GB2191532A - Loft ladder - Google Patents

Abstract

A loft ladder which consists of a ladder, or a number of ladder sections (11 and 12) slidably mounted upon each other, and means for connecting the upper end of the ladder, or uppermost ladder section (11), to one margin (13) of a loft aperture (14) in such a way as to permit sliding and pivotal movement relative to the aperture (14), wherein each stile of the ladder or uppermost ladder section (11), is formed with inwardly directed longitudinal flanges and the connecting means includes an insert (16) fitted between the flanges so as to be captive therebetween but capable of longitudinal relative sliding movement and extending (as at 23) outwardly to a pivot, and wherein the insert (16) is provided with a recess (17) defining a cam surface (19) for co-operation with a cam member (18) located in the recess (17), the arrangement being such that during upward movement of the ladder or section (11) relative to the insert (16) the cam member (18) is urged to an inoperative position to permit free upward movement of the ladder or section (11), but during downward movement of the ladder or section (11) relative to the insert the cam member (18) is urged to an operative position in which further downward movement of the ladder or section (11) is inhibited. <IMAGE>

Description

SPECIFICATION Loft ladders This invention relates to loft ladders intended to be mounted in the trap door aperture of a loft, and consisting of a ladder, or a number of ladder sections slidably mounted upon each other, and means for connecting the upper end of the ladder or uppermost ladder section to one margin of the aperture in such a way as to permit sliding and pivotal movement relative to the aperture so that the ladder or sections can be stored away when not required for use by pushing the ladder or sections upwardly relative to the connecting means and then rotating the ladder or sections into the loft space.

It is an object of the present invention to provide an improved loft ladder which is simple in construction and operation and which is safe in use.

The present invention consists in a loft ladder which consists of a ladder, or a number of ladder sections slidably mounted upon each other, and means for connecting the upper end of the ladder, or uppermost ladder section, to one margin of a loft aperture in such away as to permit sliding and pivotal movement relative to the aperture, wherein each stile of the ladder or section, is formed with inwardly directed longitudinal flanges forming channels and the connecting means includes an insert fitted between the flanges of both adjacent stiles so as to be captive therebetween but capable of longitudinal relative sliding movement and extending outwardly to a pivot, and wherein the insert is provided with a recess defining a cam surface for co-operation with a cam member located in the recess, the arrangement being such that during upward movement of the ladder or section relative to the insert the cam member is urged to an inoperative position to permit free upward movement of the ladder or section, but during downward relative movement of the ladder or section the cam member is urged to an operative position in which further downward movement of the ladder or section is inhibited.

In the accompanying drawings:- Figure 1 is a general view of one form of loft ladder according to the present invention shown in its opened position ready for use, Figure 2 shows, in part longitudinal section on an enlarged scale, a detail of the interconnection between the two ladder sections, Figure 3 is a cross-section taken on line 3--3 of Figure 2, Figure 4 is a cross-section taken on line 4--4 of Figure 2, Figure 5 is a detail of a modified form, partly cut away, showing the interconnection of the two ladder sections, Figure 6 is an exploded detail of a modified form showing the components of the interconnection between the upper ladder section and the loft aperture, and Figure 7 shows an alternative form of insert for use in a loft ladder according to the present invention.

In carrying the invention into effect according to one convenient made by way of example, figure 1 shows one form of loft ladder according to the present invention in its opened or extended position ready for use.

The ladder includes two ladder sections 11 and 12 composed of aluminium alloy, the upper end of the upper section 11 being connected to the margin 13 of a loft opening 14 by means of a hinge 15.

The adjacent parts of the stiles of the two ladder sections 11 and 12 are formed so as to be of rectangular C-shape channel in cross-section as will be seen from figures 3 and 4, and the channels of each adjacent pair of stiles are interconnected by means of an insert 16, composed of plastics material, which is I-shaped in cross-section and fits the two C-shaped channels.

The two sections are thus held together by the inserts, but relative movement between the sections can take place.

Each insert 16 has a cut-away portion 17 to provide a recess in which is trapped a cam member in the form of a roller 18 and having a cam surface 19 co-operating with the roller 18. The insert is also cut away at 20 to give flexibility to that part 21 between its two ends. The insert 16 is immovably fixed to the ladder section on the side away from the roller 18, i.e. to the upper ladder section 11 at the lower end of the stile. A similar plastic insert, Ishaped in cross-section but lacking the cut-away recess is immovably fixed into the co-operating lower ladder section 12 at the upper end of each stile to act as a guide to ensure the sections slide squarely in relation to each other. As the ladder is extended, the inserts fixed in each section eventually come together, thus also acting as stops at the point of maximum extension.

When the roller 18 is in the position shown in Figure 2, i.e. above the restriction in the recess 17 produced by the shape of the cam surface 19, the camming action of the roller 18 on the surface 19 will hold the ladder section 12 against gravity and prevent it from falling downwardly, but the section 12 can be freely raised to any higher level at which it will again be held against gravity.

However, if the section 12 is pulled firmly downwardly the roller 18 will be rotated in a clockwise direction causing it to be rolled through the restriction with a snap or ciick action, the roller falling to the bottom of the recess 17 as shown in dashed lines at 22.

In this, its lower position, the roller will no longer prevent downward movement relative to section 11 of the section 12 which thus may be lowered freely.

When the section 12 is next raised relative to section 11, the roller 18 will be rolled back through the restriction in the reverse direction until it has returned to the position shown in figure 2.

Thus, in summary, by forcible movement of ladder section 12 relative to section 11 in the appropriate direction, the roller 18 may be moved with a snap or click action between its upper and lower positions. When in the upper position, the roller 18 permits free relative upward movement of section 12 but holds it against gravity, and when in the lower position the roller 18 allows free downward movement but upward movement of sufficient force will cause the rollerto be returned to its upper position.

At the top of the upper section 11 a similar insert is provided between a C-shaped channel formation on the stile of section 11 and a T-shaped formation on a member 23 pivotably connected to a bracket 24 secured to the margin 13 of the loft openings, and a similar effect on the relative movement between the upper section 12 and the member 23 is provided as between section 11 and 12 described above. Stops are provided at the upper end of the stiles of the upper section 11 to limit its downward movement and at the lower end to limit upward movement.

Assuming, that the rollers 18 are in their upper positions, then starting from the position shown in figure 1 the ladder may be closed first by raising section 12 until it overlies section 11 and then by pushing the two sections together into the loft space rotating them about the hinge 15 when they have been raisad sufficientlyfarto clear the opening 14. If at any stage during this process either section is released it will be held against gravity in the manner previousiy described.

When the ladder is next required for use, the two sections 11 and 12 are first rotated in the reverse direction out of the loft space, and then pulled sufficiently hard to cause the clamping effect of the rollers 18 to be overcome. If the clamping effect between the two sections is made somewhat stronger than that between the upper section 11 and the member 23, then the clamping between the section 11 at the member 23 will be overcome first, regardless of which ladder section is pulled enabling the two sections to be lowered in unison before the lower section 12 is lowered relative to upper section 11.

Figure 7 shows an alternative construction in which the cam surface is inclined but does not have a restriction through which the roller can pass. The arrangement is such that when the lower section is moved upwardly, the roller is urged into an inoperative position to permit free upward movement of the section, but when the lower section is moved firmly downwards the roller is moved into an operative jamming position in which the weight of the section is held against gravity, although the section can be lowered slowly without the jamming action occurring.

If desired, this form of insert can be used also between the upper section and the hinge.

Claims (8)

1. A loft ladder which consists of a ladder, or a number of ladder sections slidably mounted upon each other, and means for connecting the upper end of the ladder, or uppermost ladder section, to one margin of a loft aperture in such a way as to permit sliding and pivotal movement relative to the aperture, wherein each stile of the ladder or uppermost ladder section, is formed with inwardly directed longitudinal flanges and the connecting means includes an insert fitted between the flanges so as to be captive therebetween but capable of longitudinal relative sliding movement and extending outwardly to a pivot, and wherein the insert is provided with a recess defining a cam surface for co-operation with a cam member located in the recess, the arrangement being such that during upward movement of the ladder or section relative to the insert the cam member is urged to an inoperative position to permit free upward movement of the ladder or section, but during downward movement of the ladder or section to the insert the cam member is urged to an operative position in which further downward movement of the ladder or section is inhibited.

2. A loft ladder as claimed in claim 1, wherein a number of ladder sections are provided and the adjacent stiles or adjacent ladder sections are formed with inwardly directed longitudinal flanges, adjacent ladder sections being joined together by means of an insert fitted between the flanges of both adjacent stiles so as to be captive therebetween but permitting longitudinal relative sliding movement between the two adjacent ladder sections, the insert being fixed to one of the two adjacent ladder sections.

3. A loft ladder as claimed in claim 2, wherein the insert is I-shaped in cross-section.

4. A loft ladder as claimed in claim 1,2 or 3, wherein the cam surface is shaped to provide a restriction in the recess through which the cam member may be forced by relative movement between the insert and the flanges in which it is captive, the arrangement being such that, in use, when the cam member is above the restriction the cam member will permit free relative upward movement of the ladder or section butwill hold it against gravity, and when the cam member is beiow the restriction the cam member will allow free downward movement of the ladder or section but will be forced above the restriction upon upward movement of sufficient force of the ladder or section.

5. A loft ladder as claimed in claims 1, 2, and 4, wherein the force required to move the cam member from above the restriction to below the restriction is less for the insert connected to the pivot than for the insert or inserts between adjacent ladder sections.

6. A loft ladder as claimed in claim 1,2 or 3, wherein the cam surface is inclined and shaped to co-operate with the cam member such that when the ladder or section is moved upwardly the cam member is urged into an inoperative position to permit free upward movement of the ladder or section, but when the ladder in section is moved firmly downwards the cam member is moved into an operative jamming position in which the weight of the ladder or section is held against gravity, although the ladder or section can be lowered slowly without the jamming action occurring.

7. A loft ladder as claimed in any one of the preceding claims, wherein the cam member is in the form of a roller.

8. A loft ladder substantially as described with reference to the accompanying drawings.