GB2101189A

GB2101189A - Ladder

Info

Publication number: GB2101189A
Application number: GB08218206A
Authority: GB
Inventors: Livingston Brown
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-06-24
Filing date: 1982-06-23
Publication date: 1983-01-12
Also published as: GB2101189B

Abstract

A ladder in which the rungs 8 are secured to the stiles 26 of the ladder by locating members 27 extending through the stiles into engagement with the rungs and retained against withdrawal and rotation by set screw 30. Also disclosed is an extensible ladder of two or more ladder sections 5, 6 slidable with respect to one another and retained in juxtaposed relation by brackets 10, 11 which inhibit slidable movement in either longitudinal direction until purposely disengaged. A roof ladder incorporating wheels or castors 19 and a cradle 18 engageable over the ridge of a roof are also disclosed. <IMAGE>

Description

SPECIFICATION Ladders This invention reiates to ladders and especially, but not exclusively, to roof ladders.

Conventional ladders suffer from a number of disadvantages. In particular the construction of ladders is generally such that if one of the rungs is broken or damaged and requires replacement it is necessary to take the entire ladder apart which is expensive and time consuming. Moreover the construction of conventional telescopic or extending ladders renders them unsuitable for use as roof ladders since the parts of the ladder disengage when the lower part is not supported on the ground. Consequently previously proposed roof ladders have required to be extremely long and are therefore cumbersome, unmanageable and difficult to store due to their excessive length.

It is an object of the present invention to obviate or mitigate at ieast some of these disadvantages.

According to one aspect of the invention there is provided a ladder in which the rungs are secured to the stiles of the ladder by locating members .extending through the stiles into engagement with the rungs and retained against withdrawal and rotation.

Preferably the locating members comprise tubular pins having flanges at their outer ends and provided with screw threads at their inner ends engageable with complementary threaded end portions of the rungs, means being provided for preventing rotation of the pins relative to the ladder stile. The means for preventing rotation may comprise one or more set screws extending through the flanges and screwed into the associated stiles.

Preferably the inner ends of the pins are externally screw-threaded and the rungs comprise tubular members opposite ends of which are formed with internal screw threads of the same hand engageable with the screw-threaded end portions of the associated pins. The stiles may advantageously be of hollow construction and made from lightweight material such as aluminium to reduce the overall weight of the ladder.

According to a further aspect of the invention there is provided an extensible ladder comprising first and second ladder members slidably movable relative to one another and retained in juxtaposed relation by associated guide members, and means serving to limit lengthwise movement of the respective ladder members relative to one another in either direction until purposely disengaged.

The means to limit lengthwise movement may comprise a pair of oppositely directed hook members provided on each stile of one ladder member and engageable with any selected one of the rungs of the associated ladder member, the hook members being spaced apart to permit engagement with the rung.

The ladder may comprise a roof ladder for which purpose one ladder member is provided at the end which is uppermost in use with a cradle engageable over a roof ridge to retain the ladder in position. Preferably the ladder members are provided with pairs of bearer bars extending parallel and secured at their opposite ends to the ladder stiles.

Preferably two pairs of bearer bars are provided adjacent the opposite ends of the ladder member which is lowermost in use and one pair adjacent the upper end of the ladder member which is uppermost in use. The upper ladder member may also be provided with a pair of wheels projecting therefrom in a direction opposite to the cradle member whereby the ladder may be rolled up the roof on the wheels and then inverted to engage the cradle with the roof ridge.

Preferably the wheels are each mounted as a castor.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a front view of two ladder members engageable with one another to form an extensible ladder according to the invention; Fig. 2 is a side elevation showing the two ladder members in the positions adopted when the ladder is in its shortened position but with the members displaced from one another for purposes of clarity; Fig. 3 is a fragmentary cross-section showing the manner of connection of a rung to a ladder stile; Figs. 4 and 5 are front and side views of the upper end of one of the ladder members; and Figs. 6 and 7 are respectively a side view and a front view, both on an enlarged scale, of an upper end of one of the stiles of a ladder showing the mounting of a castor thereon.

Referring to the drawings, the ladder comprises a main ladder member 5 (referred to hereafter as the lower ladder member) and an auxiliary ladder member 6 which is of greater length but lesser width than the main ladder member so that it may be engaged therewith for relative telescoping movement in known manner. The auxiliary ladder member is referred to hereinafter as the upper ladder member. Each ladder member comprises a pair of parallel stiles 7 interconnected by rungs 8.

The upper end of each stile of the lower ladder member is provided with a guide member 9 which is turned inwardly at its free end so as to embrace the associate stile of the upper ladder member and permit relative longitudinal sliding movement while retaining the ladder members against separation. The lower end of each stile of the upper ladder member is provided with a pair of opposed hook members 10 and 11 which may be engaged over any desired one of the rungs of the lower ladder member, the hook member 10 preventing downward movement of the upper ladder member and the hook member 11 preventing upward movement.The free ends of the hook members are disposed in overlapping relation but displaced from one another to define a gap 12 which is slightly wider than the diameter of the ladder rungs, whereby to permit engagement of the hook assembly with any desired rung dependent on the required overall height of the ladder when extended. Once engaged with the associated rung the hook assembly permits the extended ladder to be pushed up or drawn down from a roof and used as a roof ladder without the ladder members disengaging.

The lower ladder member is provided with upper and lower pairs of bearer bars 1 5 and 1 6 which extend parallel and are secured at their opposite ends to the ladder stiles. The bearer bars are rubber covered and they are adapted to spread the load of the ladder and the user over the roof or the like when the ladder is in use. A similar pair of longitudinally extending bearer bars 1 7 are provided adjacent the upper end of the upper ladder member for a similar purpose.

The upper end of the upper ladder member is provided with a detachable cradle 18 adapted to be hooked over the ridge of a roof to retain the ladder thereon during use. A pair of wheels 19 project from the upper end of the upper ladder in a direction opposite to that of the cradle and in this way the ladder may be rolled up a roof on the wheels and then rotated to hook the cradle over the roof ridge, the wheels then projecting upwardly as shown in Fig. 2. The detachable nature of the cradle permits the ladder to be used as a conventional extending ladder if required.

The cradle 1 8 comprises a pair of side members 1 spa and a pair of reinforcing rails 1 8b which can be gripped by the user, said rails preferably each comprising a bar having an internally threaded bore in each end surface. Bolts 1 sic passing through apertures in the said members secure the bars to the side members by engagement in the threaded bores.

The rungs of the ladder are secured to the stiles in the manner shown in Fig. 3. For this purpose each rung 8 comprises a hollow tubular member of aluminium alloy or other suitable lightweight material the ends of which are provided with internal threaded portions 25. Holes 26 are provided in the side walls of the ladder stile, which is of hollow aluminium alloy or similar construction, and a retaining pin 27 is provided having a flange 28 at its outer end and being externally threaded (at 29) at its inner end. The pin may be passed through the holes 26 and screwed into the adjacent end of the associated rung 8 until the flange abuts the outer surface of the ladder stile. A similar procedure is adopted at the opposite end of the rung and rotation of the pins 27 after assembly is prevented by insertion of a set screw 30.The opposite ends of the rung are threaded to the same hand which, together with provision of the set screw 30, prevents rotation of the rungs relative to the stiles during use.

By constructing the ladder in this manner individual rungs may be removed by withdrawing the set screws 30 and rotating the pins 27 until they are clear of the opposite ends of the rung 8 which may then be replaced and secured in position using the same pins or replacement pins in the event of the latter having been damaged. It is not necessary to dismantle the entire ladder and repairs may therefore be effected simply and cheaply.

The castor arrangement shown in Figs. 6 and 7 is an alternative to each of the wheels 19, giving, in use, more manageable positioning of the ladder on a roof. The arrangement comprises a wheel 31 attached by means of a bolt 33 to an end region of a castor arm 35 which has at its other end a shoulder 37 and an externally threaded portion 39. The portion 39 is received through holes provided in the stile 7 of the ladder and is secured to the stile 7 by a nut 41. The castor arm 35 is able to rotate relative to the stile, a lock nut being provided to prevent loosening of the nut 41, if required.

By virtue of the arrangement described there is provided a ladder in which rung replacement is facilitated and an extensible ladder may be used as a roof ladder due to the construction of the hook assembly which prevents relative lengthwise movement of the ladder members in either direction once engaged. There is therefore provided a roof ladder of extending construction which may be collapsed to a relatively compact form for storage purposes and which may be adapted as an ordinary ladder by detaching the roof ridge cradle. The user's weight is also distributed over the roof despite the telescopic construction of the ladder by provision of the longitudinally extending bearer bars.

Various modifications may be made without departing from the invention. For example the rung fixing arrangement described could be applied to conventional ladders of rigid or extensible construction and the hook assembly may be applied to roof ladders of otherwise conventional construction. An alternative means of retaining the ladder members against displacement in either direction may be adopted.

The bearer bars may be solid or tubular in construction. The bearer bars and wheel arrangement could also be omitted in certain circumstances if desired.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to whether or not particular emphasis has been placed thereon.

Claims

1. A ladder in which the rungs are secured to the stiles of the ladder by locating members extending through the stiles into engagement with the rungs and retained against withdrawal and rotation.

2. A ladder as claimed in claim 1 in which the locating members comprise tubular pins having flanges at their outer ends and provided with screw threads at their inner ends engageable with complementary threaded end portions of the rungs, means being provided for preventing rotation of the pins relative to the ladder stile.

3. A ladder as claimed in claim 2 in which said means for preventing rotation comprises one or more set screws extending through the flanges and screwed into the associated stiles.

4. A ladder as claimed in claim 2 or claim 3 in which the inner ends of the pins are externally screw threaded and the rungs comprise tubular members, opposite ends of which are formed with internal screw threads of the same hand engageable with the screw threaded end portions of the associated pins.

5. A ladder as claimed in any preceding claim in which stiles are of hollow construction and made from lightweight material.

6. A ladder as claimed in claim 5 in which stiles are made from aluminium.

7. A ladder substantially as hereinbefore described with reference to Figs. 1 and 3 of the accompanying drawings.

8. An extensible ladder comprising first and second ladder members slidably movable relative to one another and retained in juxtaposed relation by associated guide members, and means serving to limit lengthwise movement of the respective ladder members relative to one another in either direction until purposely disengaged.

9. An extensible ladder according to claim 8, wherein said means to limit lengthwise movement comprises a pair of oppositely directed hook members provided on end stiles of one ladder member and engageable with any selected one of the rungs of the associated ladder member, the hook members being spaced apart to permit engagement with the rung.

10. An extensible ladder as claimed in claim 8 or 9 for use on a roof in which one ladder member is provided at the end which is uppermost in use with a cradle engageable over a roof ridge to retain the ladder in position.

11. An extensible ladder as claimed in claim 10 in which the upper ladder member is provided with a pair of wheels projecting therefrom in a direction opposite to the cradle member whereby the ladder may be rolled up a roof on the wheels and then inverted to engage the cradle with the roof ridge.

12. An extensible ladder as claimed in claim 11 in which the wheels are each mounted as a castor.

1 3. An extensible ladder as claimed in any of claims 8 to 12 in which the ladder members are provided with pairs of bearer bars extending parallel and secured at their opposite ends to tib ladder stiles.

14. An extensible ladder as claimed in claim 13 in which two pairs of bearer bars are provided adjacent the opposite ends of the ladder member which is lowermost in use and one pair adjacent the upper end of the ladder member which is uppermost in use.

15. A ladder substantially as hereinbefore described with reference to Figs. 1, 2, 4 and 5 or Figs. 1, 2, 6 and 7 of the accompanying drawings.

1 6. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any of the preceding claims.