US2736599A - Drop hook - Google Patents

Description

ansaso like to engage and press against the outside of the jaw 18 at one or both points indicated at 18a and 18b. The pressure thus exerted at either one or both of these points will unlock the toggle linkage 33, 36 by forcing the pivot pin 35 over center from its jaw open position, as shown in Fig. 2. This will permit the operating arm 38 to be pulled down to a position for throwing the bell crank lever 33 upwardly due to the pressure exerted on the pivot pin 35. Such action will move arrn 33a and its pivot pin 32 downwardly, forcing the pivot pin 29 downwardly to allow the pivot pin 32 to go past center to its over center position between the pivot pins 30, 34. This will effect an over center toggle lock to the toggle connection between the bell crank 23 and load link 25 at 29. By giving the arm 38 a snap in this direction, the impact of the bell crank 2S on the jaw 18 at 21a will hold the over center locking link 31 and the leg 33a of the bell crank lever over center at 32, as shown in Fig. 1. In each over center position, they will resist any swinging movement of the jaw and lock it in its closed position under load (see Fig. l).

To release the load, the operatingl arm 38 is pulled away from the housing to swing laterally outward therefrom about its fulcrum at 41 which acts through the operating link 36 to rock the bell crank lever 33, 33a and break its over center locking position at 32 relative to the locking link 31. As the pivotal connection therebetween is thus swung over center, the linkage will collapse, permitting the bell crank 28 to be swung upwardly, carrying with it the load link which will thereupon free the holding lock on the jaw 18 and permit it to swing into its open or unloading position shown in Fig. 2. This action will be assisted, in order to overcome the pressure of the load on the load hook 19, by the slightly above center position of the pivot pin 29. As the jaw is released it will be snapped open by the weight of the load, the operating arm being limited'in its upward throw by the bumper 43 engaging that portion of the housing 44.

It may be noted that with the operating arm 38 in the position shown in Fig. 2, with the bumper 43 lying against the projection 44, the pivot pin 35 is below center relative to pivot pins 34 and 39. This serves to lock the operating arm 38 in this position and hold the jaw 18 open for reloading until it is engaged at the points 18a or 18b. Upon force being applied at these points, as above set forth, links 25 and 31 will swing the bell crank lever 33 to its position as shown in Fig. l, to throw the pivot pin 35 upwardly over center relative to pivot pins 34, 39. The lever 38 will then be freed to be pulled downwardly to its locking position, as shown in Fig. l`.

The invention claimed is:

l. A drop hook of the character described including a housing having a xed jaw, a swinging jaw fulcrumed on said housing with one end movable into and out of load supporting position relative to said fixed jaw, a load link having one end pivotally connected to the opposite end of said swinging jaw and normally seating on said jaw transversely thereof, a bell crank pivoted at one of its arms on said housing and pivotally connected intermediate its ends to the said opposite end of said load link, said pivots disposed in substantial alignment transversely to the direction of the load, said last-mentioned pivotal connection being slightly above center, a second bell crank lever fulcrumed intermediate its ends on said housing, a locking link pivotally connecting one arm of said last named lever to the opposite arm of said rst named bell crank lever, the pivotal connection between said locking link and last named lever lying over center with respect to the plane through the fulcrum of said lever and the pivotal connection between said link and crank, said plane extending in the general direction of the load at a slight angle thereto, an operating arm in the form of a third bell crank lever fulcrumed intermediate its ends upon said housing with a short leg pivotally linked to the opposite end of said second bell crank lever by an oper-- ating link whereby said jaw will be locked in load supporting position by the over center relation of said locking link and said second bell crank lever relative to said bell crank and load link, and be released from said locking position upon said second bell crank lever being swung by said operating arm to throw its said over center connection with said locking link to the opposite side of its center into collapsed position.

2. A drop hook of the character described including a housing having a xed jaw, a swinging jaw fulcrumed on said housing having one end movable into and out of load supporting position relative to said ixed jaw, the combination therewith of a releasable lock for holding said swinging jaw in load sustaining position comprising a pair of links pivoted end to end normally seating upon the opposite end of said swinging jaw transversely to the direction of the load, one of said links being pivotally connected at its opposite end to said jaw and the other said link being pivotally connected at its opposite end to said housing, the latter of said links having an angularly extending arm linked by an over center locking linkage to one leg of a bell crank lever pivoted intermediate its ends on said housing, and an L-shaped operating arm fulcrumed on said housing having linked connection with the other leg of said bell crank lever, said operating arm being movable to swing said bell crank lever in a direction to break said over center locking linkage and permit collapse of said first-mentioned links away from said swinging jaw to free it for outward swinging movement from said fixed jaw.

3. A drop hook of the character described including a housing having a tixed jaw, a swinging jaw fulcrumed on said housing with one end movable into and out of load supporting position with said fixed jaw, the combination therewith of a releasable lock for holding said swinging jaw in load sustaining position comprising a pair of links pivoted end to end and disposed in longitudinal alignment with one another transversely of said housing and in seating engagement with said movable jaw when the latter is in load sustaining position, one of said links being pivotally connected at its outer end to said jaw and the other said link being pivotally connected at its outer end to said housing, the housing pivoted link having an angularly extending arm linked to one leg of a bell crank lever fulcrumed intermediate its ends on said housing through a pivotally mounted over center locking linkage, and an operating L-shaped arm fulcrumed on said housing intermediate its end pivotally linked to the other leg of said bell crank lever, said operating arm being movable to swing said bell crank lever in a direction to throw its link connection over center to permit collapse of said 'first-mentioned links away from said swinging jaw for freeing said jaw for outward swinging movement from said fixed jaw, said swinging jaw having an arcuate bearing surface concentric with its point of fulcrum and a thrust bearing on said housing slidably engageable thereby during the swinging of said jaw to and from said fixed jaw.

- 4. A drop hook of the character described including a housing having a depending fixed jaw, a swinging jaw fulcrumed on said housing inwardly of its ends with its lower end movable into and out of load supporting position with said fixed jaw and having a laterally offset projection above and spaced from the fulcrum, toggle linkage in said housing pivotally connected with said extension and including a bell crank pivoted at one end to said housing and having an upstanding portion above said linkage,a second bell crank lever fulcrumed intermediate its ends on said housing above said first bell crank, an over center locking link connecting the upstanding portion of said first bell crank to one leg of said second bell crank to provide a locking linkage extending substantially in the direction of the load with an offset over center pivotal connection intermediate said link and said second bell crank lever, an operating handle fulcrumed intermediate its ends in said housing having a free load re- 5 leasing end, and a link connection between the other arm of said second bell crank and the free end of said operating lever for swinging said lever in a direction to throw said locking linkage over center from locking position to a collapsing position for releasing said swinging jaw.

5. In a drop hook, a housing, a fixed jaw secured to said housing, a swinging jaw pivoted inwardly of its ends in said housing with one end movable into and out of load supporting position with said fixed jaw, a load link pivoted at one of its ends to the opposite end of said swinging jaw, a bell crank pivoted at the end of one of its arms to said housing in parallel alignment with the pivot of said load link, a pivot connecting the end of said load link with the intermediate portion of said bell crank, a second bell crank pivoted intermediate its ends to said housing beyond the opposite end of said swinging jaw, a link connecting one arm of said bell crank with the other arm of said first named bell crank lever, an operating arm pivoted inwardly of its ends to said casing, the pivot of said operating arm disposed between the pivotal connections of said first and second bell crank levers with said housing and oset with respect thereto, and a link connecting one end of said operating arm with the other arm of said second bell crank lever.

6. In a drop hook, an elongated housing, a fixed jaw in said housing at the lower end thereof, a swinging jaw pivoted intermediate its ends and in its longitudinal axis within said housing with its lower end movable into and out of load supporting position with said fixed jaw, a load link pivoted at its inner end to the upper end of said jaw beyond the longitudinal axis of said jaw and normally extending transversely of said jaw across said axis, a bell crank pivoted at the end of one of its arms to said housing and intermediate its ends to the outer end of said load link, the pivots of said inner link end and said bell crank arm normally disposed in transverse alignment below the pivotal connection of said link with said lever, a second bell crank pivoted intermediate its ends in said casing in substantially the longitudinal axis thereof, a link cermecting one arm of said second bell crank with the other arm of said first bell crank, the last named pivot normally disposed out of alignment with the pivot of said second bell crank and the pivot of said other arm of the iirst named bell crank, an operating lever pivoted inwardly of its ends at one side of said housing, an arm projecting laterally from one end of said lever into said housing, and a link connecting the end of said arm with the other arm of said second bell crank lever.

References Cited in the file of this patent UNITED STATES PATENTS 1,423,301 Betcher July 18, 1922 2,333,621 Lobelle Nov. 2, 1943 2,425,309 Ennis Aug. 12, 1947 FOREIGN PATENTS 246,892 Germany May 17, 1912

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