Portable folding crane

A portable folding crane which includes an elongated base member having first and second axial extremities and first and second elongated telescoping legs. Each of the legs has first and second axial extremities and each of the first axial extremities is pivotally connected proximate to respective axial extremities of the base member. A telescoping column member has first and second axial extremities and the first axial extremity of the telescoping column member is pivotally connected to the base member. A boom member has first and second axial extremities and the second axially extremity of the telescoping column member being the first axial extremity of the boom member are pivotally connected. Apparatus for urging the boom member to pivot with respect to the column member is also provided.

BACKGROUND OF THE INVENTION 
The invention relates to cranes and particularly to cranes that are 
portable and folding for maximum portability and ease of storage. A large 
number of cranes and derricks have been provided which typically do not 
really fold. Instead, they may be disassembled to facilitate movement and 
storage. Such arrangements are not convenient to store or use. Examples of 
prior art includes the apparatus shown in the U.S. Pat. Nos. 494,473 and 
4,508,233. 
It is an object of the invention to provide apparatus which will fold very 
compactly. 
It is another object of the invention is to provide apparatus which can be 
easily manufactured. 
Another object of the invention is to provide apparatus which can be 
manufactured inexpensively. 
SUMMARY OF THE INVENTION 
It has now been found that these and other objects of the invention may be 
attained in a portable folding crane having an elongated base member which 
has first and second axial extremities and first and second elongated 
telescoping legs. Each of the legs has first and second axial extremities 
and each of the first axial extremities are pivotally connected poximate 
to respective axial extremities of the base member. A telescoping column 
member has first and second axial extremities. The first axial extremity 
of the telescoping column member is pivotally connected to the base 
member. A boom member has first and second axial extremities. The second 
axially extremity of the telescoping column member and the first axial 
extremity of the boom member being pivotally connected to the second axial 
extremity of the column member. The apparatus also includes means for 
urging the boom member to pivot with respect to the column member. 
The column member may pivot in a first plane and the first and second legs 
may pivot in a second plane about the base member. A spanner member may 
engage the first and second legs at respective points and detachably 
engage the first and second legs at respective points spaced from the 
first axial extremities thereof. The column member may include a knee 
shaped portion at the first axial extremity and the column member may have 
the pivotable connection to the base member on the knee section carried on 
the knee section. 
A tensioning member may extend from the second extremity of the column 
member to the base member. The tensioning member may include first and 
second rods. The rods may be elongated and each may have first and second 
axial extremities. The first and second rods may be connected by stop 
members respectively attached to axial extremities of the rods. The stop 
members may permit the first and second rods to move relative to each 
other until the stop members limit further relative axial movement. The 
stop members may be each fixed to one of the rods and each may have an 
opening therein which is dimensioned for free passage along the axial 
extent of the other rod and will not pass over the stop on the other rod.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIGS. 1-6 there is shown the folding portable crane 10 in 
accordance with one form of the invention. The apparatus includes first 
and second telescoping legs 12, 14. Each leg 12, 14 is manufactured of two 
concentric box shaped channels which are dimensioned and configured for 
relative sliding axial movement. Typically, the respective axial sections 
of each leg 12, 14 will be secured by a pin or ball detent such as 16. 
Casters 18, 19 are mounted on the lower surface of the first and second 
legs 12, 14 to allow ease of movement of the crane 10 as well as the crane 
when loaded with an object such as an automobile engine. Each leg member 
12, 14 has a first axial extremity and a second axial extremity. As shown 
in FIGS. 1 and 2 the leg members 12, 14 are extended to their maximum 
length. The second axial extremities of the leg member 12, 14 as used 
herein refers to the free end of the leg members 12, 14 and the first 
axial extremities refers to the opposite end which is pivotally connected 
to a base member 20. 
The pivotal connection between the base member 20 and the leg members 12, 
14 allow relative movement in a first plane which will be understood to be 
generally horizontal. 
The base member 20 is, in one form of the invention, a generally 
cylindrical tube, as best seen in FIG. 2, about which is pivoted a 
telescoping column member 24 which is also elongated and has first and 
second axial extremities. The first axial extremity is provided with a 
knee section 26 which engages the tube shaped base member 20 for relative 
pivotal movement. More specifically, the pivotal connection between the 
knee 26 and the base member 20 is best seen in FIG. 2 which best 
illustrates the concentric cylindrical sections which provide the 
necessary pivotal connection. FIG. 2 also illustrates the pin connections 
28, 28 which respectively join the first axial extremities of the leg 
members 12, 14 to the base member 20. 
An elongated spanner member 36, which is fabricated from an L-shaped 
channel, is detachably secured by bolts or pins 88,88 to both the first 
and second legs 12, 14 at points spaced from the first axial extremities 
of these legs. 
Secured to the upper or second axial extremity of the telescoping column 
member 24, is a boom member 38 which is also telescoping in the same 
manner as the column 24 and the legs 12, 14. A pin connection 40 joins the 
boom member 38 to the column member 24. As in the leg members 12, 14, the 
boom member has a detent or pin 42 to secure the axial position of the 
sections of the boom member 38. A clevis 44 is secured by a pin 46 to the 
free end of the boom member 38. 
A hydraulic cylinder 50 is secured by pins 52, 54 to the boom member 38 and 
the column member 24. 
A tensioning member is provided to stabilize the position of the column 
member 24. In the preferred embodiment this tensioning member is a pair of 
rods 60, 62 as best seen in FIG. 1. These rods have respective stop 
members 66, 64 disposed at the respective ends of the rods. Each of the 
stop members has a hole (not shown) which allows free passage of the other 
rod but not passage over the other stop member. More particularly, the rod 
60 has stop member 66 fixed to the end thereof which has an opening which 
allows the passage of the axial extent of the rod 62 but not the passage 
of the stop 64. Thus, the rods 60, 62 are free to move to the position 
shown in FIG. 1 when the column member 24 is fully extended and locked 
place by a pin, bolt or other latching device 70. The rod 60 is secured to 
the upper or second axial extremity of the column member 24. The rod 62 is 
secured to the base member 20. The boom member 38 is telescoped to its 
shortest possible length. 
When the apparatus is to be folded, the column member 24 is telescoped to 
its shortest possible length as are the legs 12, 14 as shown in FIG. 3. 
The rods 60, 62 have moved to a side by side axially overlapping 
relationship as best shown in FIG. 3. 
Referring now to FIG. 4 there is shown a top view corresponding to FIG. 3 
which illustrates the removal of the spanner member 36 by removal of the 
bolts or pins 88, 88, and the subsequent spreading of the legs 12, 14 by 
pivoting them about their respective pivot points on the base member 20. 
Referring to FIG. 5 there is still shown still further step wherein the 
boom member 38 is folded toward a substantially parallel side by side 
relationship with the column member 24 as best seen in FIG. 6. 
Simultaneously, the hydraulic cylinder 50 is pivoted to substantially a 
parallel side by side relationship to the boom member 38. Simultaneously, 
the legs 12, 14 are also pivoted around the base member 20. 
FIG. 6 illustrates the fully folded crane 10. It will be understood that 
the crane 10 may be easily moved when folded in this manner as well as 
stored. It will be further understood that the crane 10 may be stored 
either in the illustrated position or in an upright position wherein the 
apparatus is at a 90 degree angle with respect to the position shown in 
FIG. 6. 
The invention has been described with reference to its illustrated 
preferred embodiment. Persons skilled in the art of cranes and the like 
may, upon exposure to the teachings herein, conceive other variations. 
Such variations are deemed to be encompassed by the disclosure, the 
invention being delimited only by the appended claims.