PORTABLE LADDER ESPECIALLY SUITED FOR SLOPES AND UNEVEN GROUND .

DESCRIPTION Fjeld of h invention

The present invention relates to a portable ladder especially suited for slopes and uneven ground and therefore particularly intended for the agriculture field — for example, for pruning and harvesting of fruit — but which can also be used in general for domestic work and by anyone who make use of ladders in his profession — for example, in the field of construction, for any maintenance work, in industry and so on . Description of the prior art

The conventional portable ladder has many well- known drawbacks. First of all, it does not easily adapt to sloping or uneven ground and it is difficult in such conditions to find a stable supporting position, so that the operator must climb and move very carefully on the ladder, since even small movements may throw the ladder out of balance and in danger of falling. Second, it does not offer any guarantee of stability in case the support of one of the two stanchions gives way: also in this case the sudden displacement from the equilibrium position may result in the fall of the operator. Moreover, it is often difficult to find a stable support for the upper end of the ladder, especially on trees, and, among other difficulties, the upper end is sometimes too large compared with the available space among the branches and thus provokes with its movement the breaking of small branches or buds or the falling of fruit.

A supporting base for portable ladders on which the lower ends of the stanchions may be fitted or fixed is also well known . This base, being considerably wider than the ladder, certainly increases the stability of it on even and firm ground, but does not by any means solve the above- mentioned problems.

Summary of the invention

The purpose of the present invention is to make available a portable ladder that can easily adapt to various types of uneven ground while maintaining a vertical posture even if one of the supports on the ground gives way.

Another purpose of the present invention is to make available a portable ladder of the above mentioned type for which, within ample margins, the operator's movements do not affect the stability of the ladder itself.

A further purpose of the present invention is to make available a portable ladder of the above mentioned type for which the upper end can be supported at just one point, even on branches sloping down and far from the central trunk, so as to avoid damage to fruits, buds or foliage without compromising the stability of the ladder itself.

All these purposes are achieved by the portable ladder according to the present invention, which is of the kind that comprises a number of parallel rungs fitted on two handrail stanchions and characterized by being connected pivotally to a supporting base about an axis that is orthogonal to the plane in which the ladder lies and that meets the longitudinal symmetry axis of the ladder. In this way the ladder can be angularly displaced in

said plane in order to keep said symmetry axis vertical regardless of the sloping of the supporting plane of the base .

In a particularly preferred embodiment of the invention the parallel rungs are fitted to a central stanchion that is hinged to the supporting base. To the free end of the central stanchion an element for support against a structure located at a certain height — such as a branch, a pole, a wall or so forth — can be attached.

In a possible embodiment of the invention, particularly suited for professional use of the portable ladder, a device for locking the ladder in a chosen inclined position can be provided for at the hinge on the supporting base.

Brief description of the drawings

Further characteristics and advantages of the portable ladder according to the present invention will be clearer from the following description of one of its embodiments, which is to be intended only as an example and not a limitation, referring to the attached drawings, in which:

Fig. 1 is an elevational front view of the ladder according to the invention; - Fig. 2 is an enlarged view of the articulated joint between the ladder and its supporting base;

Fig. 3 is an enlarged view of a different embodiment of the device of fig. 2;

- Figs. 4 and 5 are, respectively, a front and a side view of the articulated joint on the supporting base provided with a first type of locking device;

Fig. 6 is a front view of the articulated joint on the supporting base with a second type of locking device;

Fig. 7 is a perspective view of a possible system for fitting the ends of the ladder's stanchions to a supporting base according to the invention; - Fig. 8 is a perspective view of the upper end of the ladder according to the invention provided with a supporting tip.

Description of preferred emborH ment-.g Referring to Fig. 1, a vertical rod is indicated with 1, to which a number of horizontal rungs 2 are connected, equally spaced and fitted laterally to a pair of handrail stanchions 3. Vertical rod 1 is connected to a supporting base 4 at one of its ends la, which is hinged at the point 5 in the middle of the supporting base. The axis of articulated joint 5 is orthogonal to the plane in which the ladder lies and intersects its longitudinal symmetry axis, which coincides with vertical rod 1. Supporting base 4 comprises a transversal rod 4a and a pair of supporting feet 6 located in a plane that coincides with the plane of the ladder, and it further comprises stabilizing elements 7, such as wedges, located near said feet and suited to be embedded in the ground below, indicated with T.

The free end of vertical rod 1 is provided with a supporting element 8 practically shaped as a fork projecting outward — that is, toward the back of the ladder — which can stabilize the ladder with respect to a supporting structure located at some height, such as a branch R. In the same figure a possible extension 9 of supporting fork 8 is also sketched with a dashed line; it can slide inside rod 1 by means of an internal sliding device of any known

- 5 - type and not shown, controlled by a crank 10 situated about a meter from the ground.

As shown in Fig. 1, even if the ground T is sloping at an angle g with respect to the horizon, thanks to the articulated joint fitted on supporting base 4, the ladder can be maintained vertical and its position can be made stable by adjusting supporting element 8 in a suited position against a supporting structure, such as, for example, into a bend or fork of a branch, around a trunk or pole or an ascending or descending branch, or in other positions that may become available when needed, such as to avoid lateral sliding of supporting element 8. Thus, since the weight of the ladder and of the operator on top of it press down on articulated joint 5, the ladder itself becomes completely stable. It should also be noticed that, even in case the ground under one of feet 6 should give way, the ladder, being held in its upper end by supporting element 8, can rotate around joint 5 as much as necessary to stay vertical. Without the articulated joint, as with a conventional ladder, a lateral movement or a rotation about the stanchion whose foot is giving way may occur, both of which may cause the fall of the operator.

Fig. 2 shows in more detail the construction of the articulated joint between the ladder and supporting base 4. The latter has a fin 11 in its center projecting from transversal rod 4a and lying in the same plane as feet 6, and this fin 11 fits between a pair of fins 12 extending from the lower end of rod 1. Fin 11 and fin pair 12 are connected by a pivot 13 orthogonal to said plane.

In the embodiment shown in Fig. 3 the ladder is rigidly connected to a transversal rod 14 by means of its side stanchions 3. Fin 11 integral to base 4 engages between fin pair 12 extending from transversal rod 14. Also in this case pivot 13 connects fins 11 and 12, thus implementing the articulated joint between the ladder and its supporting base.

The articulated joint between the ladder and its base can also allow professional workers to make use of the ladder in an inclined position within its plane, for example, when obstacles prevent the direct alignment of the base and the point to be reached. In such a situation, the articulated joint can be provided with a locking device that can be applied to stabilize the ladder in the particular inclined position selected as suitable for the situation. Several different kinds of locking devices can be adopted for this purpose. A first possible locking device is shown in Figs. 4 and 5 which comprises a pair of aligned holes 15 through both fins 12 and a row of holes 16 along the edge of fin 11 that can be aligned with hole pair 15. A catch device generically indicated with number 17 is joined to one of fins 12 and includes a pivot 18 pressed by a spring which — by engaging simultaneously through holes pair 15 and one of holes 16 aligned with them — blocks any possible rotation about the articulated joint. Another embodiment of a locking device for the articulated joint on the supporting base of the ladder according to the invention is shown in Fig. 6. Transversal rod 14, which supports the whole ladder, has a central fin 20 that engages between a

pair of fins 21 projecting from transversal rod 4a of base 4. A pivot 15 pivotally connects fins 20 and 21. On fins 21 two horizontal slots 22 and 23 are formed, both in the same plane, in which pivot 24 and pivot 25 engage respectively, each supporting stops 26 and 27, respectively, located between fins pair 21 and under fin 20. The two stops 26 and 27 can therefore slide independently between fins 21 so as to be brought to halt at the edge of fin 20 from opposite sides with respect to pivot 15, thus preventing any rotational movement of fin 20 and therefore of the whole ladder, thereby blocking it at a chosen angle .

In order to fix the ladder to transversal rod 14 several different solutions are available. The stanchion ends of many ladders have a transversal notch that is used to connect extensions to the ladder. Transversal rod 14 could be shaped so as to be suited to fit into said notch and then be attached to it with some means of connection, for example, nuts and bolts. Another possible solution is shown in Fig. 7 and consists in attaching to transversal rod 14 a pair of sliding pocket supports 30 into which stanchion ends 3 can fit. Support 30 has a transversal seat 31 into which the end of transversal rod 14 fits and a longitudinal seat or pocket 32 into which stanchion end 3 fits and to which it is attached by means of a U-shaped bolt 33 that wraps around the stanchion and inserts into holes (not shown) formed in the wall of the pocket 32 itself. The latter can be dimensioned so as to be suited to contain stanchion ends of the different shapes and dimensions most commonly used. Moreover, by forming the transversal seat 31 larger than the

height of the transversal rod 14 it is possible to utilize pocket supports 30 also for ladders with converging stanchions .

Ladders built according to the invention that do not include central stanchion 1 can nevertheless be provided on the top with a tip 40, as shown in Fig. 8. Tip 40 is made of a rod 41 with a shaped end 42, for example, as a fork, as described above, said rod being inserted inside two brackets 43 attached to the two uppermost rungs 44 of the ladder. Rod 41 can be free to slide inside brackets 43 to allow a wider selection of positions for shaped end 42. The sliding and stopping of rod 41 into the chosen position can be controlled with known devices and therefore is not described here.

According to the present invention it is therefore possible to build a portable ladder with an articulated supporting base such as in the above- illustrated embodiments or to transform traditional portable ladders into articulated ladders by providing the articulated supporting base prepared for attaching on it the stanchion ends of the ladder .

Moreover, it is evident that many different embodiments can be designed for the articulated joint on the supporting base, for the locking device of said joint, when present, and for the means of connecting the stanchion ends of the ladder to the supporting base, all of which are covered by the present invention. In particular, the supporting tip provided for at the central stanchion end 1 or to be attached to the last two rungs of the ladder could have a shape different from the one here illustrated, or the fork opening could be variable.

These and other variations and/or modifications can be brought to the portable ladder according to the present invention, without departing from the scope of the invention itself as defined in the appended claims .