Patent Application
20200199937
The present disclosure generally relates to ladders, and more particularly relates to ladders used for access to trucks and other work machines.
Many work machines require the use of a ladder to gain access to the operator cabin, cargo bed, or other areas of the machines. For example, with an off-highway truck (OHT), the operator cabin may be several feet above ground, and ladders or stairs may be fixed to the side of the OHT to allow access. The same may be true with mining trucks and other work machines, including but not limited to large excavators, graders, bulldozers, and the like.
To gain access to the fixed exterior ladder or stairs of such OHTs or other machines, a break-away ladder is typically provided. The break-away ladder may only be a rung or two and be provided at a height enabling a human operator to step directly thereon from the ground. However, as such steps have relatively little ground clearance, they are typically designed so as to move, fold or break away from the truck if it were to engage the ground, thereby avoiding significant damage.
In addition, such break-away ladders are often movable from a stowed position to an operational position. However, current ladders often do not reliably lock into position and can thus swing back and forth. Moreover, current break away ladders often include multiple welds lending themselves to fatigue and failure over time, and do not allow for adequate debris fall-through. In other words, given the work environment of such OHTs, it is desirable for dirt and other worksite debris not to build up on the steps of the OHT ladder. In fact, current ISO standards have requirements in this regard.
One example of a prior art ladder is disclosed in U.S. Pat. No. 7,025,174. The '174 patent discloses a truck ladder deployable from a folded position under a trailer bed of the truck to an outward operational position. However, such a ladder suffers from many of the drawbacks mentioned above and thus improvement is desired.
In accordance with an exemplary embodiment of the present disclosure, a rung which can be installed in a ladder is disclosed which comprises a first plate having first and second ends, each of the first and second ends having a relief tab and an opening, and a second plate, the second plate being identical to the first plate, the first and second plates being nestable such that the relief tabs of the first plate insert through the openings of the second plate to form the rungs.
In accordance with another aspect of the disclosure, a ladder for use on a work machine is disclosed wherein the ladder comprises first and second rails adapted to movably attach to the work machine; and a plurality of rungs extending between the first and second rails, each rung including first and second plates, each plate including first and second ends, each end having a relief tab and an opening, the first and second plates being nestable such that the relief tabs of the first plate insert through the openings of the second plate.
In accordance with yet another aspect of the disclosure, a method of manufacturing a break away ladder for a work machine is disclosed wherein the method comprises providing a first plate having first and second ends and first and second sides, providing a second plate having first and second ends and first and second sides, machining a c-shaped cut in each of the first and second ends, bending each of the first and second ends such that each of the first and second ends includes a relief tab and an opening, nesting the first plate into the second plate such that the relief tabs of the first plate are inserted through the openings of the second plate to form a rung.
These and other aspects and features of the present disclosure will be more readily understood upon reading the following detailed description when taken in conjunction with the accompanying drawings.
While the following detailed description will made with reference to certain illustrative embodiments, it is to be understood that such embodiments are only exemplary and that other embodiments exist are included within the scope of the equivalents of the present application and appended claims.
Referring now to the drawings, and with specific reference to
As shown in
While two ladders 12 are shown, it is to be understood that a greater or lesser number of ladders can be provided. However, regardless of the number of ladders employed, each is provided in “break-away” fashion, meaning they are movable between a stowed position to a deployed position. For example, as the ladders 12 have relatively little ground clearance, each ladder 12 may be hingedly attached to the bumper 16 such that upon impact with the ground 22, in either a forward or rearward direction, the ladder 12 can fold upwardly and avoid more significant damage. In addition, as will described in further detail herein, the ladder 12 of the present disclosure is “mass-tuned” so as to facilitate keeping the ladder 12 in one of the stowed and deployed positions until movement is desired and initiated by the operator.
In the paragraphs that follow, the construction of the ladders 12 will be described. In so doing, a ladder which includes no welds, which cannot be mis-assembled, which provides enhanced debris fall-through, which meets ISO standards (see, for example ISO Standard 2867), and which has sufficient mass to lock the ladder in position is provided.
Referring to
With specific reference to
The resulting structure depicted in
Such construction also affords benefits with respect to debris fall through. More specifically, the plate bodies 43 of each plate 32 are spaced apart from each other a distance 52 providing ample room for debris, e.g., mud from operator shoes or impact with the ground, etc., to fall therethrough. This so-called debris fall-through area 54 is actually regulated by ISO standards to be 40 mm or less in width for safety purposes, and the current design so complies.
Turning now to
As mentioned above, given the ground clearance of the work machine 10, only a rung or two may be necessary to provide sufficient length to enable an operator to step thereon from the ground 22. The resulting assembled ladder 12 is depicted in
Still referring to
In operation, the teachings of the present disclosure may find applicability in many industries. For example, the rung 34 and ladder 12 disclosed herein could be used in the construction of work machines 10, including but not limited to, off-highway trucks, mining trucks and large excavators. Moreover, they could be used on agricultural equipment such as tractors and combines, commercial vehicles such as on-highway semis and tractor-trailers, delivery trucks and the like, marine ladders, military equipment, aerospace ladders, etc. In each application, the rung and ladders disclosed herein provide robust construction, no welds, reliable assembly, maximized debris fall through, and mass tuning so as to lock the ladder into a given position.
Referring now to
In a step 116, each end 36, 38 is then bent to form the relief tab 44 and opening 46. More specifically, the protruding tab 113 is curled away from the plate body 43, such as about a fixed journal or the like. Given the presence of the c-shaped cut 114, this causes the relief tab 44 to pivot away from the plate body 43. Each end 36, 38 thus has a t-shaped confirmation, with the resulting rung half 72 being depicted in
Once both rung halves 72 are so formed, the first plate 32 is nested within the second plate 32 such that the relief tabs 44 of the first plate 32 are inserted into the openings 46 of the second plate 32 as shown in step 118. The resulting rung 34 is shown in
Given the identical nature of the rung halves 72, their symmetry allows for only one way of assembly, thereby avoiding improper construction. Once each rung 34 is so assembled, the rungs 34 are bolted between rails 56 as shown in step 120. More specifically, bolts 58 are extended through plates 63, rails 56, and ultimately through bolt holes 50 of each relief tab 44. Nuts 60 are then threadably attached to bolts 50 with washers 62 therebetween. As mentioned above, other fasteners and methods of fastening the rungs 34 to the rails 56 are certainly possible. The resulting ladder 12 is depicted in
Finally, the assembled ladder 12 is mounted to the off-highway truck 12 other work machine 10 as shown by step 122 in
From the foregoing, it can be seen that the present disclosure sets forth a rung and ladder which are sized and mass tuned so as to be lockable into stowed and use positions. Moreover, it provides for a more robust design with no welds to thus mitigate fatigue and failure. It also facilitates reliable assembly through the use of identical parts which can only be assembled one way, as well as improved debris fall through which complies with current ISO standards.
