US3425508A - Extension ladder - Google Patents

Description

Feb. 4, 1969 E. w. FAULSTICH 3,425,508

EXTENSION LADDER Filed Sept. 21, 1967 5y 7 0M, ZMA hL/w rm I 977-02445 s s United States Patent 3,425,508 EXTENSION LADDER Eugene W. Faulstich, 209 S. Main St., Algona, Iowa 50511 Filed Sept. 21, 1967, Set. N0. 669,462 US. Cl. 182-18 11 Claims Int. Cl. E06c /34, 5/44 ABSTRACT OF THE DISCLOSURE An extension ladder anchored at its lower end on the top of a truck with a support member movably engaging the ladder on its lower side for raising and lowering the ladder. An electrically powered shaft connected to a cable simultaneously extends and raises the ladder and is co-ordinated to maintain the outer end of the ladder in a common plane while being raised or lowered. Limit switches may be provided to limit the raising and the lowering of the ladder. Automatic height measuring means may be employed.

The extension boom or ladder of this invention may be positively anchored in place on top of a truck or similar base and may be raised and extended simultaneously such that the outer end of the ladder will move in a common vertical plane during the raising and lower operation. It is thus apparent that the ladder may be initially placed against a pole or the like and then moved up the pole 'without moving towards or away from the pole. The

ladder of this invention is well suited for mounting on top of a panel truck or the like and includes limit switches for limiting the extension and raising of the ladder as well as the lowering and contraction of the ladder to its transport and storage position horizontally disposed on top of the panel truck.

These and other features and advantages of this invention will become readily apparent to those skilled in the art upon reference to the following description when taken into consideration with the accompanying drawings, wherein:

FIG. 1 is a side elevation view of the extension ladder mounted on top of a panel truck positioned closely adj acent to a utility pole;

FIG. 2 is a top plan view of the extension ladder on top of the truck;

FIG. 3 is an enlarged in scale fragmentary view of the ladder mounted on the top of the truck;

FIG. 4 is a fragmentary view of the actuating means carried on the power cable and the limit switches operated thereby;

FIG. 5 is a side elevation view of the ladder in its raised and extended position adjacent a utility pole;

FIG. 6 is a perspective view of the cable arrangement connected to the ladder sections for operating the ladder and showing the ladder in its lowered contracted condition;

FIG. 7 is a schematic view similar to FIG. 6 but showing the ladder in its extended raised condition; and

FIG. 8 is a schematic of the electrical circuitry for the motor that operates the extension ladder.

3,425,508 Patented Feb. 4, 1969 The extension ladder of this invention is referred to generally in FIG. 1 by the reference numeral 10 and is shown mounted on the top 12 of a panel truck 14 which is positioned adjacent a utility pole 16.

The extension ladder as shown in FIG. 3 involves a conventional pair of lower and outer extension sections 18 and 20 respectively. The lower section 18 is pivotally anchored by plates 22 to the rear of the top 12 of the panel truck 14. Forwardly of the anchor plates 22, a U- shaped support member 24 is pivotally connected to the top 12 of the panel truck 14. The outer end 26 extends upwardly and engages the lower side of the lower ladder section 18 as best seen in FIG. 5. The support member 24 may pivot from a perpendicular position to the ladder as seen in FIG. 5 to a generally horizontal position as seen in FIG. 1 wherein support feet 28 on the support member 24 engage the forward end of the top 12 of the panel truck 14 as seen in FIG. 1.

The ladders are extended and raised by a motor 30 connected to a power shaft 32 rotatably extending -between the legs of the lower ladder section 18. A cable reel 34 is mounted between the legs on the shaft 32 and is connected to the opposite ends of a cable 36 which extends over the pulley 38 secured to an outer rung 40 on the lower ladder section 18. As seen in FIGS. 6 and 7 the cable 36 is connected to the support member 24 at 44 and is connected to a ladder rung 46 on the lower ladder section 18 at point 48.

The control system for limting the operation of the motor 30 is shown in FIGS. 4 and 8 and includes a pair of actuating elements 50 and 52 mounted on the cable 36 for engagement with the springs 54 and 56 respectively which in turn are connected to limit switch fingers 58 and 60 respectively. The actuating elements 50 and 52 may be cable clamps or the like and the springs 54 may have eyes formed on their outer ends through which the cable extends and thus the cable clamps will engage the spring loop and actuate the limit switches at the appropriate times. The limit switch fingers 58 and 60 are integrally a part of a limit switch unit mounted on a ladder rung 72 of the lower ladder section 18. An up and down master control switch 72 is provided in the cab of the panel truck 14 in convenient reach of the operator of the truck.

In operation it is seen that the truck is first driven up to the pole as seen in FIG. 1 wherein the outer end of the outer section 20 is closely adjacent to the pole. Next the switch 72 is operated by moving it to its up position whereby the motor 30 rotates the shaft 32 in the direction indicated by the arrow in FIG. 7 causing the outer ladder section 20 to be extended and simultaneously causing the support member 24 to be raised thereby raising the entire extension ladder unit 10. As the ladder reaches its maximum extension the actuating element 50 on the cable 36 will operatively actuate the limit switch finger 50 and reverse the polarity of the electrical circuit such that when the ladder is to be lowered the master switch 72 in the cab of the truck is moved to the down position and then the shaft 32 is rotated in the direction indicated by the arrow 82 in FIG. 6 causing the support member 24 to be lowered to the horizontal position of FIG. 1 and the outer ladder section 20 to be retracted. A conventional ladder may be employed to enable the operator to reach the top of the truck and the extension ladder unit 10. After the ladder is fully extended it may be desired to move the truck slightly forward for the outer end of the outer section to engage the pole 16 to provide a rigid support at the outer end.

It is desirable at times to know the elevation above the ground of the outer end of the ladder as for instance in complying with the law regarding providing a minimum clearance above the ground for signs or the like. Accordingly, measuring indicia 100 is provided along the length of the outer ladder section 20. This scale of indicia is such that as it registers with the outer end 102 for example of the inner ladder section 18 it will accurately indicate the elevation above the ground of the outer end of the outer ladder 20 as seen in FIG. for example. Thus by extending the ladder section 20 until the appropriate reading is obtained the desired height of the outer end of the ladder 20 may be obtained.

Thus it is seen that the novel and simplified structure of this invention makes it possibel to provide extremely fast accurate operation of an extension or boom or the like.

Some changes may be made in the construction and arrangement of my extension ladder without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim:

1. An extendable boom, comprising,

a base,

an extendable boom anchored to said base at its lower end,

support means engaging said boom remotely from said lower end,

power means for extending and raising the boom, and

co-ordinating means associated with said power means and support means for extending and raising the boom simultaneously such that the otuer end of the boom while being raised and lowered is maintained in substantially a common vertical plane.

2. The structure of claim 1 wherein said boom includes two sections and said co-ordinating means includes a cable connected to said power means and coupled to the outer boom section and to said support means to vary the length and angle of said boom.

3. The setructure of claim 2 wherein said support means is movable along said boom by said cable during raising and lowering of said boom.

4. The structure of claim 3 wherein said support means is further defined as a support structure pivotally anchored to said base and engaging said boom for movable engagement therewith.

5. The structure of claim 4 wherein said support structure is anchored to said base forwardly of the lower end of said lower section anchored to said base and the upper end of said support structure movably engages the lower side of said boom, and said cable is connected to said upper end of said support structure.

6. The structure of claim 5 wherein said boom is further defined as being an extendable ladder having upper and lower sections.

7. The structure of claim 5 wherein a control system is associated with said power means and said co-ordinating means, a limit switch connected to said power means is disposed to be operated by an actuating element on said cable when said boom has been raised to a predetermined height.

8. The structure of claim 7 wherein a second limit switch is disposed to be operated by an actuating element on said cable when said boom has been lowered to a predetermined height.

9. The structure of claim 5 wherein said base is further defined as being the top side of a vehicle.

10. The structure of claim 8 wherein said power means is an electric motor and said cable extends over a pulley on the upper end of said lower section with both ends extending downwardly along said lower section and terminating in anchoring engagement with a transversely extending power shaft connected to said motor whereby during operation one end of said cable is unwound from said shaft and the other end is wound onto said shaft.

11. The structure of claim 1 wherein measuring indicia is provided on said boom, and said indicia being calibrated to register the height of the outer end of said boom above the ground as said boom is extended and raised.

References Cited UNITED STATES PATENTS 489,628 1/1893 Colleret 182-66 640,645 1/ 1900 Fall 182--66 2,238,665 4/1941 Troche 182-66 2,667,296 1/ 1954 Troche 182-68 2,981,362 4/1961 Troche 182-67 REINALDO MACHADO, Primary Examiner.

U.S. Cl. X.R.

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