of primary consequence.
Despite the lack of stress on the security feature, locks
for such purpose do need to be dependable, namely to open
and close when needed, in a reliable fashion, for long peri-
ods of use. Some installations also have need for what is
commonly known as a privacy lock, namely one which can be
locked or blocked on the inside for temporary security but
which can be released from the outside, in case of an emer-
gency, by some conventional tool such as a screw driver or
ice pick, for example. Installations of the type suggested
are often adequately supplied by locks of less costly con-
struction and where installations can be quickly and easily
made by persons of no more than modest skill. Areas where
such locks are in demand include interior door6 of recreation
vehicles, campers, trailers, temporary housing, closet doors
and the like where a door needs to be shut and held shut but
wherein no attempt iB made to provide a lock greatly resist-
ant to tempering and unauthorized entry.
With the advent of dependable synthetic plastic
resin material there has been a-progressive substitution of
the pla~tic resin material for some of the working parts of
locks. By proper design more and more of the metallic com-
ponents of a lock can be dispensed with in favor of plastic
components. The fact remains, however, that pla.~tic material
does have limitations in that it cannot be made in sections
as thin as metallic material and on other occasions falls
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1~67:1ZO -`
short of the strength which might be required. Moreover
if full advantage is to be taken of the use of plastic
material it is important to minimize the number of separ- :
ate components without sacrificing the number of functions :~
performed by each so that such a lock made substantially
of plastic components can be molded of relatively few parts
and sold in great quantities therefore at an acceptable -
price advantage. .: :
It is therefore an object of the invention to
provide a latch bolt sub-assembly wherein spring means for
retuxning the latch bolt to extended lateral position is :~
inherently built into the parts making up the latch bolt
sub-assembly.
The present invention accordingly provides a
latch bolt sub-assembly for operation with a spindle hav- .
ing edge means rotatable about an axis of rotation, said
sub-assembly comprising a tubular case member having an ~-
outwardly facing opening and an inwardly acing opening
and a latch bolt member having a shaft slidably mounted
in said case member, said shaft having roll back means
at one end for engagement by the spindle and a latch bolt
head at the other end, one of said members com~rising a .~
cam track having an incline relative to the long axis of :
the latch bolt member, the other of said members having .
resilient finger means of synthetic plastic resin material
with one end anchored and an opposite free end in sliding
engagement with said cam track, whereby to provide a re-
silient force acting in a direction urging said shaft to
an extended position, and an auxiliary spring element
having one portion anchored between the cam track and the
--3--
`: :
., ` 10671,2~ : .
free end of the finger means another portion of said
auxiliary s~ring element having a spring kept engagement
with said casé member.
The present invention also provides a latch
S bolt sub-assembly for operation with a spindle having edge
means rotatable about an axis of rotation, said sub-assem-
bly comprising a tubular case member of synthetic plastic
resin material having an outwardly facing opening, an in-
wardly facing opening, and a cylindrical guide bore there-
through between said openings, and a latch bolt member
having a shaft slidably mounted in said case member, said
shaft having roll back means at one end for engagement by
the spindle and a latch bolt head at the other end, said
latch bolt member comprising a cam track having an incline
relative to the long axis ~f the latch bolt member extend-
ing from the bolt head radially inwardly toward the long
axis of the latch bolt member , said tubular case member
having resilient finger means comprising a cut out portion
of the wall of said case member with one end anchored and
an opposite free end extending toward said outwardly fac-
ing opening and biased normally into the interior of said
case member and in sliding engagement with said cam track,
whereby to provide a resilient force acting in a direction
urging said shaft to an extended position.
The present invention further provides a latch
bolt sub-assembly for operation with a spindle having
edge means rotatable about an axis of rotation, said
sub-assembly comprising a tubular case member of synthetic
plastic resin material having an outwardly facing opening
and an inwardly facing opening and a latch bolt member
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having a shaft slidably mounted in said case member, said
shaft having roll back means at one end for engagement ~ -
by the spindle and a latch bolt head at the other end,
said latch bolt member comprising a cam track having an
incline relative to the long axis of the latch bolt member,
said tubular case member having resilient fin~er means :
comprising a portion of the wall of said case member with
one end anchored and an opposite free end biased normally
into the interior of said case member and in sliding en- - .
gagement with said cam track, whereby to provide a resil- -
ient force acting in a direction urging said shaft to an . .
extended position wherein there are two cam tracks on
diametrically opposite sides of the respective member and : .
a corresponding finger means for each cam track there be- ~
ing a generally U shaped auxiliary spring element having
a free end of one leg of the spring element anchored be-
tween one cam track and the corresponding free end of the :
finger means and a free end of the other leg of the
spring element anchored between the other cam track and ~:
the corresponding free end of the other finger means.
The latch bolt sub-assembly may thus be made
of substantially all plastic components wherein a metal-
lic spring for returning the latch bolt to extended pos-
ition has
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1067~.z~)
been dispensed with in favor of a new and Lmproved plastic
return mechanism with virtually a minimum number of indivi-
ual separate components. The latch bolt of plastic material
may therefore be such that the resiliency of the material
S serves to extend the latch bolt and also to return the knobs
to initial position, the spring structure being such that it
can be varied by provision of a single piece auxiliary spring.
In the accompanying drawings:
FIGURE 1 is a fragmentary per~pective view of a
section of door showing the plastic privacy lock installed;
FIGURE 2 is a longitudinal sectional view on the
line 2--2 o Figure l;
FIGURE 3 is an exploded perspective view of all
the individual parts;
- 15 FIGURE 4 is a right end elevational view on the
line 4--4 of Figure 2;
FIGURE 5 is a cross-sectional view on the line
5--5 of Figure 2;
FIGURE 6 is a cross-sectional view on the line
6--6 of Figure 2;
FIGURE 7 is a longitudinal sectional view of the
inside locking assembly in unlocked position of the push-to-
lock form of the device;
FIGURE 8 is a longitudinal sectional view of the
inside locking assembly on the line 8--8 of Figure 7;
FIGURE 9 is a fragmentary longitudinal section view
of the inside locking assembly parts in locked position;
FIGURE 10 is a cross-sectional view on the line
10--10 of Figure 8;
FIGURE Il is a cross-sectional view on the line
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~:,
11--11 of Figure 8 but with the knob pushed to locked posi-
tion;
FIGU~E 12 is a fragmentary enlarged cross-sectional
view of a privacy lock form of the device showing the locking .~ ..
detent; J `.-
FIGURE 13 i8 a longitudinal sectional view on the -:
line 13--13 of Figure 12; .
FIGURE 14 is a longitudinal sectional view of the
latch bolt sub-assembly in extended position on the line
14--14 of Figure 2;
FIGURE 1S is a longitudinal sectional view on the :.
line 15--15 of Figure 14. . -
FIGURE 16 i9 a longitudinal sectional view similar
to Flgure 15 but in retracted position; and
FIGURE 17 i8 a longitudinal sectional view of the
latch bolt qub-assembly during insertion into the door. ~.
In an embodiment of the invention chosen for the .`
purpose of illustration, a lock is shown in Figures 1 and 2
installed on a door 10 which has an o.utside facs 11, an in-
side face 12 and a side edge or.edge face 13. An opening 14
extends through the door between the outside and inside faces.
A bore 15 extends from the edge face 13 into the opening 14.
The door 10 is adapted to swing against.a door stop 16 in a .-.
door frame 17, the frame being provided with a conventional
strike plate 18 having the customary latch bolt opening 19
in it. The parts described up to this~point are found on
virtually all types of doors in which the door lock of the
invention is installed.
In the illustration embodiment there are seven
parts for the door latch all of which are individually shown
lQ671ZO
in Figure 3 together with a conventional mounting screw 25.
All parts o the latch are of a synthetic plastic resin
material except for the spindle 32 and the mounting screw 25
which, in the present embodiment are of metal. An outside
S sub-assembly consists of an outside knob 26 and outs~de rose
or mounting plate 27. An inside sub-assembly consists of an
inside knob 28 and inside rose or mounting plate 29. A latch
bolt assembly consists of a case 30 and latch bolt 31. All
parts of the sub-assemblies just described are constructed
of an appropriate synthetic plastic resin. Cooperating with
the outside and inside sub-assemblies is a spindle 32 which
i9 preferably metal but which can be of an appropriate plas-
ti¢ material.
As shown in Figure~ 2, 3, 4, and 5 the outside
knob 26 has an lnside end 36 in which is an annular recess
37 formed by inner ends 38' of fins 38 and the wall 39 of a
sleeve-like protruberance 40. The protruberance 40 stiffened
by fins 40' extends axially inwardly of the inside face 36.
Concentrically disposed within the p~otruberance 40 is an
inner sleeve 41, at the inner end of which i9 an arcuate
projection 42 separated from the remainder of the inner
sleeve 41 by a recess 43. The recess forms an outwardly
facing shoulder 44 and an inwardly facing shoulder 45. By
rea~on of the character of the material and the length of
the inner sleeve there is a degree of flexibility.
The outside rose 27 has an annular rim 46 which may
be pitched slightly inwardly so that its outside edge may
~it~ slightly into the outside face 11 of the door. Extend-
ing axially outwardIy from the rim is a bearing sleeve 47
having an inside bearing surface 47'. The bearing sleeve
lQ67120 ~:
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extends into the recess 37 where the wall 39 on the pro-
truberance 40 is adapted to bear as the knob is rotated re-
lative to the rose. A boss 48 is an extension of a centrally
disposed mass 51 molded integrally with the rose 27 to which
the mass is attached by sundry radially disposed fins 52
and associated fins 55, 55'. The mass 51 and portions of
the fins 52 project inwardly relative to the outside face 11
of the door. An enlarged arcuate clearance 32' in the out-
side rose provides room for the spindle to rotate.
Extending inwardly into the inside knob 28 from an
inside end 56 is a series of recesses 57 each formed by a
wall 58 of a fin 53 and the exterior of a somewhat sleeve-
like protruberance 60. Alternate fins 54 are cut deeper.
At the inner end of the protruberance 60 is an arcuate pro-
jection 62. The projection is separated from the remainder
of the protruberance by a relatively wide recess 63 which
provides~an outwardly facing shoulder 64 and an inwardly
facing shoulder 65.
on the inside rose 29 is an;annular rim 66 which
i8 adapted to bear against the inside face 12 of the door.
Thi-q rim also may be pitched slightly inwardly so that its -
outside edge may bite slightly into the face 12 of the door
and ensure contact of the rim structure 66' also with the
face of the door. Extending axially outwardly from the in-
side rose 29 is a bearing sleeve 67 which projects deeply
into the recess 57 of the inside knob 28 to a position where
it is adapted to bear rotatably against the wall 59. An-
arcuate bo~s 68 provides an arcuate surface 69 in a position
adapted to bear against the bottom of the recess 63 and also
iO to provide an axially outwardly facing shoulder 70 adapted
10671Z~) -
to engage the inwardly facing shoulder 64 of the knob. An
axially inwardly facing shoulder 71 is adapted to engage the
outwardly facing shoulder 65 of the inside knob. As will be
observed from the drawings, particularly Figures 2 and 7,
the width of the recess 63 is substantially greater than the
width of the boss 68 so that the inside knob 2~ can shift
axially an appreciable amount.
Also on the inside knob 28 are locking legs 75 and
75' best shown in Figures 8, 9, and 11. The locking legs 75
and 75' are resilient and have at their respective inner ends
beads 76 and 76' separated axially in one direction from ~'
respective ends 77 and 77'. The beads 76 and 76' are adapted
to ~lide over a boss 78 and enter respective channels 79'
behind the corresponding locking lugs 79 in an inwardly ex-
tended locked position of the inner knob 28, as shown in
Figure 9.
To understand the locking arrangement reference is
made to Figures 3 and 7 of the drawings where there is shown
a series of circumferentially spaced.axially inwardly ex-
tending notches or slots 81 at the edge of the bearing sleeve
67. Those portions of the fins 53 at the bottoms of the
recesses 57 of the inside knob are adapted to project into - ~-
the respective notches 81, when the inner knob 28 is pushed
inwardly to the position shown in Figure 9. By having the
~leeve-like protruberances 60 slide snuggly within the in-
terior bore 83 of the bearing sleeve 67 the locking beads 76,
76' are effectively centered with a minimum amount of wear.
The interlocking relationship locks the inner knob
again~t rotation. When the inner knob is projected inwardly
from the position of Figure 8 to the position of Figure 9,
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,:
the beads 76 and 76' are flexibly deflected by the locking
lugs 79 until they override the locking lug and are releas-
ably detined in the inwardly extended position, namely the
position in which the respective fins 53 are in the notches -
Bl. In addition the sleeve 60 has a semicircular segment
72, the edges of which must align with corresponding edges
of the arcuate boss 68 before the fins 53 can enter the
notches 81. The breadth of the recess 63 is made such that
it will accommodate an axial movement sufficient to accom-
plish the locking just described.
Conversely when the inner knob is to be unlocked
it is merely pulled outwardly during which movement the beads
76 and 76' are again deflected over the locking lugs 79 from
thè position of Figure 9 to the po~ition of Figure 8 wherein
the fins 53 and segment 72 are d~sengaged. In the outer
position o Figure 8 the inner knob is still in rotatable
engagement with the inside rose 29 by reason of the sliding
fit of the protruberance 60 in the bearing sleeve 67.
In unlocked position ends o~ the fingers beyond
the beads 76, 76' overlie the annular locking lug 79 80 that
when the knob is pushed upon the fingers 75, 75' do not hang
up and cause the fingers to buckle.
For anchoring the two roses in position on the
- door and engagement with each other there is only the single
screw 25 already identified. In the outside knob there i~ a
central pas~ageway 85 larger in diameter than the head of
the screw to which access i8 had for a scxew driver through
a hole 86 in an end wall 87 of the outside knob. The hole
86 is preferably smaller than the head of the screw.
In the mass 51 of the outside rose there is a
1067:120
passageway 88 in axial alignment with the passageway 85 hav-
ing a diameter large enough to snuggly acco~unodate the screw.
A web or protrusion of material in the passageway 88 (not
shown) may be employed to temporarily hold the screw 25 out
of engagement with, but in alignment with, a screw hole 90
in a mass 89 of the inside rose 29. A flared openmg 91'
serves to direct the screw 25 into the hole 89. The screw
hole 90 is small enough 80 that a thread forming screw like
the ~crew 25 can be employed to thread its way into the screw
hole 90 to hold the parts together. By making the hole 86
smaller than the head of the screw the screw can not fall
out and get lost. The two sub-assemblies are attached to-
gether in this fa9hion and at the same time the parts are
fastened in position on the door.
There is appreciable reinforcing structure forming ~ -
part of the inside rose 29 embodied in arcuate walls 91 and
92 and straight walls 93 and 94 as shown advantageously in
Figure 10. Surfaces 93' and 94' on the respective walls 93,
94 slidably accommodate the corresponding arms 112 and 113
of the latch bolt 31. Circumferentially spaced radially ex-
tending fins 95 interconnect the walls 91, 92, 93 and 94
with the mass 89. Other circumferentially spaced and radi-
ally extending fins 66' interconnect the walls 91, 92, 93,
and 94 with the rim 66 of the inside rose, as shown in
Figure 10. Edges 101 of the wall 92 engage slots 102 in
the latch bolt case 30 to hold parts together. A dove tail
fit as shown inhibits disengagement.
An arcuately extending space 103 formed in part by
a wall section 104 of the inside rose provides for rotation
of the spindle 32.
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To prevent the inside ro`se 29 from rotating rela-
tive to the out~ide rose 27 after they have been anchored in
po~ltion as previously described channel sections 97 and 97'
are provided on the outside rose 27 and these are adapted to
S be received in respective complementary pockets 98 and 98'
on the inside rose. Further still to center the inside rose ~`
in the opening 14 in the door and by this center of the en-
tire assembly, outside surfaces of the pockets 98 and 98'
and the arcuate walls 91 and 92 have substantially the same
curvature as the opening 14.
To accommodate the spindle 32 there i8 provided in ~-
the inside knob 28 an arcuate pocket 105 which has a cross
sectional area and size complementary with respect to the
cross sectional area and ~ize of the spindle 32. The spin-
dle is additionally provided with a pair of projections 106
which establish a frictional engagement with the walls of
the arcuate pocket so that once the spindle has been pushed
into position in the inside knob it will not readily fall
out. Similarly the outside knob 26 i;s provided with an
arcuate pocket 107 into which the outside end of the spindle
32 can freely enter. The spindle i3 of such length that one
end 108 bottoms against an end wall 109 of the inside knob.
No attempt i8 made to have the opposite,end of the spindle
bottom against the end wall 87 of the outside knob 26 be-
cause when doors of different thickness are encountered the
position of the spindle 32 in the arcuate pocket 107 changes.
When the knobs are interconnected by the spindle 32 as de-
scribed both rotate simultaneously when one or the other is
rotated.
In essence rotation of the knobs is for the purpose
1t~671Z6)
of withdrawing the latch bolt 31 and thereafter permitting
it to return to extended position. The latch bolt is speci-
ally constructed for this purpose. As shown in Figures 3,
14, and 17 the latch bolt con~ists of a shaft member 110 at
one end of which is the latch bolt head 111 of customary
design. The other end of the shaft 110 is bifurcated to pro-
vide a pair of resilient arms or bolt tails 112 and 113. The
resilient arm 112 has a shoulder 114 facing the spindle 32
at an adjacent edge 115. Adjacent the shoulder 114 is an
oblique camway 116 along which the edge 115 of the spindle 7
i~ adapted to travel. Similarly on the resilient arm 113 i8
a shoulder 117 adjacent an opposite parallel edge 11~ in the
spindle 32 with a similar camway 119 along which the edge
118 is adapted to travel. When the spindle is rotated by
opexation of one or the other of the knobs from the position
of Figure 15 to the position of Figure 16 the latch bolt
head 111 i9 withdrawn subject to subsequent extension by
appropriate spring action.
It should be noted, however;, that ends 120 and 121
of the respective resilient arms are spaced wide apart and
do not encompass the screw 25 except at the innermost ex-
tension of the latch bolt as shown by the broken lines in
! Figure 14. Notches 109 in the case 30 ~eceive arms 112, 113
when the latch bolt shaft is extended.
As shown in Figure 17 there is sufficient clearance
between the arms 112 and 113 to permit them to be forced to-
gether close enough to permit the latch bolt to be passed
through the door edge bore 15 of substantially minimum dia-
meter~ To adequately confine and position the arms 112 and
113 the outside surfaces are made to slide along complementary
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10671Z0
.:
surfaces 93' and 94' respectiveLy of the walls 93 anl ~,
see Figure 14.
To provide the necessary spring action to return
the latch bolt to extended po~ition there are provided on
the case 30 a pair of spring legs 123 and 124. These spring
legs are made of the same material as the case 30 and are in
effect cut out of the wall of the case. The legs terminating
respectively in free ends 125 and 126 extend inwardly into a ~
guide bore 127 of the case, see Figure 3. Immediately at .-
the rear of the bolt head 111 there are two ramps 128 and
129 back to back which converge to an inner end 130.
Although a separate spring element 160 is shown th~
legs 1~3, 124 may be effectively employed to e~tend the :~
shaft without assistance of the spring element 160.
When the spring element 160 is not employed the
end 125 of the spring le~ 123 is adapted to ride on the ramp
128 and the end 126 of the spring leg 124 is adapted to ride
on the leg 129. There is additionally provided ramps 131
and 131' at a steeper angle adjacent.,the inner end 130 which
serve to more effectively build up spring tension during
initial withdrawing movement of the latch bolt 111. This
compensates for a diminishing effectiveness of the spring
legs 123 and 124 as they approach their relaxed position with .
the shaft fully extended.
A shoulder 129' at the head end of the ramp 129
by engagement with the end of the respective finger 124 pre-
vents inadvertent disassembly of the shaft member 110 from
the case 30.
When the latch bolt including the latch bolt head
is withdrawn by rotation of the spindle the ends 125 and
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126 slide up the respective ramps 128 and 129 building up ~ -
tension in the spring legs 123 and 124 as they approach
opposite ends of the ramps. ~hen the spindle is released ~,
energy built up in the spring legs causes them to press
S against the respective ramps and by this pressing or squeez- ~
ing action to extend the latch bolt head outwardly again to -
- the position shown in Figures 21 and 22.
- Occasions may arise when a stronger spring action
i9 desirable to extend the latch bolt shaft or for example,
to return the knobs to initial position after they have been ~ -
rotated to withdraw the latch bolt. The spring element 160 ; -
serves this purpose. In a modified U shape spring legs 161
and 162 are joined at one end'by a transverse portion 163.
The opposite free end of leg 161 has a foot 164 and the leg
162 a foot 165. The spring element is inherently biased so
that the feet 164 and 165 are pressed together with an ap-
propriate amount of spring tension.
Positioned as shown in Figures 15 and 16 the end
125 of the leg 123 is lodged in the angle formed by the foot
164 with the corresponding spring leg l61. The end 126 is
similarly lodged behind the foot 165. As a consequence when
one or the other of the knobs are rotated to withdraw the
latch bolt from the position of Figure 15 to the position of
Figure 16 there is greater resistance to rotation offered by
the combined spring tension of two legs 123, 124 together
with the spring legs 161 and 162. This greater spring ten-
sion is available to subsequently return the knobs to initial ;
position and to extend the latch bolt.
Although a spring element may have various effec-
tive shapes for supplementing action of the legs 123 and
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lQ67J~20
124, a single piece U shaped element is especially advan-
tageous. When assembled in the latch bolt case the spring
element is preferably lnserted in the orientation shown in
Figure 3 into the space between the resilient areas 112, 113
until the feet 164, 165 engage the corresponding ramps of
the shaft 110. Then when the shaft is projected into the
case 30 the ends of the legs 123, 124 snap over the feet and
the spring element becomes locked in as shown in Figure 15.
In this form of the device the material of the spring ele-
ment 160 actually engages the ramps rather than the material
of the legs. Otherwise action of the legs is the same as
has been initially described.
Although a metal spring element 160 has been shown
for the purpo9e of illustration other spring material may be
employed such as an appropriate synthetic plastic resin, with
or without reinforcement. A desired tension may be built
into the spring element depending on desirable performance
requirements of the latch.
To prevent ends of the spring legs from shifting
laterally, tear drop projections 166 and 167 may be formed
at respective ends of the legs 125 and 124 providing a space
between the projections 166, 167 for accommodation of the
ends of the spring legs.
For locking the plastic lock when-it is structur-ed
as a privacy lock as described in detail, locking accom-
plished when the spindle is locked against rotation. To so
lock the spindle the inside knob 28 is pushed inwardly as
has been previously described. Should the door be inadvert-
ently locked when in the open position no damage is done to
the lock set should the door be closed and the latch bolt be
1~67~ZO ':
driven back because movement of the arms 112 and 113 will
not be impaired by either the spindle 32 or the screw 25.
For unlocking the lockset from the ~utside ~ the
door, more commonly known as emergency release, there is
provided an opening 135 in the end wall 87 of the outside ~
knob 26, the opening being in alignment with the spindle 32. -
An appropriate tool such, for example, as a rod I36 can be -~
inserted through the opening 135 and pressed against an ad~
jacent end edge 137 of the spindle 32 which in turn pushes
against the end wall 109 of the inside knob 28 causing the
beads 76 and 76' to be disengaged from the annular lock lugs
79 at which time the fins 53 are disengaged from the notches
or slots 81, and the segment 72 is disengaged from the edges
of the arcuate boss 68. As a result the ins~de knob 28, and
the outside knob 26 as well, are then free to be rotated for
withdrawal of the latch bolt. A slot 134 in the inner sleeve
41 serves to suide the rod 136 as it is pushed against the
spindle 32 and a step 138 in the end edge of the spindle
also helps center the rod 136 in alignment with the spindle.
A~ shown in Figure 4 an end face 140 of the out-
side knob 26 can be provided with a design presenting a
series of blin~ recesses 141 which are similar in appearance
to the opening 135. Sundry varied designs may be selected.
An end face 142 of the inside knob 28 may carry a comparable
design.
Prior to assembly of the outside rose and knob
with the inside rose and knob on the door the latch bolt is `
inserted. The spindle then is projected into the space be-
tween the resilient arms 112 and 113 of the latch bolt. The
case 30 is effectively interlocked with the other working
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~ . . . . ~ ... . -
1~:t67~20
parts and secured in the appropriate rose in the door by
interlocking dovetail edges 101. of the rose 29 with the dove~
tail slots 102 of the case 30. It follows, therefore, that
all of the component parts are attached to each other and -
S in proper position on the door in a quick, single operation
by merely assembling them in position in the door and then
securing them by employment of a single screw.
In each instance the knob, whether outside or in-
side knob, may be preassembled on the corresponding rose in
a manner permitting disassembly whenever necessary.
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