In recent years the popularity and the varied manner of utilization of recreational vehicles has increased considerably. Recreational vehicles frequently take the form of motor vehicles which include a compartment located behind the vehicle cab of sufficient height to accommodate the entry and occupancy thereof by individuals utilizing the recreational vehicle. Such recreational vehicles often take the form of temporary mobile homes, campers, vans, camper compartments mounted on pick up trucks, and vehicles employing other types of large compartments the roofs of which are inaccessible to a person without some form of aid in ascending. To allow people to climb and reach the roofs of such vehicles in order to position baggage, repair equipment, to check the fastenings of cargo stored overhead, to make observations and so forth, recreational vehicles have in the past been supplied with upright ladders having vertically space steps or rungs.
The conventional form which such auxiliary ladders take involves a construction in which upright rails or stringers are provided and upon which unitary steps are mounted. The utilization of such single piece steps involves considerable disadvantages. To assemble conventional ladders in which the steps are formed of a single structure, holes are first formed in the steps at the proper distance of rail spacing. The steps must then be strung on to the rails. That is, the steps one by one are inserted onto the ends of the rails with the rails passing through the holes in the steps provided for this purpose. The steps are then worked along the rails away from the ends thereof toward their appropriate positions. The steps are then secured in place by conventional means, such as screws or bolts or welding.
The assembly of conventional ladders can only be performed with considerable effort. It is frequently very difficult to work the unitary ladder steps longitudinally along the rails, since, if the steps are properly formed, there is a close fit between the rails and the apertures in the steps to accommodate the rails. It is therefore quite important in manipulating the steps along the rails to at all times maintain the steps percisely normal with respect to both rails. This is extremely difficult, as progress in working the steps along the rails tends to be uneven, thereby causing the steps to become cocked or tilted relative to their proper orientation on the rails. Working the steps into their proper positions thereby becomes an arduous and time consuming job at best.
The conventional manner of ladder construction involves other disadvantageous features. In working the individual steps onto the rails, the steps, when temporarily misaligned tend to score and scratch the rails. The paint finish of painted rails almost invariably becomes severely scratched and the rails themselves frequently become scored with unslightly indentations which result from the unintentional twisting of the steps relative to the rails during assembly. Furthermore, even slight imperfections in the cross section of the rails make assembly of steps thereon exceedingly difficult. For example, if a rail has been struck or bent slightly prior to stringing the steps, the steps frequently can not even be assembled on to the rails at all, since the apertures will not allow the steps to be moved past such imperfections in the rail cross section.
A further disadvantage of conventional recreational vehicle ladder construction is that because the unitary steps must be moved along the lengths of the rails to their proper positions, rails of any cross section other than of a uniform cross section throughout are precluded. In some instances, it would be quite advantageous for rails to be formed of a nonuniform cross section. Englargements along the rails might be provided for additional support for the ladder steps or as means for attachment to the vehicle. For example, the ends of the rails, rather than assuming the conventional circular cross section throughout, might terminate in flattened tabs which could be bolted onto the vehicle or onto mounting brackets.
It is an object of the present invention to provide an improved form of ladder construction to obviate the foregoing difficulties. The present invention does not employ unitary steps which must be mounted on the ladder from the ends of the rails. Rather, the present invention employs bifurcated steps divided generally along a plane passing through the two rails.
It should be understood that in the use of bifurcated steps according to the present invention the exact division between the two sections of the steps need not conform to any particular geometry. That is, the division between the sections can be irregular as long as the sections can be fitted into contact with the upright rails of the ladder from opposite sides thereof to cooperate to entrap the rails therebetween. It is necessary only that the sections of the steps are freely moveable transversely toward the rails to assume a position in snug contact therewith. Thus, when rails of circular cross section are employed it is necessary that the recesses formed in the step sections to receive the rails not exceed 180.degree.. Also, if the rails are equipped with any laterally extending flanges or projections, the division between the steps sections must be such that the two sections together can be moved to encompass such projections. These constraints are directed to the end that none of the step sections need be installed from the ends of the rails.
A further object of the invention is the provision of divided ladder steps which once mounted, will remain in position on the rails. For this reason, each of the two sections or segments of a step is provided with arms that extend toward the opposite section or segment. The arms of one step section are provided with connectors, such as hooks while the opposing arms of the opposite step section are provided with means for receiving the connectors such as latches, so that when the two sections are moved together to encompass the rails, the hooks engage the latches in interlocking fashion drawing both step sections into contact with the rails and immobilizing them relative thereto. In the actual construction of the ladder the first or the outer section of each step is mounted in a jig. After that, the rails are placed over the outer sections as they are mounted in place in the jig. Then the inner sections of the steps are placed over the outer step sections and snapped into place using the latches. Thereafter, the self tapping screws secure the assembly.
A further object of the invention is to provide ladder steps which meet in contact with the upright ladder rails in at least two different planes of contact. Preferably each of the step sections includes an upper and lower transversely extending surface, the two surfaces being joined together by webs extending therebetween. The provision of steps which are mounted to contract the ladder rails along two different planes gives added stability to the steps to resist the torsional forces that act thereon during use. Steps formed according to the preferred embodiment of the invention thereby are much safer than conventional steps formed largely in a single plane, in that even after prolonged use, they are unlikely to tilt downward under the weight of an ascending or descending individual. This provides an important safety feature for the improved recreational vehicle ladder of the invention.
An additional safety feature of the invention lies in the manner in which the fasteners mount the steps to the upright rails. Preferably, transversely extending screws are employed which pass through both step sections and through a transverse aperture in the rail itself to sandwich the rail between the two step sections. In the preferred form of the invention webs in the inwardly facing step sections are provided with recessed panels that receive the screw heads of transversely extending screws which secure the steps of the rails. The screw heads are thereby unlikely to snag the clothing of individuals using the ladder and thus cause an accidental fall. Also, the location of the screw heads, reduces the liklihood of causing scratches or other injuries to persons using the ladder.