US2797038A - Extension ladder with hook type fastening - Google Patents

Description

June 25, 1957 Filed April 20, 1956 E. TIBERGHIEN EXTENSION LADDER WITH HOOK TYPE FASTENING 2 Sheets-Sheet I.

June 2 5, 1957 E- TIBERGHIEN Filed A ril 20. 1956 EXTENSION LADDER WITH HOOK TYPE FASTENING 2 Sheets-Sheet 2 EXTENSION LADDER WITH HOOK TYPE FASTENING Etienne Tiberghien, Tourcoing, France, assignor to Socit Metrostatie S. A., Tangiers, Morocco, a corporation of Tangiers Application April20, 1956, Serial No. 579,515

Claims priority, application France April 22, 1955 3 Claims. (Cl. 228--66) My invention relates to sliding ladders having two or more sections and has for its object to provide a novel hook fitting between the sections, for inclusion in the construction of such ladders.

Known sliding ladders at present utilise for the connection of two sections the one wit-h respect to-the other, a stop device known .as a rocker. Thisrocker is constituted by a locking member pivoted between the two sides of the larger of the two sections in question, which rocker, in the position of use, supports the smaller of the two sections by engaging one of the rungs of this small section. The disengagement of the rocker fromthe rungs of the small section, to cause this latter to descend withrespect to. the large section, is eifectedby giving the operating: rope a suitable inclination. This operation is delicate andoften dangerous.

This type of rocker has various drawbacks. On. the onerhand. the buildingof the ladder presents difficulties as the mounting imposition of the rocker weakens the sides of .the ladder which must carry the spindles for the rocker, further therocker is rather heavy and, finally, replacement of therocker necessitates a complete dismantling of theladder.

Sliding. ladders of the American type are also known. Theseladders comprise fittings constituted by an anchoring member and a release. bolt arranged in such'manner that, during raising, they automatically engage by their own weight on the successive rungs of the stationary section whilst, in'ordento disengage the ladder and to lower it, it is sufficient to raise the movable section by about half the spacing between two rungs so that the auxiliary bolt of the fitting engages with the rungs and releases the anchoring member from the successive rungs.

In these so-called American type ladders, the small or sliding section of the ladder is located on the upper side of the large section whereas according to French technique the positions of the sections are reversed.

My invention concerns a fitting derived from the said fitting having an anchoring member and a release bolt which permits the construction of sliding ladders with the movable section located on the under side of the stationary section.

The fitting according to the present invention is formed by a stirrup to be fixed on the movable section of the ladder, this stirrup carrying a spindle on which is mounted to rotate a member having the shape of a comma, the axis of articulation being such that it divides this member into a small arm directed towards the front of the movable section and which constituted the hook for engaging the rungs of the stationary section, and a large arm directed towards the rear, a release bolt, formed by an L piece, being mounted at the extremity of this large arm in such manner that it can turn through a desired angle, so that it is able either to come in the prolongation of this large arm, or to come to bear against the extremity of the small arm to form a closed perimeter, and it is characterised in that the stirrup has a sleeve for mounting on one of the fixed rungs of the movable section of the ladder,

atent ice the member in the shape of a comma being such that when it is. itself supported by its short arm on one ofthe rungs of the stationary section it also bears on the stirrup mounting rung and exerts on this latter a force tending to hold the movable section pressed against the stationary section.

In order that the invention may be better understood, it will now be described with reference to the accompanying drawings in which:

Fig. 1 is a perspective view of a fittingaccording to the invention.

Fig. 2 is a view in partialsection of this fitting in use moving in the ascending direction and passing over a rung of the stationary section.

Fig. 3 is a view. corresponding to Fig. 2 with the fitting inengaging position on a rung of the stationary section.

Fig. 4 is a view corresponding to Fig. 2 showing the fittingstill ascending after passing over a rung of the stationary section.

Fig. 5"is a view corresponding to Fig. 2 showing the fitting .passingover a rung ofth'e stationary section during the lowering movement.

Fig. 6 is a diagrammatic view of'a ladder having three sections showing the disposition of the fittings and ropes in such a ladder.

The fitting represented in Fig. 1 comprises a stirrup 3 having a sleeve 1 and a bore 2 in the sides thereof, the sleeve 1 being fixed on the side of the stirrup which faces towards the inside of the ladder. This stirrup is to be mounted on the rung 4 (shown in position, ready for mounting). It has a spacing reinforcement 5, and at its upper part a lateral lug 6 with an aperture for the passage of a screw or bolt for fixing the stirrup in position. In the sides of the stirrup and at the upper part of this ladder is provided a bore 8 for the engagement of a spindle 9, this spindle being such that it comes flush with the face of the stirrup directed towards the side 10 of the ladder. in order not to penetrate into this ladder and not to weaken for this reason the strength of the said side. This spindle preferably has towards its head 11 a threaded portion 12 to cooperate with a correspondingthread provided in the bore 8 of the side of. the stirrup 3 directed towards the centre of the ladder.

On this spindle 9 is pivoted a member 13 having the shape of a comma. This member 13 has a small arm 14 directed towards the front of the movable section with respect to the stirrup 3, which small arm has at 15 on its under surface a recess the shape of which corresponds to the cross section of a rung in the stationary section of the ladder. The large arm has in a similar manner at 16 a recess adapted to bear against the back and beneath the rung 4 on which the stirrup 3 is mounted by means of the sleeve 1 and bore 2. At the free extremity of the large arm is formed a fork 17 in which are provided two apertures for a spindle 18 ensuring the mounting for partial rotation of the member forming the bolt 19. This member is constituted by a body with a lug 20 on its inner face, having a bore for the passage of the spindle 18.

The fitting, as shown in the drawings, is mounted on the lower rung 4 of the movable section or sections and this fitting is designated, in Fig. 6, by the reference numeral 21. A second similar but handed fitting symmetrical with respect to the axis of the section is also mounted on the same rung and applied against the second side of the ladder. In the position of rest shown in Fig. 4, the small arm 14 projects, on the front of the movable section on which it is mounted, sufficiently to come beyond the median plane of the rungs 4' of the stationary section.

When the ladder is raised, and as shown in Fig. 2, the projecting portion of the small arm 14 is pushed bacls upon passing by the rung which then comes opposite the fitting and the fitting'takes the position shown in Fig. 2. Once the fitting has passed'the rung, it takes its position ofrest, that is, the position shown in Fig. ,4 and if, at this moment, the movable section is allowed -to descend, the extremity of the arm 14 co-operating with the rung 4' causes the fitting to rock in a clockwise direction. The fitting then comes into the position shown in Fig. 3, connecting the rungs 4 and 4 and efiecting the engagement of the movable section with the stationary section.

On the contrary, if the lowering movement is begun whilst the extremity of the release bolt 19 is located above the rung 4', this, bolt, cooperating with'the rung 4, pivots around the spindle 18ina clockwise direction and closes what can be considered as the opening of'the fitting as shown in Fig. The movable'section will then be able to 'slide down under the stationary section without engagement of the fitting with the rungs ,4.

In Fig. ,6 there has been shown diagrammatically in section a ladder having three sections, the sections being shown separated for clearness.

' The section 22 is the stationary section, the section 23 is the-movable intermediate section and the section 24 the movable small or third section.

Two fittings 21 such as described are mounted on the lower rung of each of the sections 23 and 24.

A pulley 25 is mounted, by its strap, on the upper rung of the section 22 and a pulley 26'0n the lower rung of the section 23, these two pulleys forming the tackle for the single operating rope 27.

Theoperation of the third section is ensured by a rope 28 which is engaged at one of its extremities with the upper rung of the section 22 and passes over a pulley 29 the strap of which is mounted on the upper rung of the section 23 and the other extremity of which is engaged with the lower rung of the section 24. This rope includes in its length an adjuster 30 for regulating the length thereof so that the sections move proportionately and to ensure an accurate operation of the complete assembly.

It should be observed that what normally would be the lower rung of the movable sections is not fitted, but the position therefor left blank, to avoid the danger presented by a rung in this position when the ladder is in use.

The invention is not limited to the precise forms or details of construction herein described, as these may be varied to suit particular requirements.

What I claim is:

l. A fitting for sliding ladders having two or more sections, comprising a stirrup to be fixed on the movable section of the ladder, thisstirrup carrying a spindle on which is mounted to rotate a member having the shape of a comma, the axis of articulation being such that it divides this member into a small arm directed towards the front of the movable section and which constitutes the hook for engaging the rungs of the stationary section, and a large arm directed towards the rear, 21 release bolt formed by an L piece being mounted at the extremity of this large arm in such manner that it can turn through a desired angle so that it is able either to come in the prolongation of this large arm or to come to bear against the extremity of the small arm to form a closed perimeter, the stirrup having a sleeve for mounting on one of the fixed rungs of the movable section of the ladder, the member of comma shape being such that when it is itself supported by its short arm on one of the rungs of the stationary section it also bears on the stirrup mounting rung and exerts on this latter a force tending to hold the movable section pressed against the stationary section.

2. A fitting as claimed in claim 1 in which one side of the stirrup when mounted in position is adapted to come flat against the inner surface of one side of the ladder and which side of the stirrup has an apertured lug adapted to be held by screw means in position against this side of the ladder, and further in which the dimensions of the parts are such that in the position of rest the member of comma shape with the release bolt pivoted thereto hangs so that the short arm of said comma-shaped member projects on the front of the movable section sutficiently to come beyond the median plane of the rungs of the stationary section when in position against the movable section.

3. Fittings for sliding ladders as claimed in claim 1 in which the stirrups are formed handed, one, of one 'side member of the ladder so that the short arms of the comma-shaped members of each fitting project forwardly from the movable section to engage the rungs of the fixed section.

No references cited.

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