US3484127A

US3484127A - Door securing apparatus

Info

Publication number: US3484127A
Application number: US564105A
Authority: US
Inventors: John V Pastva
Original assignee: Eastern Co
Current assignee: Eastern Co
Priority date: 1966-07-11
Filing date: 1966-07-11
Publication date: 1969-12-16
Anticipated expiration: 1986-12-16
Also published as: GB1182625A; GB1182624A

Description

Dec. 16, 1969 J. v. PASTVA 3,484,1 7

DOOR SECURING APPARATUS Filed July 11, 1966 2 Sheets-Sheet 1 1 N VE N TOR. JOH/l/ 1/. P1457144 BY ficowwwk 5 Bet. 16, 1969 Filed July 11, 1966 J. v. PASTVA 3,484,127

DOOR SECURING APPARATUS 2 Sheets-Sheet 2 INVENTOR. JOHA/ 1/. 2437:,

3,484,127 DOOR SECURING APPARATUS John V. Pastva, Parma Heights, Ohio, msignor to The Eastern Company, Cleveland, Ohio, a corporation of Connecticut Filed July 11, 1966, Ser. No. 564,105 int. Cl. EOSc 3/04, 3/14, 9/18 US. Cl. 292--218 26 Claims ABSTRACT OF THE DISCLOSURE Door securing apparatus, particularly well suited for fastening in closed position the rear doors of truck bodies, comprises a shaft and its actuating means mounted on the door, a keeper member mounted on the door frame, and a latch member, actuable by rotation of the shaft, mounted on the door. The keeper member has two spaced projecting portions of which one has a stem portion and a transverse portion, and the other of which has a free end portion. The latch member has two forks one of which engages beneath the transverse portion of the first projecting portion in straddling relation, and the other of which straddles the second projecting portion. The latch member carries a movable auxiliary securing member that when in securing position engages a shoulder of the second projecting portion to hold the latch member in door securing position with its two forks straddling the two projecting portions.

This invention relates to door lock apparatus for locking doors of vehicles or containers, and more particularly to door lock apparatus of the latch and keeper type having means for positively retaining the latch in locking position in the keeper.

While door lock apparatus of the type to which the invention pertains may be employed for locking the doors of a wide variety of containers or vehicles, it provides particular advantages when employed to lock hinged rear doors of closed trailer van bodies. In such a body, the large doorway at the rear of the body makes it impossible to construct the rear portion of the body stiff enough to prevent, under certain circumstances, racking action of the rear portion of the body in which the top moves or tends to move relatively to the bottom of the body in a path that is transverse to the body and generally parallel to the bottom of the body. For example, such racking action tends to occur if the vehicle is not standing in a level position so that its rear wheels are on different levels; it also tends to occur from twistirg or jostling of the body during travel, particularly at high speeds.

It has been the practice to utilize the doors, when closed, to stiffen the rear portion of the trailer van body: to effect this, door lock apparatus preferably should have a least one latch member on each door engaging a keeper member on the body, at the top and bottom edges of the door, and these latch members should be actuated by a common handle or other actuating means. It is also important that each latch member firmly engages the keeper portion in such manner as essentially to prevent lateral or vertical movement of the door relative to the door frame, and to prevent the latch member from disengaging from the keeper member during transit or otherwise until intentionally disengaged.

Other problems arise when trailer vans are used in services in which they are subjected to relatively high acceleration or deceleration forces, as often occurs in piggyback transportation systems wherein the truck trailer vans are carried on and anchored to railroad flat nited States Patent 0 M 3,484,127 Patented Dec. 16, 1969 cars and in which accelerations and decelerations to which the trailer vans are subjected, as in switching acitivities, may be substantially greater than would be encountered in over-the-road transportation. Often cargoes in trailer vans exposed to higher than normal acceleration or deceleration forces are not anchored to the trailer with correspondingly strengthened anchoring means that can prevent longitudinal movement of the cargo relative to the van toward its rear doors. The moving load can then exert a substantial, and often sudden, force on a rear door, which tends to open the door from the inside. Although prior types of door lock mechanisms, such as that shown in my Patent 3,099,473 over which the present invention constitutes an improvement, have been successful in normal over-the-road service, the imposition on the insides of the van doors of substantial and sudden forces can tend to dislodge at least the lower keeper members from their locked to their unlocked positions so the doors can open from the inside and cargo can be inadvertently discharged from the open door. The lowermost latch and keeper members are primarily subjected to such forces tending to open the doors since in general the force on the inside of the door is within three feet of the floor of the trailer van.

It is an object of the present invention to provide door lock apparatus making possible as many as desired of the above desirable features and overcoming as many as desired of the above problems. Another object is the provision of a door lock apparatus embodying, at at least two operable edges of a door, a latch member actuable to and from looking engagement with a keeper lock member, one of the lock members having first and second projecting members of which the first comprises a stem portion and a transverse portion and the other of which projecting members has a free end portion, the other of the lock members having two forks engaging the projecting members in straddling relation, essentially to prevent any movement of the door relative to the doorway. Another object is the provision of door-locking apparatus of the above type embodying means associated with the keeper member for retaining the keeper member within the latch member despite forces exerted on the door from the inside. A further object is the provision of such apparatus that can be made strong and can be manufactured at reasonable cost.

The above objects and advantages of the invention will be apparent from the following description of an embodiment of the invention, in conjunction with the accompanying drawings in which:

FIGURE 1 is a perspective view showing the rear end of a truck trailer van body, showing two door lock apparatuses embodying the invention;

FIGURE 2 is a perspective to a greatly enlarged scale showing the lowermost latch and keeper member of the lefthand door lock apparatus of FIGURE 1;

FIGURE 3 is an elevation viewed from the front of the apparatus of such lowermost lock and keeper member, showing the auxiliary securing member mounted on the latch member, the securing member being shown in its locking position in full lines, and in its released position in broken lines;

FIGURE 4 is a plan elevation, along line 44 of FIG- URE 3 and to the same scale; and

FIGURE 5 is a perspective of the keeper member of the apparatus to the same scale as FIGURE 2.

In the illustrated embodiment, reference numeral 1 designates the rear portion of a trailer truck body having a doorway opening 2 defined by lower and upper transverse members 3 and 4 and upright side members 5 and 6.

Doors

7 and 8 are mounted at the outer edges by hinges 9 so that they can open, and also close to an aligned coplanar relation.

Each of the doors has mounted on its outside rear face a door-locking apparatus 11 or 12 embodying the invention. Each apparatus 11 and 12 comprises a shaft 13 mounted on its door by upper and

lower mounting members

14 and 15 so it can rotate about a generally vertical axis A but cannot move vertically of the door. Each shaft 13 rigidly carries a handle 16 by which the shaft may be manually partially rotated about its axis A; each handle is adapted to be held in locking position by a known type of holding means 17 that comprises a base member 18 fixed to the door, an eye member 19 projecting through the handle 16 and adapted to receive the hasp of a padlock, and a latch member 20 that is rotatably mounted on base member 18 and acts to hold the handle in position and enables affixation of a conventional seal that must be broken before the door can be opened.

The upper mounting member 14 is made of two formed abutting sheet metal parts that are riveted or otherwise fixed to the upper outer surface of the door and are shaped to provide a tubular portion 22 rotatably supporting the upper end of shaft 13, and to provide a portion 23 that projects upwardly from the door to overlap the upper frame portion 4 to aid the lock apparatus in limiting movement of the door inwardly of the doorway. The lower mounting member 15 is generally similar in that it comprises two formed adjoining pieces of

sheet metal

24 and 25 fixed to the lower outer surface of the door and providing a tubular portion 26 into which the lower end of shaft 13 extends. This member 15 has a portion 27 that projects downwardly to overlap the lower frame member 3 and aid in limiting inward movement of the door in the doorway; it also has an opening 28 (FIGURES 2-4) through which projects the keeper member 29 of the lower portion of the lock apparatus; portion 27 of member 24 also partially overlaps a portion of the base of the keeper member at 30. Part 24 of this lower member 15 also has out-turned integral walls 31 to aid in stiffening the member 15 and particularly portion 27 thereof.

The keeper member 29 forming part of the lower portion of the lefthand lock apparatus of FIGURE 1 is shown in FIGURES 2-5. It is preferably formed of forged steel and comprises a base 32 that is fixed, as by welding, to the lower doorway frame member 3. Two fixed spaced

members

33 and 34 project forwardly to the base. Member 33 comprises a stem portion 35 preferably integral with base 32 and transverse portion 36 fixed to and preferably integral with stem portion 35. Stem portion 35 (FIGURE 3) is generally triangular in cross section with its apex extending toward the axis A of shaft 13. Projecting member 34, located on the other side of shaft axis A, through its length, except for its tapered free end 37 has a generally uniform triangular cross section preferably identical with the cross section of stem portion 35. The apex of its cross-sectional contour extends toward axis A and is spaced the same distance as the apex of stem portion 35; both triangular cross-sectioned parts are also spaced equidistantly to a plane normal to axis A. The portion of opening 28 in portion 30 of part 24 through which member 34 is adapted to project is shaped to fit closely to but clear the member 34. Keeper member 29 also has a hookshaped notch 38 formed in its projecting member 34, the notch extending transversely outward from the apex or inner edge of its member 34 and also extending toward the front or free end of member 34, to define a hook portion 39 that extends rearwardly toward base 32.

FIGURES 2-5 also show latch member 40 rigidly mounted on the lower end of shaft 13 of the lefthand lock apparatus of FIGURE 1. This latch member, preferably formed of forged steel, includes a central body portion 41 having a reduced diameter portion 42 that extends into and is fixed in the lower end of shaft 13, which is tubular at least in its end portions, and a transverselyextending lug 43 that bears against the lower end of tubular portion 26 to limit upward movement of the shaft and its keeper member. Integral with body portion 41 are two

forks

44 and 45 that are oppositely-extending and of opposite hand but otherwise of the same shape and dimension for ease in manufacture and for utilization in right and lefthand lock apparatuses. Each fork comprises two spaced

fingers

46 and 47 defining between them a tapered slot 48 adapted to fit closely but clear the triangular crosssectioned portions of the associated projecting

portions

33 and 34. Moreover, the front-facing surfaces 49 of the fingers are curved to provide cam surfaces that on fork 44 can wedgingly engage a curved rear-facing camming surface 50 of transverse member 36 of member 33 when the keeper is in locking position.

The rear surfaces and ends of the fingers are also so shaped that when the shaft 13 of the apparatus or FIGURES 2-4 is turned counterclockwise in FIGURE 4 to unlock the door, curved surfaces 51 of the fork 44 contact the front wall 52 of the base 32 of the keeper. thus forcing the shaft 13 and the door on which it is mounted away from the closed position of the door to initiate door opening. Continued turning of the shaft moves the fork 44 out from the space between transverse member 36 and the base 32 of the keeper member and permits the door to be fully opened; the curved ends 53 facilitate this. The shapes of the fingers also facilitate moving the keeper to its locking position.

Lower latch member 40 also has a manually-operable securing member or auxiliary latch 54 that is pivotally mounted about an axis B on a stud 55 fixed on the front portion of the latch member. This securing member. which preferably is formed of heavy sheet metal, has a forward-facing flange 56 that is circular about the axis B, and a forwardly-facing handle portion 57 by which member 54 can be manually moved. The member 54 is about axis B that is off-center of the latch member 40 and inclined to the keeper member so that when the latch member 40 is fully in its locked position in keeper member 29 (FIGURE 4), securing member 54 can be manually turned downwardly about its axis B so its flange 56 engages the notch 38 of projecting member 34 behind its hook portion 39 and thus secures latch member 40 against twisting or turning movement about its axis A. Downward movement of member 54 is limited by its contact with left hand (FIGURE 2) lug 59 on latch member 40. Securing member 54 tends to be held in this locking position by gravity biasing.

Securing member 54 can be pivotally turned upwardly, i.e., clockwise in FIGURE 3, to a released position. shown in broken lines in FIGURE 3, in which the flange 56 of the member 54 is completely removed from notch 38 of the keeper member, and in which lug 58 on securing member 54 contacts left hand stop 59 of the latch member. Member 54 remains in such position by gravity biasing since the center of gravity of member 54 is to the side of the vertical. When the securing member is in such released position, the latch member can then be rotated about the axis A to unlock the door as indicated above.

The keeper member 29 of the righthand lock apparatus in FIGURE 1 can be identical with the above described keeper member 29 of the lefthand apparatus, except that it is installed so its projecting

members

33 and 34 are of opposite hand from those of the keeper member of the lefthand apparatus shown in FIGURES 2-5. The latch member of the righthand lock apparatus also is identical with the latch member 40 of FIGURES 25. except that its securing member 54, suitably modified, is mounted for use offcenter on the opposite side of the shaft axis to engage the notch of the righthand lower keeper member 29.

The keeper members 2911, and latch members 40a at the upper door edges can be identical with those of the lower edges of the corresponding door and also include securing members 54. However, since the forces from loads inside the trailer are usually directed against the lower portions of the doors, in most cases it is not neces sary to utilize securing members 54 on the upper latch members and it is not necessary to provide the upper keeper members with the notches 38 as in the lower keeper members, although no harm is done if for standardization the upper keeper members have such notches. The upper keeper members and upper latch members, for standardization purposes, can otherwise be identical to the lower keeper members and latch members.

The apparatus can be operated as follows. Assuming that the doors are in their locked positions as shown in FIGURE 1, and it is desired first to open the lefthand door 7, the securing member 54 on the lefthand lower keeper member 29 is then moved to its release position, shown in broken lines in FIGURE 3; if any such securing member is on the upper keeper member it also is moved to its release position. Any seal that may be on the handle 13 is then broken, any lock locking the handle unlocked, and pivoted member 2'3 of holding means 17 is then moved to its release position. The handle then is pulled away from the door to turn the shaft 13 counterclockwise, as shown in the lefthand lock mechanism in FIGURE 1. This causes the rear curved surfaces 51 of the forks 44 of both the lower and upper latch members 40 and 40a substantially simultaneously to engage the front surfaces 52 of the lower and upper keeper members, thus driving the shaft 13 supporting these latch members and the door 7 on which the shaft is pivotally mounted away from the doorway members 3 and 4. The door is thus partially opened. Continued turning of the handle in the counterclockwise direction removes the forks 44 of these latch members from the space between the transverse members 36 and the base 32 of the lower and upper keeper members 29 and 29a, and causes the forks 45 of the same latch members to pass forwardly over the free ends of projections 34 of the keeper members, thus permitting the door to be completely released and to be swung completely open.

The righthand door can be similarly opened, the parts being so designed that clockwise movement of the handle, as shown on the righthand shaft 13 in FIGURE 1, will open the door.

When it is desired to close the lefthand door, the door can be partially closed with its handle 16 in the extreme open position until the curved outer edges 53 of the forks 44 of the lower and upper latch members contact the front surfaces 52 of the base members of the upper and lower keeper members. The close fit of the portion of openings 28 in part 24 adjacent the projecting members 34 aids in guiding the door and the latch members into proper alignment with the parts with which they are to cooperate. The handle is then moved in a counterclockwise direction to cause forks 45 of the latch members 40 and 40a to pass rearwardly over the free ends of the projections 34 of keeper members 29 and 29a and to turn the ends of the fingers of the forks 44 of these latch members into the spaces between the transverse members 36 of the projecting members 33 of the keeper members and the base members 32 of the keeper members sufficiently to cause the front surfaces 49 of the fingers of the forks 44 to contact the rear surfaces 50 of the transverse members 36. These surfaces act as camming surfaces and cooperate to provide wedging action that drives the door firmly inward at its upper and lower ends; this wedging action not only firmly holds the door in place, but also is particularly beneficial when, as shown in FIGURE 2, there is a resilient or compressible sealing gasket 61 at the edge of the door as is common in refrigerator type trailers.

The procedure is similar to close the righthand door in FIGURE 1.

The securing members 54 then are moved to their locked positions. The handles 16 are then secured in their door-locking positions, locks and seals being applied if desired.

The door lock mechanism described thus firmly holds each closed door at its upper and lower edges in the doorway opening. This prevents racking action that would otherwise tend to occur since the closed doors act as stiffeners against transverse movement of the top of the rear portion of the trailer relative to its bottom portion if the trailer is standing on uneven ground or is traveling over rough terrain. Furthermore, the two forks extending over two closely fitting projections on the keepers, and the securing members 54 on each of the lower keeper members, firmly hold the latch members in locked position, resist racking action, and also resist tendencies of the locking apparatus to open if substantial or abrupt forces are exerted on the door from the inside, as by shifting of loads in services in which high accelerations or decelerations are encountered.

It is apparent from FIGURE 4 that in the absence of these features a force exerted on the inside of the door would tend to cause a substantial force to be exerted between the front surface 49 of the fork 44 of the latch member and the rear surface 50 of the transverse member 36 of the keeper member, which would tend to drive the fork 44 inwardly and the other fork 45 of the keeper member outwardly, thus exerting a twisting action on the latch member and the shaft that could distort or break the latch member or shaft or break the connection between the latch member and the shaft. However, the securing member 54- when locked prevents outward movement of the fork 45 relative to the projecting member 34 of the keeper member, and thus resists any twisting action about the shaft axis, while the close fit f both forks about the projecting members of the keeper member prevents any twisting action transverse of the shaft axis.

Consequently, the improved lock apparatus of the invention enables the doors effectively to resist racking action, and holds the doors closed against forces and shocks from shifting loads inside the trailer exerted against the insides of the doors without the necessity of expensive expedients such as blocking dunnage adjacent the doors.

It is apparent that various modifications may be made in the illustrated embodiment without departing from the spirit of the invention.

What is claimed is:

1. In door securing apparatus for use with a door and an associated doorframe, means adapted for mounting on said door including a rotatable shaft and actuating means effective to rotate said shaft in either direction; a keeper member adapted for mounting on said door-frame; and a latch member actuatable to and form door securing engagement with said keeper member by rotation of said shaft, one of said members comprising first and second spaced projecting portions of which the first of said projecting portions comprises a stem portion and a transverse portion connected to said stern portion in transverse relation thereto and the second of said projecting portions as a free end portion, and the other of said members comprising two forks one of which forks is engageable beneath said transverse portion of said first projecting portion in straddling relation to said stem portion and the other of which forks can receive in stradding relation said second projecting portion, which second projecting portion is shaped to permit said other fork to pass over the free end of said projecting portion.

2. The apparatus of claim 1 in which said keeper member has said first and second projecting portions and in which said latch member has said two forks.

3. The apparatus of claim 1 comprising auxiliary'securing means operating between the one of said members having said forks and said second projecting portion of said other member to prevent relative movement of said keeper member and said latch member out of securing engagement.

4. The apparatus of claim 2 in which said latch member carries an auxiliary securing member movable there on from a released position to a securing position in which it engages said second projecting portion on said keeper member to prevent movement of said latch member relative to said keeper member from a securing positron to a released position.

5. The apparatus of claim 1 in which the surface of said transverse portion of said first projecting portion facing said stem portion and the surface of said fork adapted to engage said transverse portion are shaped so that when said members are engaged in securing relation said surfaces cause wedging relation between said mem bers carrying said first projecting portion and said fork.

6. The apparatus of claim 1 in which the surface of said transverse portion of said first projecting portion facing said stem portion is convexly curved and the surface of said fork adapted to engage said transverse portion is concavely curved, said curvatures being such when said members are engaged in looking relation said surfaces cause wedging relation between said members carrying said first projecting portion and said fork.

7. The apparatus of claim 2 in which the surface of said transverse portion of said first projecting portion facing said stern portion on said keeper member and the surface of said fork on said latch member are shaped so that when said members are engaged in securing relation said surfaces cause wedging relation between said members.

8. The apparatus of claim 2 in which the surface of sald transverse portion of said first projecting portion facing said stern portion on said keeper member is convexly curved and the surface of said fork on said member adapted to engage said transverse portion is concavely curved, said curvatures being such that when said members are engaged in securing relation said surfaces cause wedging relation between said members.

9. The apparatus of claim 3 in which said auxiliary securing means is mounted for movement from a released position to a securing position in which it prevents relative movement between said keeper member and said latch member out of securing engagement, and in which said auxiliary securing means is gravity biased to remain in securing position after it has been moved to such position.

10. The apparatus of claim 9 in which said auxiliary securing means is gravity biased to remain in released position after it has been moved to such position.

11. In door securing apparatus for use with a door and an associated door frame, means adapted for mounting on said door including a rotatable shaft and actuating means effective to rotate said shaft in either direction; a keeper member adapted for mounting on said door frame; a latch member actuatable to and from door securing engagement with said keeper member by rotation of said shaft, one of said members comprising a projecting portion having a free end, that comprises a shoulder spaced inwardly of and facing away from said free end, and the other of said members having a forked portion that is engageable with said projecting portion in straddling relation thereto when said latch member is in securing engagement with said keeper member, said forked portion being adapted to pass over the free end of said projecting member; and auxiliary securing means mounted on said memher having said forked portion and adapted to be engaged with the shoulder of said projecting portion for preventing relative movement between said latch member and said keeper member that would move said forked portion over said free end of said projecting member out of its securing engagement in straddling relation with said projecting portion.

12. The apparatus of claim 11 in which said keeper member has said projecting portion and in which said latch member has said forked portion.

13. The apparatus of claim 11 in which said auxiliary securing means is mounted on said forked portion for movement from a released position to said position where it engages said shoulder on said projecting portion having a free end to prevent relative movment between said keeper member and said latch member out of securing engagement, and in which said auxiliary securing means is biased to remain in securing position after it has been moved to such position.

14. The apparatus of claim 13 in which said auxiliary securing means is biased to remain in released position after it has been moved to such position.

15. The apparatus of claim 11 in which the surface of the said transverse portion of said projecting portion facing said stem portion and the surface of said forked portion adapted to engage said transverse portion are shaped so that when said members are engaged in securing relation said surfaces cause wedging relation between said members carrying said first projecting portion and said forked portion, and said securing means when connected holds said members engaged in wedging relation.

16. The apparatus of claim 12 in which the surface of said transverse portion of said first projecting portion facing said stem portion on said keeper member and the surface of said forked portion on said latch member are shaped so that when said members are engaged in securing relation said surfaces cause wedging relation between said members, and said auxiliary securing means when connected holds said lock members engaged in wedging relation.

17. The apparatus of claim 12 in which the surface of said transverse portion of said projecting portion facing said stem portion on said keeper member is convexly curved and the surface of said forked portion on said latch member adapted to engage said transverse member is concavely curved, said curvatures being such that when said members are engaged in securing relation said surfaces cause wedging relation between said members, and said auxiliary securing means when connected holds said members engaged in wedging relation.

18. The apparatus of claim 1 comprising auxiliary securing means operating between said member having said fork and said member having said projecting members, to prevent relative movement of said keeper member and the latch member out of securing engagement.

19. The apparatus of claim 2 comprising auxiliary securing means operating between a fork on said latch member and a projection on said keeper member to prevent relative movement of said keeper member and said latch member out of securing engagement.

20. The apparatus of claim 2 comprising an auxiliary securing member movably mounted on said latch member and adapted to engage said second projecting portion on said latch member to prevent said first mentioned fork from moving out from its securing engagement beneath said transverse portion of said first projecting portion of said keeper member, said auxiliary securing member being biased to remain in engagement with said second projecting portion.

21. The apparatus of claim 11 in which said latch member is mounted on said shaft and comprises said forked portion extending laterally in one direction from the axis of said shaft and a second portion extending laterally in a generally opposite direction from said shaft axis; and in which said keeper member is mounted on said door frame and comprises said first mentioned projecting portion that is straddled by said forked portion during securing engagement and a second projecting portion having a shoulder facing generally toward the door and adapted to be engaged by said second laterally extending portion of said latch member when said latch member engages said keeper member in securing engagement, whereby when said auxiliary seen-ring means engages the shoulder of said first mentioned projecting portion of said keeper member, said laterally extending portion of said latch memher is secured in engagement with said shoulder of said second projecting portion of said keeper member.

22. The apparatus of claim 21 in which said auxiliary securing means is mounted on said forked portion of said latch member for movement from a released position to a securing position in which it prevents relative movement between said keeper member and said latch member out of securing engagement, and in which said auxiliary securing means is biased to remain in securing position after it has been moved to such position.

23. The apparatus of claim 22 in which said auxiliary securing means is biased to remain in released position after it has been moved to such position.

24. The apparatus of claim 21 in which said second projecting portion of said keeper member comprises a stem portion and a transverse portion connected to said stem portion in transverse relation thereto and embodying said shoulder facing said door, and in which said second projecting portion of said keeper member is fork-shaped and engages said stem portion in straddling relation.

25. The apparatus of claim 11 in which said projecting portion having said free end has a slot therein embodying said shoulder, and in which said securing means has an edge portion adapted to fit in said slot and engage said shoulder when said securing means is engaged with said projecting portion.

26. The apparatus of claim 21 in which said first mentioned projecting portion having said free end has a slot therein embodying said shoulder facing away from said free end, and in which said securing means has an edge portion thereof adapted to fit in said slot and engage said shoulder when said securing means is engaged with said projecting portion.

References Cited UNITED STATES PATENTS 2,753,205 7/1956 Forssell 29234l.15 2,753,206 7/1956 Forssell 292341.17 2,753,207 7/1956 Forssell 292341.17 2,764,443 9/1956 Bennett 292-210 X 2,861,830 11/1958 Bennett 292218 X 3,099,473 7/1963 Pastva 292-218 X 1,204,667 11/1916 King 292210 MARVIN A. CHAMPION, Primary Examiner 20 R. L. WOLFE, Assistant Examiner US. Cl. X.R. 292-54, 210