US2894777A - Preload latch - Google Patents

Description

J. E. HOGAN PRELOAD LATCH July 14, 1959 2 Sheets-Sheet 1 Filed Dec. 3, 1956 jiu' w INVENTOR. JOHN 5/1064 grroe/vsrs J. E. HOGAN PRELOAD LATCH July 14, 1959 2 Sheets-Sheet 2 Filed Dec. s, 1956 INVENTOR.

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do/r/v 5/7004 oil-I a ATTae/ws'rs United States Patent PRELOAD LATCH John E. Hogan, Los Angeles, Calif., assignor to Clark Hartwell, Los Angeles, Calif., doing business under the fictitious name and style of Hartwell Aviation Supply Company Application December 3, 1956, Serial No. 626,030

7 Claims. (Cl. 292-113) This invention relates to preload latches, that is, to latches arranged to draw cooperating structures together with a predetermined initial load so as to eliminate relative movement of the structures under intended conditions of operation.

Included in the objects of this invention are:

First, to provide a preload latch which is particularly arranged for effecting end-to-end connection of component structures, and may be arranged for use in sets to join, for example, an instrument carrying no se-piece to the fuselage of an aircraft.

Second, to provide a preload latch wherein latch arms projecting from one structure may be readily guided into engagement with a mating catch element in the component structure, whereupon the two structures may be drawn together and secured.

Third, to provide in a preload latch a novel means for controlling the movement of the catch element so as to move the catch element between an inoperative position free from interference with the mating latch, and an operative position holding the latch with predetermined tension.

' Fourth, to provide in a preload latch a novel, yieldably -mounted, latch element and means for guiding the latch element into proper catch-engaging position.

Fifth, to provide a preload latch which is provided with a manually operable handle adapted to be folded into a position flush with the surrounding structure in which the latch is mounted.

With the above :and other objects in view, as may appear hereinafter, reference is directed to the accompanying drawings in which:

Figure l is a top or plan view of preload latch, show ing the components thereof in their connected or latched position;

. Fig. 2 is a side view thereof, indicating fragmentarily by dotted lines the latch and latch hook;

Fig. 3 is an end view of one component of the latch which carries the latch hook and operating mechanism;

- Fig. 4 is a separated-view of the latch components with the latch shown in itsopen position;

I Fig. 5 is an enlarged longitudinal sectional view taken through 5-5 of Fig. l;

Fig.' 6 is a fragmentary, partial elevational, partial longitudinal, sectional .vieW, similar to Fig. 5 but showing the parts of the latch structure in its open position;

Fig.7 is a sectional view through 77 of Fig. 5, showing the parts of the latch in its closed position.

' The preload latch includes a housing member 1 having a central channel portion 2 of rectangular cross section to form verticalside walls .3 and a bottom wall 4. The upper edges of the side walls are provided with laterally extending flanges 5 which are contoured so that the upper. side of the housing member 1 may be mounted flush in a surrounding structure, for example, an airplane fuselage, wing, or appendage.

" The ends of the channel portion 2 are closed. One

end is closed by an apron 6 which projects beyond the boundaries of the channel portion 2 and is adapted for flush mounting in the end of the structure in which the housing 1 is mounted. The apron is provided with a centering aperture 7 communicating with the channel 2. The centering aperture is provided with tapering side walls.

Mounted within the channel 2 is a latch hook or catch member 8 having a hook end 9. The catch member is suspended within the channel 2 by means of forward suspension arms 10 connected to the catch member 3 by a shaft 11. The suspension arms 10 are also provided with journal pins 12 which extend laterally through journal bosses provided in the side walls 3 of the channel 2.

The catch member 8 extends rearwardly of the suspension arms 10 and is joined to a rearward suspension arm 13 by means of a journal pin 14. The'suspension arm 13 is j-ournaled relative to the housing 1 on a shaft 15 which extends through the side walls 3 and is provided with bushings 16 for centering the suspension arm 13 in the channel 2. p

The pivotal connections of the forward suspension arms 10 and rearward suspension arm 13 with the side Walls 3 are located above their'pivotal connections with the catch member 8. Furthermore, the suspension arm 13 is longer than the suspension arms 10; consequently, the hook member is capable of a forward and rearward movement which also results in upward displacement of the hook end 9 as the catch member 8 moves forward. This movement is utilized to move the hook end 9 of the catch member 8 free of the mating latch member, as Will be described hereinafter.

Also mounted on the shaft 11 are connecting bars 17 which extend forwardly and are connected by journal pins 18 to a U-shaped yoke lever 19 located'near the forward extremity of the housing 1, that is, adjacent and above the centering aperture 7. The legs of the yoke lever 19 are located contiguous to the side walls 3 and are journaled at their forward extremities on a. transverse journal shaft 20 carried by the side walls 3'.

The open upper side of the channel12 is adapted to be covered by a handle 21 shaped to conform to the surrounding structure in which the housing is mounted. The forward end of the handle 21 is provided with ears 22 which extend into the channel 2 and are provided with slots 23 to receive the journal shaft 20. The handle is intended to effect pivotal movement of the yoke lever 19, consequently, the ears 22 are provided with notches 24 which engage the ends of a pin 25 at the sides of the lever 19.

The ends of the pin 25 are out of engagement with the notches 24 when the handle is in its closed position and the slots 23 are raised relative to the journal shaft 20. When the handle is raised, the ears 22 are guided by the slots 23 so as to direct the notches 24 into engagement with the pins 25 thereby, on further pivotal movement of the handle 21, the yoke lever 19 may be pivoted from the position shown in Fig. 5 to the position shown in Fig. 6, and in so doing moves the catch member 8 between its extreme positions. I i

It is desirable that the mechanism within the housing be immobilized when the handle 21 is in its closed position, such as shown in Fig. 5. This is accomplished by means of pairs of stops 26 formed by the ears 22 immediately beyond the slots 23. The stops 26 prevent upward movement of the yoke lever 19 when the handle is in its closed position. To prevent downward move ment, a pair of set screws 27 mounted in bos'ses28 extend upwardly from the bottom wall 4 of the channel'2. These serve to limit downward pivotal movementofithe 'yoke lever 19.

2,s94,777 V l The locations of the stops 26 and set screws 27 are such as to locate the axis of the pin 18 slightly below a plane passing through the axes of pins 11 and 20. This is an overcenter position so that tension applied to the hook 8 tends to turn the yoke lever 19 counterclockwise abotu the pin 20, as viewed in Fig. l, so that no upward thrust is applied to the handle lever 21.

The stops 26 may be omitted or relieved to clear the pin 25. This permits the set screws to be adjusted so as to predetermine accurately the overcenter position of the pin 18.

The extremity of the handle 21 may be secured in its closed position by any suitable fastening element, for example, a pin fastener 29 may be journaled in the handle member and an aperture provided in a perforated bracket 30 secured within the channel 2. The margins of the aperture may be key-slotted to interlock with the pin in a conventional manner.

A spring 31 is interposed between the yoke lever 19 and handle 21 for the purpose of lifting the handle to a manually accessible position when the fastening means is disconnected.

The structure thus far described occupies one component of the preload latch. The other component includes a body member 32 which may take various forms, depending on the structure in which it is to be mounted. In the drawings the body member 32 is shown as including a top wall 33 which may be flush with or submerged below the surface of the structure in which it is mounted. An end wall 34 may conform to the end of such structure intended to confront the structure in which the housing 1 is mounted. The side flanges 35 connect the top and end walls.

Formed on the outside of the end wall 34 is a centering boss 36 tapered to mate with the centering aperture 7, as shown best in Fig. 5. The centering boss 36 is provided with a clearance bore 37 and is intersected by a transverse bore 38. Oscillatably mounted in the trans verse bore 38 is an anchor bar 39 which is transversely screw-threaded to receive a screw shaft 46 which projects rearwardly from the centering boss 36 to form a latch bar 41. The rearward extremity of the latch bar is bifurcated and equipped with a transversely disposed latch pin 42 dimensioned to be engaged by the hook end 9 of the catch member 8.

The end of the screw-threaded shaft 40 within the body member 32 is provided with opposed fiat sides 43. Mounted within the body member is a leaf spring 44 so disposed as to engage the fiat sides 43, so that the shaft 4% and latch bar 41 tend to maintain a position in which one of the flat sides is engaged. The flat sides 43 are oriented with respect to the latch pin 42 so that the latch pin may be readily maintained in proper orientation relative to the hook end 9. The spring 44 also maintains the directional position of the latch member to allow for centering with the aperture when in the withdrawn position.

Operation of the preload latch is as follows:

Several of the latches are commonly used for the connection of two structures, for example, a nose-piece which is to be attached to the forward end of a fuselage. In such installation, the housing 1 of each latch is mounted and secured in the forward end of the fuselage with its upper surface flush with the surface of the fuselage and the end wall or apron 6 flush with the end of the fuselage. Due to the streamlined contour of the fuselage, the apron or end wall 6 is not at right angles to the outer surface of the housing, but instead forms an obtuse angle.

Correspondingly, the end wall 34 of the body member 32 forms an acute angle with the top wall 33 so that the end Wall 34 is parallel to the apron 6 when the nose piece of the aircraft is brought into confronting relation with the end of the fuselage. The centering apertures '7 and the centering bosses 36 are so located that when in mating relation the fuselage and nose-piece are in proper relative position,

The latch bars 41 of the several preload latches are capable of limited pivotal movement so that in bringing the nose-piece into position relative to the fuselage they may be readily guided through the apertures 7 into the channels 2. To facilitate further guidance of each latch bar 41 into engagement with its catch member 8, the bottom wall of each housing 1 may be provided with a cam boss 45, as shown in Figs. 5 and 6.

In the course of mounting the nose-piece on the fuselage, the handle 21 of each housing 1 is in its raised position, such as shown in Figs. 4 and 6. In this position the hook end 9 of each catch member 8 is in an elevated position, permitting free entrance of the corresponding latch bar 41. After the nose-piece has been brought approximately into position and the centering bosses 36 have been aligned with the centering apertures 7, the handle of each preload latch may be moved to its closed position. in doing so, each hook end 9 moves in an arc passing through the corresponding latch pin 42, so as to engage the latch pin 42 and draw the latch bar 41 into the channel 2 of the housing 1.

The amount of tension applied to the latch bar 41 depends upon the adjustment of the shaft 40. The adjustment is made in increments of half turns of the latch bar. It is desirable that the preload tension on the latch bar be sufficient to hold the component structures tightly together under the intended conditions of operation. The leverage afforded by the handle 21 and the linkage between the connecting bars and yoke lever 19 is such that a substantial preload tension may be applied to the latch bar 41 without requiring undue manual force to close the handle 21.

Inasmuch as any movement of the axis of the pin 18 past the plane defined by the axes of the pins 11 and 29 tends to reduce the preload tension between the components of the latch, the final position of the pin 18 may be critical. Adjustment of the set screws 27, permitting accurate location of the pin 18, provides a trim or fine adjustment of the preload tension.

While a particular embodiment of this invention has been shown and described, it is not 'mtended to limit the same to the exact details of the construction set forth, and it embraces such changes, modifications, and equivalents of the parts and their formation and arrangement as come within the purview of the appended claims.

What is claimed is:

1. A preload latch, comprising: a housing defining a channel and having an end Wall defining a centering aperture; a body member including a centering member adapted to enter said aperture and engage the walls thereof to dispose said housing and body member in predetermined alignment; a latch member universally mounted in said body member said centering member having a bore adapted to receive loosely said latch member thereby to permit limited uinversal displacement of said latch member, said latch member protruding beyond said centering member and guidable through said aperture into the channel of said housing; a catch element mounted in said housing; and means for moving said catch element into and out of engagement with said latch member.

2. A preload latch, comprising: a housing defining a channel and having an end wall defining a centering aperture; a body member including a centering member adapted to enter said aperture and engage the walls thereof to dispose said housing and body member in predetermined alignment; a latch member universally mounted in said body member said centering member having a bore adapted to receive loosely said latch member thereby to permit limited universal displacement of said latch member, said latch member protruding beyond said centering member and guidable through said aperture into the channel of said housing; a catch element mounted in said housing; and means for moving said catch ele ment between a laterally offset disengaged position relatively near said aperture and a latch-engaging position relatively remote from said aperture, said catch element, in moving from said near to said remote position, bemg engageable with said latch to draw said latch under tension into said housing, and said centering aperture and centering member into engagement.

3. A preload latch, comprising: a housing defining a channel and having an end wall defining a centering aperture; a body member including a centering member adapted to enter said aperture and engage the walls thereof to dispose said housing and body member in predetermined alignment; a latch member universally mounted in said body member said centering member having a bore adapted to receive loosely said latching member thereby to permit limited universal displacement of said latch member, said latch member protruding beyond said centering member and guidable through said aperture into the channel of said housing; yieldable means for biasing said latch member whereby said latch member tends to assume a predetermined position relative to said body member, said aperture being beveled to deflect said latch member therein; cam means in said housing channel to deflect said latch member into a catch engaging position as said housing and body member are brought together; a catch element mounted in said housing; means for moving said catch element between a laterally offset disengaged position relatively near said aperture and a latch-engaging position relatively remote from said aperture, said catch element, in moving from said near to said remote position, being engageable with said latch to draw said latch under tension into said housing, and said centering aperture and centering member into engagement; and means for adjusting the relative positions of said catch element and latch to vary the tension applied to said latch when said catch is in its remote position.

4. A preload latch, comprising: a housing defining a channel and having an end Wall defining a centering aperture; means for mounting said housing in a structure with the open side of said channel substantially flush with a side of said structure and said end wall substantially flush with an end of said structure; a body member including a centering member adapted to enter said aperture and engage the walls thereof to dispose said housing and body member in predetermined alignment; a latch member universally mounted in said body member said centering member having a bore adapted to receive loosely said latch member thereby to permit limited universal displacement of said latch member, said latch member protruding beyond said centering member and guidable through said aperture into the channel of said housing; a catch element mounted in said housing; a handle movable between a position closing said channel and an angular position; means suspending said catch element for movement between a latch-engaging and a latch-releasing position; and means interconnecting said catch element and handle.

5. A preload latch, comprising: a housing defining a channel and having an end wall defining a centering aperture; a body member including a centering member adapted to enter said aperture and engage the walls thereof to dispose said housing and body member in predetermined alignment; a latch member universally mounted in said body member said centering member having a bore adapted to receive loosely said latching member thereby to permit limited universal displacement of said latch member, said latch member protruding beyond said centering member and guidable through said aperture into the channel of said housing; yieldable means for biasing said latch member whereby said latch member tends to assume a predetermined position relative to said body member, said aperture being beveled to deflect said latch member therein; cam means in said housing channel to deflect said latch member into a catch engaging position as said housing and body member are brought together; a catch element mounted in said housing; and means for moving said catch element to and from said aperture and to pivot said catch element laterally in the region of its movement nearest said aperture to clear said latch member.

6. A preload latch, comprising: a housing defining a channel and having an end Wall defining a centering aperture; a body member including a centering member adapted to enter said aperture and engage the walls thereof to dispose said housing and body member in predetermined alignment; a latch member universally mounted in said body member said centering member having a bore adapted to receive loosely said latch member thereby to permit limited universal displacement of said latch member, said latch member protruding beyond said centering member and guidable through said aperture into the channel of said housing; a catch element mounted in said housing; means for moving said catch element to and from said aperture and to pivot said catch element laterally in the region of its movement nearest said aperture to clear said latch member; and means for adjusting the elfective length of said latch member to vary the tension load imposed thereon by said catch element.

7. A preload latch, comprising: a housing defining a channel and having an end wall defining a centering aperture; a body member including a centering member adapted to enter said aperture and engage the walls thereof to dispose said housing and body member in predetermined alignment; a latch member universally mounted in said body member said centering member having a bore adapted to receive loosely said latch member thereby to permit limited universal displacement of said latch member, said latch member protruding beyond said centering member and guidable through said aperture into the channel of said housing; a catch element mounted in said housing; link and lever means for moving said catch element to and from said aperture, said means exerting maximum leverage as said catch element is moved in the region remote from said aperture thereby to apply tension to said latch member, said means also being operative to move said catch element laterally of said latch member as said catch element is moved in the region nearest said aperture; and means for adjusting the effective length of said latch member to vary the tension load imposed thereon by said catch element.

References Cited in the file of this patent UNITED STATES PATENTS 2,710,214 Summers June 7, 1955 2,712,955 Andrews July 12, 1955

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