US3173512A - Ladder levelling device - Google Patents

Description

March 16, 1965 Filed Nov. 19, 1962 2 Sheets-Sheet l FIC-2.2.

March 16, 1965 1 F. sTURDY ETAL 3,173,512

LADDER LEVELLING DEVICE Filed Nov. 19, 1962 2 Sheets-Shea?I 2 United States Patent O 3,173,512 LADDER LEVELLING DEVICE Leonard Frederick Sturdy, Box 240, 2 Grove St.; Hubert Thomas Sturdy, Box 240, 2 Spruce St.; and Kenneth Grant Scott, Box 145, 6 Grove St., all of Massey, 0ntario, Canada Filed Nov. 19, 1962, Ser. No. 238,423 Claims priority, application Canada, June 12, 1962,

4 Claims. (l. 132-202) This invention relates to ladders and more particularly to a means for adjusting the legs of a ladder to compensate for the slope or unevenness of the surface on which the ladder may rest.

A number of devices of this type have been proposed but these have not been entirely satisfactory due to being expensive to manufacture, awkward to use or not completely reliable in operation. It will be appreciated that devices of this type particularly those intended for use on long extension ladders should be completely reliable in Operation to insure the safety of persons working thereon.

It is an object of the present invention to provide a ladder levelling means which is inexpensive t-o manufacture and simple and reliable in operation.

It is a further object of the invention to provide ladder levelling means which is readily adaptable for use on most conventional ladders including extension ladders and step ladders so that it is not essential to modify the con- Ventional ladder to any great extent or to produce a ladder particularly for use with this device.

'I'he present invention provides a ladder levelling device comprising a pair of extension legs adapted to slidably engage opposite side rails of a ladder, clamping means including a cam member and securable to the ladder, a rst flexible member interconnecting the upper portions of said extension legs, a second llexible member interconnecting the lower portions of said extension legs, said rst and second flexible members passing through said clamping means, and said cam member in said clamping means being adapted releasably to engage said flexible members and prevent movement of said llexible members relative to one another and to said clamping means.

In the drawings which illustrates an embodiment of this invention:

FIG. l is a front elevational view of the levelling means of this invention installed on a ladder shown supported on uneven terrain;

FIG. 2 is a sectional front elevational view of part of the ladder and levelling means of FIG. 1;

FIG. 3 is a cross sectional view taken substantially along the line 3 3 of FIG. 2;

FIG. 4 is an enlarged front elevation of the clamping means of FIG. l;

FIG. 5 is a cross sectional view taken along the line 5 5 of FIG. 1; and

FIG. 6 is a perspective view of the extension legs of the levelling means of FIG. 1.

Referring now in detail to the drawing in which the levelling device shown generally at 1t) in FIG. 1 is shown installed on the lower portion of a ladder shown generally at 11 supported by uneven ground 12.

The ladder 11 is of conventional construction and comprises side rails 13 and 14 which are connected by rungs 15.

The levelling device comprises a pair of extension legs 16 adapted to slide longitudinally on the side rails 13 and 14 of the ladder 11. Each of the extension legs 16 are formed in the shape of a tube having a substantially rectangular cross section and a longitudinally extending slot 17, see FIGS. 3 and 6. The width of the 3,173,512 Patented Mar. 16, 1965 slot 17 is slightly greater than the diameter of the rungs 15. The side of each extension leg 16 opposite the slot 17 is provided with a longitudinally extending outwardly bent portion defining a channel 18 the purpose of which will be explained below.

A clamping mechanism 19, shown in FIGS. 4 and 5, is secured to a lower rung 15 of the ladder 11 and comprises a pair of plates 20 each plate having a curved rung engaging portion 21 at one end thereof. A spacer element 22 is provided between the plates 20 adjacent the rung engaging portions 21, being secured as by welding to one of the plates 20. An eccentric cam member 23 and its associated operating lever 24 is rotatably secured between the plates 20 by a bolt 25 passing through the cam 23 and the plates 20, the arrangement being such that there is a gap between the edge of the cam 23 and the spacer element 22. The cam has such dimensions and is so mounted with respect to the spaced element 22 that movement of the operating lever 24 to the right as indicated in FIG. 4 tends to almost close the gap between the edge of the cam and the spacer element 22; movement of the operating lever 24 in the reverse direction tends to increase the width of this gap. A second bolt 25 passing through suitable apertures in the plates 20 urges the rung engaging portions 21 of the plates 20 into gripping engagement with the rung 15.

A flexible member such as a length of cable 26 is secured by bolts 30 to the upper end of the extension leg 16 on the side rail 13. The cable 26 passes downwardly between the side rail 13 and the inside of the extension leg 16 in the channel 18 described above and shown most clearly in FIG. 3. A pair of mutually opposed apertures 27 bored in the side rails 13 and 14 of the ladder below the lower rung 15 are provided with bushings 28 shown most clearly in FIG. 2. Inward movement of the bushing 28 is prevented by integral flange 29 thereon.

The cable 26 passes through the bushing 28 in the side rail 13, then through the clamping mechanism 19 between the spacer element 22 and the cam member 23, then through the bushing 28 in the side rail 14, and then upwardly through the channel 18 in the extension leg 16 on the side rail 14. A bolt 30 secures the end of the cable 26 to the upper end of the extension leg 16 on the side rail 14.

Similarly, a second flexible member such as a cable 31 is connected by a bolt 30a to the lower end of the extension leg 16 on the side rail 13. The cable 31 passes between the side rail 13 and the extension leg 16 in channel 18, then through the bushing 28 in the side rail 13, then through the clamping mechanism 19, then through the bushing 28 in the side rail 14, and then through the channel 18 in the extension leg 16 on the side rail 14. The end of the cable 31 is secured by the bolt 30a to the lower end of the extension leg 16 on the side rail 14. Be-

tween the bushings 28 the cables 26 and 31 lie parallel and closely adjacent to one another. The cables 26 and 31 are of such length that little if any slack is left in the cables when they are installed as described above.

As will be apparent from the drawings, when the ladder 11 provided with the device 10 is set up on sloping ground 12, the clamping mechanism 19 being in the inoperative position, the extension legs 16 move 1ongitudinally on the side rails of the ladder to support the ladder in the desired position as illustrated in FIG. l. As the extension legs 16 move to the desired position there is corresponding movement of the two cables 26 and 31. The bushings 28 prevent the cables from causing undue wear at the points where the cables pass through the side rails 13 and 14 of the ladder.

Downward movement of extension leg 16 on side rail 14 causes cable 26 to move to the left as viewed in FIG. 1 and upward movement of the extension leg 16 associated with side rail 13 causes the portion of cable'26 so displaced to be taken up. The relative movement ofY cable 31 is the reverse of that described above 1n con-4 nection with cable 26. n n .Y

The extension legs 16 are locked in the desired YpositionV by moving the operating lever 24 of the clamping 'mechanism 23 so that the'ecoentriccam member 23. is brought vinto firm contact with the cables 26 and 51r thereby pressing them into frictional engagement with the spacer element 22. The ladder 11 remains supported in therdesired position by the extension legs 16 vuntil the userV moves the ladder to a new location where a different arthe lower portions of said yextension legs, said rst and second flexible members passing through said clamping means, and ysaid circular disc in said clamping means being adapted to engage said flexible members and prevent movement of said flexible members relative to one another and to said clamping means' unless said clamping means is manually released. Y

' 3. A ladderc'omp'rising va pair of opposed side rails,

rangement of the extension legs 16 is required. It is then necessary to release the clamping mechanism to allow the extension legs to adjust to the terrain in that location and then to bring the clamping mechanism into operation again. y J

It is understood that the specilicr embodiment described above is simply illustrative' of the 'principles of the 1nvention andv that the various modifications which will occur to those 'skilled in the art willY fall' within the 'spiri and scope of the invention.

For example it is possible to modify fthe A'arrangement i of the cables 26 and 31 showniin FIG. 1 so that the cables would be on the exterior of the extension legs 16. The cables would then pass through suitable brackets secured to the ladder rather Vthanpassing thourgh apertures 27 in the side rails of the ladder as described above.V

We claim: I. 1. A ladder levelling device comprising a pair of extension legs adapted slidably toVv engage opposite side:

rails of a ladder, manually operable clamping means drirectly and vfixedly securable to said ladder, said clampingV means including 4a pair of plates, a portion of'each said plate being shaped so,A that said plates co-operate' to -embrace a ladder rung therebetween, a (cam, member pivotally secured,v between said plates, a iirst exible member interconnecting the upper portions of said extension legs, a second flexible member interconnecting the lower portions of said extension legs, said iirst and second iiexible members passing'through said clamping means,and said cam member in said clamping means being adapted 'to' engage said flexible members and prevent movement Yor Vsaid ilexible members relative to` one another and to said clamping means .unless'said Vclamping means is manually released.

2. A nader levelling' device eomprising av pair (5f-en tension legs adapted slidably to vengage oppositeside railsv of a ladder, manually operable clamping means securablefA 50 to said ladder, said clamping means including arpair of;

plates, aportion of each said plate beingr shaped so thatA said plates co-operate to embrace` a ladder rung therebetween, meansfto urge said portions. of said plates to-j gether to lixedly secure said clamping means to said rung,

a circular disc including handlerneans, said disc beingA eccentrically mounted between saidl plates, a first ilexibleY member interconnecting the upper portions of said ex-A tension legs, a second iiexible member interconnecting4 rungs between said side rails, Va'paijr, of extending legs Yadapted slidably to engage said siderails, manually operableY clamping meansfixedly secured to said ladder, said clamping means including a pair of plates, a portion of each said plate being shaped sothat said plates cio-'operate to embrace one of said rungstherebetween, arca'm inember pivotally secured between said plates, a iirstiiexible member interconnecting the upper portions of said yeirtension legs, v.said first flexible member passingthrough one of saidrside'rails, saiddclainping means and the other.

' of said side rails; `a second flexible member interconnecting-.the lower portion of said'extension legs, said second flexlble member passing through one yof said side rails, said clamping-means and the otherof said side rails, and a cammember in said clamping means, said cam member being adapted to `engage said iiexible members and prevent movement` of V*said liexible`v members relative to one another and to said clampingmeaus unless said clamping 7 means is manuallyl released.`

4, A'laddereomprising aV pair of opposed side rails,

rungs between said side,rai1s', ay pairof extension legs adapted slidably to engagev said side rails, manually operable clamping means xedly secured to a selected one of said rungs, said clamping means including a pair of Y, plates a port-ionof each said-.plate being shaped so that Y said plates co-operatev to engage said rung therebetween,

means to urge said portions of said plates together, a circular disc-including handle means, said disc being eccentrically mounted between said plates, a first liexible member 1nterconnecting theiupper portions of said extension legs, said rst exible. member 'passing through one of said siderails, said clampingr means andthe Yother of said Y Vsiderails; a second flexibler member interconnecting the lower .portions of said extensionlegs, and second` ex- 1ble member passing through one of said side vrails,.said

Y'clamping means and the. other of said side rails, saidv disc in` said, clamping means`,1fbeing'adapted to engage said .Y flexible members andV prevent movement of said llexible members. relative toV oneanother andto: said clamping means untirlzsaid clampinglmeans is-'manually released.

Claims (1)

1. A LADDER LEVELLING DEVICE COMPRISING A PAIR OF EXTENSION LEGS ADAPTED SLIDABLY TO ENGAGE OPPOSITE SIDE RAILS OF A LADDER, MANUALLY OPERABLE CLAMPING MEANS DIRECTLY AND FIXEDLY SECURABLE TO SAID LADDER, SAID CLAMPING MEANS INCLUDING A PAIR OF PLATES, A PORTION OF EACH SAID PLATE BEING SHAPED SO THAT SAID PLATES CO-OPERATE TO EMBRACE A LADDER RUNG THEREBETWEEN, A CAM MEMBER PIVOTALLY SECURED BETWEEN SAID PLATES, A FIRST FLEXIBLE MEMBER INTERCONNECTING THE UPPER PORTIONS OF SAID EXTENSION LEGS, A SECOND FLEXIBLE MEMBER INTERCONNECTING THE LOWER PORTIONS OF SAID EXTENSION LEGS, SAID FIRST AND SECOND FLEXIBLE MEMBERS PASSING THROUGH SAID CLAMPING MEANS, AND SAID CAM MEMBER IN SAID CLAMPING MEANS BEING ADAPTED TO ENGAGE SAID FLEXIBLE MEMBERS AND PREVENT MOVEMENT OF SAID FLEXIBLE MEMBERS RELATIVE TO ONE ANOTHER AND TO SAID CLAMPING MEANS UNLESS SAID CLAMPING MEANS IS MANUALLY RELEASED.

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