Title:
DEVICE FOR PREVENTING FALLING DOWN OF LIFTER OF FIRE FIGHTING LADDER-EQUIPPED VEHICLE
United States Patent 3693755


Abstract:
A falling down-preventive cable is provided in addition to a lifting cable, with the intermediate portion of said falling down-preventive cable being wrapped a plurality of turns around a drum or pulley provided in a lifter, and brake means for said drum or pulley is held inactive during normal operation by the weight of the lifter, thereby permitting the up and down movements of the lifter. Upon breakage of the lifting cable, the brake means is actuated to control the rotation of the drum or pulley and henceforth said falling down-preventive cable prevents the lifter from falling down. Other advantages and details of the construction will be made clear.



Inventors:
TERAYAMA FUSAJI
Application Number:
05/060573
Publication Date:
09/26/1972
Filing Date:
08/03/1970
Assignee:
MORITA FIRE PUMP MFG. CO. LTD.
Primary Class:
Other Classes:
182/145, 212/230, 212/239
International Classes:
E06C5/36; (IPC1-7): E06C7/16
Field of Search:
182/103,102,101,66,67,68,145 187
View Patent Images:
US Patent References:
3220509Special purpose suspended staging1965-11-30Fisher
0837006N/A1906-11-27
0287042N/A1883-10-23
0202876N/A1878-04-23



Foreign References:
GB359942A
Primary Examiner:
Machado, Reinaldo P.
Claims:
I claim

1. The combination, in a fire fighting vehicle, of

2. A combination as claimed in claim 1, wherein:

3. A combination as claimed in claim 1, in which said second cable has a plurality of half-turns engaged with said capstan means.

4. A combination as claimed in claim 3, in which said capstan means comprises a plurality of pulleys in two rows with each of which said second cable has a half-turn engagement.

5. A combination as claimed in claim 1, wherein:

6. A combination as claimed in claim 5, wherein said last named means comprises a lever carried by said lifter having a brake applying and a brake releasing position, said hoisting cable being connected to said lever for normally holding the same in its brake releasing position but allowing the same to move to its brake applying position on breakage of said hoisting cable.

Description:
BACKGROUND OF THE INVENTION

The present invention relates to a device for preventing the falling down of the lifter of a fire fighting ladder-equipped vehicle upon breakage of the lifting cable thereof.

FIELD OF THE PRIOR ART

A lifter which moves up and down along an extended ladder is operated by winding and unwinding a cable.

Therefore, it becomes necessary to provide a device for preventing falling down upon breakage of the cable. At present, the known devices for preventing the falling down of the lifter include a type which comprises cable clamp means provided at a suitable place on a lifter moving up and down along an extended ladder, a lifting cable for the lifter fastened to the operative lever of the cable camp means, said cable clamp means being kept inactive by the weight of the lifter except when the cable breaks, a second cable for preventing the falling down of the lifter stretched along an extended ladder and extending between the cable clamp bodies of the cable clamp means, said cable clamp means being adapted to be actuated as a result of breakage of the lifting cable to clamp the lifting cable so that henceforth the lifter is prevented from falling down. However, such a lifter weighs more than 100kg, and it is too much for a device of the type described to reliably brake such a heavy lifter simultaneously with breakage of the cable. Thus, the prior art braking device is not so suitable as to fully meet the requirements.

OUTLINE OF THE INVENTION

The present invention provides an improved device for preventing the falling down of the lifter located in juxtaposed relation to the aerial ladder of a fire fighting ladder-equipped vehicle, characterized in that said device comprises a capstan means, i.e. drum or pulley means, mounted for forward and reverse rotations in the lifter, said drum or pulley means being provided with brake means, a lifting cable secured to the lifter through said brake means, said brake means being adapted to be kept inactive by the weight of the lifter except when the lifting cable breaks, a lifter falling down-preventive second cable provided separately from said lifting cable and having the intermediate portion thereof wrapped a plurality of half turns around said drum or pulley, said brake means being adapted to be actuated by brake control means upon breakage of the lifting cable to brake the drum or pulley so that henceforth the falling down of the lifter is prevented by frictional force acting at the place of wrapping where the falling down-preventive cable is wrapped around the drum or pulley.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings showing the preferred embodiments of the invention:

FIG. 1 is a side view of the ladder portion of a fire fighting ladder-equipped vehicle constructed in accordance with the invention;

FIG. 2 is a side view of the ladder portion of a fire fighting ladder-equipped vehicle having another construction according to the invention;

FIG. 3 is a perspective view of brake means constructed in accordance with the invention; and

FIGS. 4 and 5 show other embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

An aerial ladder 1 shown in FIG. 1 consists of five ladders 11 - 15 fitted together for expansion and contraction, the base ladder 11 being tiltably pivoted to a ladder support 4 on a turntable 3 provided on a vehicle body 2. The tilting motion of the ladder 11 is effected by a hydraulic cylinder 5. Further, the expanding and contracting motions of the aerial ladder 1 are effected by winding and unwinding a ladder expanding and contracting cable 8 by means of a winder 7 provided on a pivot shaft 6. Since the entraining system for the expanding and contracting cable 8 is a known one, description thereof is omitted.

A lifter 9 is so mounted that it can be moved along the extended aerial ladder 1. The lifter is suspended by raising and lowering means comprising a hoisting or lifting cable 11 entrained around a sheave 10 on the front end of the ladder, the other end of said cable 11 being wrapped around a winder 12 on the turntable 3, so that the raising and lowering of the lifter are effected by winding and unwinding the cable 11. In addition, the lifting cable 11 is not directly fastened to the lifter. It is fastened to the operative lever 14 of brake means 13 which is provided in the lifter for controlling a drum of pulley 15 mounted for forward and reverse rotations in the lifter 9. The intermediate portion of a lifter falling down-preventive cable 16 is wrapped 2- 3 turns around said drum or pulley 15. The lifter falling down-preventive cable extends along the entire length of the extended ladder 1. In the case shown in FIG. 1, the cable 16 has its front end 161 fastened to the front end of the ladder 1 and the lower end wrapped around a winder 17 of the turntable 3. In view of this arrangement, it becomes necessary to wind and unwind the falling down-preventive cable 16 by said winder 17 in accordance with the expansion and contraction of the aerial ladder 1.

FIG. 2 shows another embodiment wherein the lifting cable 11 and falling down-preventive cable 16 are entrained by a different system. The other arrangements, however, are the same as those shown in FIG. 1 and the common members are indicated by the same reference characters as those used in FIG. 1. Thus, in FIG. 2, the lifting cable 11 has its front end fastened to the operative lever 14 of the brake means 13 of the lifter 9 and is entrained around the pulley 10 provided on the front end of the uppermost ladder 14 and is then entrained in zigzags under tension around successive pulleys 18 provided at the front and rear ends of the ladders 11, 12, 13, 14 and is finally led to the winder 12.

Further, the falling down-preventive cable 16 has one end thereof fastened at 19 to the lower end of the lowermost ladder 11 and is wrapped 2- 3 turns around the drum of pulley 15 in the lifter 9, entrained in bights or zigzags under tension seriatim around successive pulleys 21 provided at the front and rear i.e. upper and lower ends of the ladders 14, 13, 12, 11 and is finally fastened at 22 to the lowermost ladder 11 thus making it fast over the member 21 near the top thereof.

With the above-mentioned arrangement, even if the aerial ladder is expanded and contracted, the lifting cable 11 and falling down-preventive cable 16 remain permanently under tension, so that there is no need to wind or unwind these cables 11 and 16 in accordance with the expansion and contraction of the aerial ladder.

The above-mentioned brake means 13 is secured to the lifter 9, embodiments of the brake means being shown of FIGS. 3 and 5.

Thus, in FIG. 3, the lifter carries a rotatable shaft 23 journaled in bearings 24 and 25. The rotatable shaft 23 extends transversely of the direction of up and down motions of the lifter 9. The drum or pulley 15 is fixed at the central portion of the rotatable shaft 23. The drum or pulley has three annular grooves. These annular grooves may be formed in the outer peripheral surface of the drum or pulley or they may be formed by joining three pulleys together. In FIG. 3, the numerals 26 and 27 denote guide pulleys secured to shafts 28 and 29 journaled before and behind the rotary shaft 23 and extending parallelly to the latter. The falling down-preventive cable 16 has its intermediate portion wrapped successively around the groove at one end of the drum or pulley 15, around one guide pulley 26, then one turn around the middle groove of the drum or pulley 15, then around the other guide pulley and finally around the other guide pulley. This arrangement prevents the drum or pulley 15 from being displaced to either side by the falling down-preventive cable 16. A brake drum 30 is secured to one end of the rotatable shaft 23. Two semicircular brake shoes 31, 32 are inserted in the brake drum 30. The brake shoes 31, 32 are pivoted on a pin 33 at one of their respective ends and a cam 34 is interposed between the free ends thereof. The free ends of the brake shoes 31, 32 clamp the cam 34 by means of a spring 35. The cam 34 has a support shaft 36 integral therewith. The support shaft 36 and pin 33 for the brake shoes 31, 32 are journaled by the frame of the lifter 9 laterally of the open end of the brake drum 30. An arm 37 is secured to the end of the support shaft 36 of cam 34, the free end of said arm being connected to the operative lever 14 by a link 38. The operative lever 14 is pivotally connected to the frame of the lifter 9 by a pin 39. The operative lever 14 is acted on permanently by a spring 40, serving to spread the brake shoes 31 and 32 through the cam 34. The lifting cable 11 is fastened to the operative lever 14. The wright of the lifter 9 serves to normally pull the operative lever 14 against the power storing action of the spring 40 until it bears against a stop 70 projecting from the frame of the lifter, i.e. lies in its brake releasing position as shown in solid lines in FIG. 3. Thus, if the lifting cable 11 breaks, the stored power means 40 moves the lever 14 to its brake applying position, and the brake is applied to the rotatable shaft 23 as shown in chain lines in FIG. 3 to stop the lifter 9. While FIG. 3 shows the brake means embodied in the form of an internal spread type, an external band type brake may be used.

FIG. 4 shows another embodiment of the brake means, wherein a shaft 43 having a round shaft portion 41 and a square shaft portion 42 is fixedly supported in the lifter 9 through brackets 44 and 45. A pulley 47 having a conical projecting sleeve 46 on one lateral surface thereof is rotatably mounted on the round shaft portion 41 of the fixed shaft 43 through ball bearings 48. The intermediate portion of the falling down-preventive cable 16 is wrapped one turn around the pulley 47. A slidable sleeve 49 adapted to be intimately fitted on the conical projecting sleeve 46 of the pulley 47 at a certain time is mounted on the square shaft portion 42 of the fixed shaft 43 and a spring 50 acts permanently on the slidable sleeve 49 to urge the latter toward the conical projecting sleeve 46. The outer peripheral surface of the slidable sleeve 49 is provided with a groove 51 in which a shifter rod 53 at the other end of the operative lever 52 engages. The lifting cable 11 is fastened to the operative lever 52. Thus, when the lifting cable 11 is tensioned under the weight of the lifter, the operative lever 52 has been pulled upwardly as it turns counterclockwise around a pivot 54, with the slidable sleeve 49 being displaced toward the right as viewed in the drawing as shown in chain lines, compressing the spring 50. Therefore, the pulley 47 is in its free state. Thus, upon breakage of the lifting cable 11, the spring 50 brings the slidable sleeve 49 into intimate engagement with the conical projecting sleeve 46 of the pulley 47 to brake the pulley 47, thereby positively preventing the falling down of the lifter 9 by means of the falling down-preventive cable 16. In FIG. 4, the numeral 55 denotes a rubber lining secured to the slidable sleeve 49.

FIG. 5 shows a modification of the brake means shown in FIG. 4. In this modified embodiment, the falling down-preventive cable 16 is entrained around a plurality of pulleys in two rows. In this case, increased frictional resistance is exerted between the falling down-preventive cable 16 and pulleys so that the falling down of the lifter 9 can be prevented more reliably. In FIG. 4, the numerals 56 and 57 denote fixed shafts fixed to brackets 58 and 59. One fixed shaft 56 is of the same construction as the fixed shaft 43 shown FIG. 4. A pulley 61 having a conical projecting sleeve 60 on one lateral surface thereof is rotatably mounted on the fixed shaft 56, and there is also mounted thereon a slidable sleeve 62 adapted to be intimately fitted on said conical projecting sleeve at a certain time. A spring 63 permanently urges the slidable sleeve 62 toward the conical projecting sleeve 60 of the pulley 61. The outer peripheral surface is provided with a groove 64 in which a shifter rod 66 at the other end of the operative lever 65 engages, and the lifting cable 11 is fastened to the operative lever 65, as in the case of FIG. 4. Further, a pulley 67 is rotatably mounted on the other fixed shaft 57, and the falling down-preventive cable is entrained around this pulley 67 and around the pulley 61 on the fixed shaft 56. The operation of the brake means shown in FIG. 5 is the same as that of the brake means shown in FIG. 4.

While the respective brake means shown in FIGS. 3 to 5 are automatically actuated to brake the lifter 9 in conjunction with breakage of the lifting cable 11, it is also possible to manually operate the operative lever.

It will be seen from the foregoing that the present invention provides an arrangement comprising a lifter falling down-preventive cable provided separately from a lifting cable for a lifter and extending along an extended aerial ladder, the intermediate portion of said falling down preventive cable being wrapped a plurality of turns around a drum or pulley means provided on the lifter, said drum or pulley means being provided with brake means and being adapted to be maintained free to turn during normal operation to permit the raising and lowering of the lifter, said brake means being adapted to be manually or automatical actuated to control the rotation or the drum or pulley upon breakage of the lifting cable, so that henceforth the falling down of the lifter is prevented by frictional force exerted between the falling down-preventive cable and the drum or pulley. With this arrangement, it is possible to reliably prevent the falling down of the lifter.

While there have been described herein what are at present considered preferred embodiments of the several features of the invention, it will be obvious to these skilled in the art that modifications and changes may be made without departing from the essence of the invention. It is therefore to be understood that the exemplary embodiments thereof are illustrative and not restrictive of the invention, the scope of which is defined in the appended claims and that all modifications that come within the meaning and range of equivalency of the claims are intended to be included therein .