US 3,978,989 AGranted

Extensible and collapsible portable derrick

OwnerFred Avila, Jr.inventor

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Abstract

An extensible and collapsible portable derrick in which the various parts are made from a light weight metal and in which the parts can be disassembled and arranged in compact units, light enough in weight and small enough in size to be readily transportable by a person. The device is primarily designed to be used by operators who use tar paper and gravel for covering flat roofs of buildings whether or not the roofs are provided with parapets.

Claims1

Dependent claims

A portable derrick comprising:

a. a base including a hollow upright with hinged base members swingable outwardly into a plane that extends at right angles to the axis of said upright;
b. hinged braces interconnecting the outer ends of said base members with said upright and each consisting of two parts hinged together with removable clips holding said two parts in lineal alignment with each other when said base is in operative position;
c. an intermediate unit having an extension removably and slidably receivable in said upright with means for securing said intermediate extension in said upright in adjusted position;
d. a transversely extending bracket, angle-shaped in cross section and having the midpoint of its front face permanently secured to the extension of said intermediate unit, the top of said bracket lying in a plane which extends at right angles to the axis of said extension;
e. a hook disposed on each side of said extension and being adjustably received in sleeves secured to the top of said bracket, the outer ends of said hooks extending downwardly and cooperating with the front face of said bracket to form shoulder engaging members when said intermediate unit is freed from the hollow upright of said base when it is desired to carry the intermediate unit independently of said base;
f. means carried by said sleeves for securing said hooks in adjusted position therein for permitting said hooks to contact with one side of a building parapet and the front face of said bracket being disposed adjacent to the other side of the parapet, and hand screws on the front face for clamping the bracket to the parapet;
g. a top unit having a cap removably and rotatably mounted on the top of the extension for said intermediate unit;
h. an extensible arm pivotally secured to said cap and being swingable from a closed position, where the length of the arm parallels the axis of said cap, into an operative position where said arm projects radially from said cap, and a pulley mounted at the outer end of said arm;
and
i. a hinged brace for supporting said arm in operative position, said cap and arm being rotatable around said extension.

7 more elements

Dependencies are inferred from the claim text.

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Abstract

A portable derrick comprising:

a. a base including a hollow upright with hinged base members swingable outwardly into a plane that extends at right angles to the axis of said upright;
b. hinged braces interconnecting the outer ends of said base members with said upright and each consisting of two parts hinged together with removable clips holding said two parts in lineal alignment with each other when said base is in operative position;
c. an intermediate unit having an extension removably and slidably receivable in said upright with means for securing said intermediate extension in said upright in adjusted position;
d. a transversely extending bracket, angle-shaped in cross section and having the midpoint of its front face permanently secured to the extension of said intermediate unit, the top of said bracket lying in a plane which extends at right angles to the axis of said extension;
e. a hook disposed on each side of said extension and being adjustably received in sleeves secured to the top of said bracket, the outer ends of said hooks extending downwardly and cooperating with the front face of said bracket to form shoulder engaging members when said intermediate unit is freed from the hollow upright of said base when it is desired to carry the intermediate unit independently of said base;
f. means carried by said sleeves for securing said hooks in adjusted position therein for permitting said hooks to contact with one side of a building parapet and the front face of said bracket being disposed adjacent to the other side of the parapet, and hand screws on the front face for clamping the bracket to the parapet;
g. a top unit having a cap removably and rotatably mounted on the top of the extension for said intermediate unit;
h. an extensible arm pivotally secured to said cap and being swingable from a closed position, where the length of the arm parallels the axis of said cap, into an operative position where said arm projects radially from said cap, and a pulley mounted at the outer end of said arm;
and
i. a hinged brace for supporting said arm in operative position, said cap and arm being rotatable around said extension.

7 more elements