Title:
LATCH MECHANISM
United States Patent 3806174


Abstract:
A latch mechanism for latching a movable body structure, such as a tilting truck cab, to a fixed body structure, such as a truck chassis, including a rotatably-mounted spring biased hook which is held in a locking position by an over-center locking mechanism, and may be rotated out of a locking position by actuation of a lever connected thereto.



Inventors:
HERMAN D
Application Number:
05/213324
Publication Date:
04/23/1974
Filing Date:
12/29/1971
Assignee:
INT HARVESTER CO,US
Primary Class:
Other Classes:
292/DIG.49
International Classes:
E05C19/14; (IPC1-7): E05C5/02
Field of Search:
292/66,113,247,DIG
View Patent Images:
US Patent References:
3352585Door lock with safety device1967-11-14Crosswell et al.
3041097Sliding door latch1962-06-26Eads
3019043Sliding door lock1962-01-30Woodworth et al.
2800346Hand actuated toggle1957-07-23Manning



Foreign References:
DE646680C
SE93597C
Primary Examiner:
Moore, Richard E.
Attorney, Agent or Firm:
Krubel, Frederick Harman Floyd J. B.
Claims:
I claim

1. In a latch mechanism for latching a movable vehicle body structure to a stationary body structure, the combination comprising: support means for pivotally supporting thereon actuating lever means, said support means being adapted to be secured to one of said body structures;

2. In a latch mechanism for latching a movable vehicle body structure to a stationary body structure, the combination comprising:

3. In a latch mechanism for latching a movable vehicle body structure to a stationary body structure, the combination comprising:

4. In a latch mechanism for latching a movable vehicle body structure to a stationary vehicle body structure, the combination comprising:

5. In a latch mechanism as set forth in claim 4, wherein the pivotal axis of said second pivot pin lies on one side of a plane containing the pivoted axis of said first pivot pin and said latch pin when said latch hook is in its latched position and on the opposite side of said plane when said latch hook is in its unlatched position.

Description:
This invention relates generally to latch mechanisms, and more particularly to a latch mechanism for securing a sill of a tilting truck cab to the fixed truck frame assembly.

In the past, numerous latch mechanisms have been developed which have suffered from a variety of deficiencies such as being complicated in structure, having an excessive number of parts and in some instances being difficult to manufacture. Accordingly, it is a purpose of this invention to provide an uncomplicated latch mechanism comprising a minimum number of parts, which parts are easy to manufacture and assemble.

SUMMARY OF THE INVENTION

Briefly summarized, the latch mechanism, herein, comprises a hook which is biased into a latching position by a spring means. The hook is pivotally attached to a lever member and the lever member, in turn, is pivotally mounted on one of the two elements that are to be latched together. The device is constructed to include an over-center locking feature. Actuation of the lever means is effective to move the hook against the tension of the associated spring means to an unlatched position, and release of the actuating lever permits the hook to move back to a latching position.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a part of a truck cab and frame assembly secured together by a latch mechanism of the present invention;

FIG. 2 is a front view in elevation of the latch mechanism of FIG. 1;

FIG. 3 is a view of the latch mechanism taken along line 3--3 FIG. 2 showing the mechanism in a latched position;

FIG. 4 is a view of the latch mechanism in a partially unlatched or safety position;

FIG. 5 is a view of the latch mechanism in an unlatched position;

FIG. 6 is a side view of the latch mechanism, after unlatching, showing the truck cab completely separated from the frame assembly;

FIG. 7 is a side view of the latch mechanism in the process of re-engagement.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to the drawings wherein like reference characters refer to similar parts, 10 refers generally to the latch mechanism embodying the invention. In FIG. 1, the latch mechanism 10 is shown as latching together, a movable part of the truck body, namely a tilting truck cab 11 to a nonmovable part of the truck, namely, a frame assembly 12 of the truck.

The latch mechanism 10 includes a first support means 13 for supporting a latching hook member and an actuating lever means for controlling motion of the hook. The support means 13 is shown in FIG. 1 as being mounted on a wall section 14 of the tilting truck cab 11. The latch mechanism 10 also includes a second support means 15 secured to the truck frame assembly 12 for supporting a latch pin.

As shown in FIG. 1 of the illustrated embodiment, the first support means 13, which is in the form of a box-like structure means, is secured by suitable means such as by welding to the wall section 14 of the tilting truck cab 11. The second support means 15 is attached to the nonmovable part of the truck, namely a frame member 16 of the frame assembly 12.

The first support means 13 comprises a pair of parallel flanges 17 and 18, and a hinge pin 20 journalled in the two flanges 17 and 18. A stop member 19 extends between and is attached to the flanges 17 and 18. The actuating lever means 21 comprises a pair of symmetrical straps 22 and 23, the lower ends of which are offset and are journalled on the hinge pin 20. The symmetrical straps 22 and 23 are disposed in parallel arrangement. At about midway the length of the lever actuating means, a pin 24 extends through the straps 22 and 23. The pin 24 pivotally supports the upper end of a hook member 25. An actuating handle in the form of a pin 26 extends through the upper ends of the straps 22 and 23.

The hook member 25 is an elongated flat plate-like member which is pivotally supported on the pin 24 and is disposed between the symmetrical straps 22 and 23 forming the actuating lever 21. The hook 25 extends downwardly and is formed with a notch 27 which is adapted to engage a latch pin. The hook also is formed with a curved slot or aperture 30 which receives therethrough the hinge pin 20. During movement of the hook between latched and unlatched positions the hook by virtue of this slot arrangement, is free to translate about the hinge pin 20 when the lever 21 is actuated. The slot 30 is of a predetermined length so that at a particular point during rotation of the lever 21, the hook 25 will begin to rotate with the lever 21.

The second supporting means 15 may comprise a pair of right angle flange members 31 and 32, secured to the frame member 16. These flange members support a horizontally extending latch pin 33 which is positioned to engage the notch 27 of the hook 25.

A tension spring 34 has one end secured to the hook 25 and the other end to a part of the truck.

FIG. 3 illustrates the latched position in which the components above and below a parting line 35, are firmly clamped together by action of the hook 25 on pin 33. The actuating lever means 21 is shown in FIG. 3 as displaced from a line 36 which passes through the center of pins 20 and 33 by an angle θ. The spacing between pins 24 and 33 is chosen such that the hook 25 is subjected to tension at this position. If the actuating lever 21 is rotated counterclockwise through the angle θ so that the centers of pins 24, 20 and 33 are coincident on line 36, the distance between pins 24 and 33 increases, placing greater tension on the hook. In this over-center mechanism the force required to pass the linkage through this point of increased tension is a deterrent to unintentional release of the latch, i.e., release can only be attained by application of an external force on the actuating lever 21 through the handle 26.

The process of releasing the latch is shown in FIGS. 4, 5 and 6. The release function is initiated by application of a force toward the left (See FIGS. 3 and 4) on handle 26, which is of sufficient magnitude to rotate the actuating lever 21 counterclockwise through the "center" position described above and on to the position shown in FIG. 4. At that point the distance between pins 24 and 33 has decreased markedly, lowering the hook 25 to the extent that it is freed from the latch pin 33. This position is referred to as the "safety position."

Continued counterclockwise rotation of the actuating lever 21 causes the right end of the hook slot 30 to contact the hinge pin 20. When this occurs the actuating lever 21 and the hook 25 rotate coincidentally around hinge pin 20 and the hook ceases to lower and swings out of alignment with the latch pin 33 as shown in FIG. 5. This position permits separation of the components above and below the parting line 35, i.e., the cab may be tilted upwardly as indicated by the arrow in FIG. 5.

Force exerted on the hook by extension of the spring 34 is sufficient to require the operator to hold the control mechanism attached to handle 26 in the released position. When the cab is tilted, with the hook separated from the latch pin, release of the control handle 26 by the operator permits the spring to pull the hook back to a vertical position at rest against the stop member 19 as seen in FIG. 6.

As the cab is lowered the cam surface 37 at the bottom of the hook 25 contacts the latch pin 33 forcing the hook aside, extending the spring, until a point is reached where the hook notch 27 may be pulled into engagement with the latch pin. At this time the assembly has assumed the safety position of FIG. 4. This occurs automatically as the cab is lowered with no action required on the part of the operator. In the safety position the components above and below the parting line 35 are not clamped tightly together, however, the degree of separation is limited. Separation will cause the latch pin to pull downward on the hook, rotating the actuating lever counterclockwise until the right end of the hook slot 30 contacts the hinge pin 20. Further separation is blocked by action of the hook on pin 33. The net result is that in the safety position the cab is not tightly secured as required for proper vehicle operation, but neither can it tilt more than a few degrees before being restrained by the latch.

The latched position is attained from the safety position simply by rotating the actuating lever 21 clockwise through the "center" position to that shown in FIG. 3. The latch is then in locked engagement.

It will be apparent from the foregoing that I have advantageously provided a latching mechanism which is of simple construction and includes a minimum number of parts, is easy to manufacture and yet is an effective mechanism.

While a preferred embodiment of the invention has been specifically disclosed, it is to be understood that the invention is not limited thereto as other variations will be apparent to those skilled in the art and the invention is to be given its fullest possible interpretation within the terms of the following claims.