Apparatus for lifting concrete panels

Abstract

An apparatus for lifting precast concrete panels includes a lifting body having a forward portion adapted to engage in an anchor head, a latch yoke pivotally connected to a rearward end of the lifting body and including a safety latch cooperating with the forward portion of the lifting body to lock an anchor head to the forward portion, a release yoke pivotally attached to the lifting body for movement between locked and release positions and including a cam roller for urging effective during movement of the release yoke to its release position to cause the latch yoke to pivot to a release portion, and a lifting bail pivotally attached to the forward portion. The lifting body release yoke includes a safety pin block extending upwardly from a rearward portion thereof adjacent to the rearward end of the latch yoke. The latch yoke and safety pin block include bores which are in registry with each other when the apparatus is oriented to a locked position. A safety pin is inserted into the bores and prevents relative pivotal movement between the latch yoke and lifting body release yoke, and is removable from the bore by a lanyard which is pulled by a worker.

Description

urges acts as a cam against the underside of the latch yoke 35, causing it to pivot relative to the lifting body 12, thereby raising the safety latch 40 out of the void 42 to allow the anchor head 21 to disengage completely disengage from the slot 20. The pivotal movement of the release yoke 28 will continue until the apparatus 10 assumes the configuration shown in FIG. 4, which is the release position. At that time, the entire apparatus will swing free of the panel 24.

In contrast, the prior art lifting apparatus, generally designated 91 and shown in FIG. 1, includes a safety pin 76' which extends through a bore 92 formed in the boss 86' of the release yoke 28'. The safety latch 40' includes an upper extension 94 that includes a second bore 96, positioned to be in registry with the first bore 92 when the device 91 is in the locked position. Accordingly, the safety pin 76' extends through both bores 92, 96 and prevents relative movement between the release yoke 28' and the latch yoke 35'.

Such a design, in which the positive connection between the latch yoke 35' and the release yoke 28' is located forwardly of the pivot point 29', and directly above the forward portion 14', has been found to be less reliable in preventing the inadvertent release of the apparatus 91 from an anchor 22. This is believed to result from the positive engagement at that location being more susceptible to variations in dimensional tolerances of the components of the apparatus 91, as well as locational tolerances of the pivot connections.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention.

Claims

1. In an apparatus for lifting precast concrete panels of the type including a lifting body having a forward portion adapted to fit within an anchor recess and engage an anchor head, a latch yoke pivotally connected having a pivot connection to a rearward end of said lifting body for movement between locked and release positions and including a safety latch at a forward end thereof cooperating with said forward portion of said lifting body to lock an anchor head to said forward portion when said latch yoke is pivoted to a said locked position, a release yoke pivotally attached to said lifting body for movement between locked and release positions with respect to said latch yoke and including cam means for urging effective during movement of said release yoke from said locked position to said release position thereof to cause said latch yoke to pivot to a said release position thereof wherein said safety latch is displaced from said forward portion, and a lifting bail pivotally attached to said forward portion, the improvement comprising:

locking means extending between a rearward end of said latch yoke and said a rearward end of said lifting body release yoke, and positioned rearwardly of said urging cam means and said pivot connections connection between said lifting body, and latch yoke, and release yoke, for preventing pivotal movement of said latch yoke relative to said lifting body when said latch release yoke is in said locked position thereof, thereby locking said apparatus to said anchor head.

2. The apparatus of claim 1 wherein said pivot preventing locking means includes a pair of bores formed in said latch yoke and said lifting body release yoke, said bores being positioned to be aligned with each other when said latch yoke is yoke are in said locked position thereof; and a safety pin sized to be removably inserted into said bores, thereby providing a rigid connection between said latch yoke and said lifting body and preventing relative pivotal movement therebetween.

3. The apparatus as claim 2 wherein said release yoke includes a safety pin block extending outwardly therefrom adjacent to toward said rearward end of said latch yoke and including one of said bores.

4. The apparatus of claim 3 wherein said safety pin block bore includes detent means for retaining said safety pin therein.

5. The apparatus of claim 4 wherein said bores, when aligned together form a combined bore extending rearwardly and angled outwardly from said apparatus through said safety pin block into said latch yoke in a direction inclined toward said lifting body.

6. The apparatus of claim 5 wherein said safety pin block is fixed relative to a remainder of said release yoke.

7. In an apparatus for lifting precast concrete panels of the type including a lifting body having a forward portion adapted to fit within an anchor recess and engage an anchor head, a latch yoke having a rearward end attached to a rearward portion of said body at a first pivot connection for movement between locked and release positions and including a safety latch cooperating with said forward portion of said body to lock an anchor head to said forward portion when said latch yoke is pivoted to a said locked position, a release yoke connected at a midportion thereof of to said rearward portion of said body at a second pivot connection forward of said first pivot connection for movement between locked and release positions and including cam means, located forward of said second pivot connection, for urging and effective during movement of said release yoke from said locked position to said release position thereof to cause said latch yoke to pivot to a said release portion thereof wherein said safety latch is displaced from said forward portion, and a lifting bail pivotally attached to said forward portion of said lifting body, the improvement comprising:

said latch yoke including a first bore in a said rearward end thereof;

said lifting body release yoke including a safety pin block extending upwardly from a rearward end of said rearward portion therefrom on the opposite side of said second pivot connection from said cam means toward said latch yoke and including a second bore, located to be aligned with said first bore when said apparatus release yoke is in said locked position, and forming with said first bore a combined bore angled rearwardly and upwardly from said apparatus extending into said yokes in a direction inclined toward said lifting body;

a safety pin sized to slidably engage for slidable engagement within said combined bore, thereby preventing relative pivotal movement between said latch yoke and said lifting body; and

detent means for releasably retaining said safety pin within said combined bore.