Description

REMOVABLE STEP FOR A MACHINE MOUNTED LADDER

Technical Field

This disclosure is directed to a ladder and, more particularly, to a machine mounted ladder having individually removable steps.

Background

Some large machines such as wheel loaders, off-highway trucks, excavators, and other earth-moving machines include elevated cabs accessible only by a ladder. In order to withstand the harsh environment in which the machines operate, the ladder is often a single-piece welded structure, mounted to the machine in a pivotal manner. That is, the ladder is often designed to pivot to a first position accessible by an operator when the machine is stationary, and to a second protected position when the machine is in motion. Although this type of ladder is adequate for many situations, it can also be expensive and have limited applicability. Specifically, even though the ladder can be pivoted out of the way to avoid damage, when any portion of the ladder is damaged, the entire ladder must be replaced. And because the ladder is a welded structure, it cannot be easily adjusted to fit size requirements of different applications.

One system for providing a stairway for a moving vehicle is disclosed in U.S. Patent No. 4,193,477 (the '477 patent) issued to Broyles on 18 March 1980. The '477 patent discloses a ladder structure in which a plurality of extruded aluminum steps are secured to spaced, vertically disposed side rails, each side rail having seating slots for the steps. The slots are closed by end caps, and a screw extends through the end cap and rail into a screw- receiving recess in the step. The step contains two laterally disposed screw- receiving recesses. Screws extend through the cap into those laterally disposed recesses and, along with the first screw, secure the caps firmly on the end of

the step, and the step firmly in place on the side rails. The side rails are permanently disposed on the vehicle. Because the steps are secured to the rails by way of threaded fasteners, each step may be individually replaced when damaged. Although less expensive to service, the ladder structure of the '477 patent may still be difficult to service and have limited applicability. That is, because the side rails are secured to slots in the step, a damaged step can only be replaced after removing all other steps between the damaged step and an end of the ladder structure. Depending on how the ends of the structure are connected to the vehicle, this removal process may be difficult, if not impossible. Further, because the steps are fabricated from an extruded aluminum, the ladder structure may only be able to withstand light duty applications.

The ladder of the present disclosure is directed to one or more improvements in the existing technology.

Summary of the Disclosure

In one exemplary aspect, the present disclosure is directed to a step for a ladder for a mobile machine. The step includes a step body with a first side portion and a second side portion, wherein the side portions are located on opposite ends of the step body, the first side portion being configured to facemount to a first side rail attached to the machine and the second side portion being configured to facemount to a second side rail attached to the machine. The step also includes a first plurality of bores located within the first side portion, wherein the first plurality of bores is configured to be aligned with a first plurality of holes located in the first side rail, the first plurality of bores and the first plurality of holes being configured to receive a first plurality of fasteners. The step further includes a second plurality of bores located within the second side portion, wherein the second plurality of bores is configured to be aligned with a second plurality of holes located in the second side rail, the second

plurality of bores and the second plurality of holes being configured to receive a second plurality of fasteners.

In another aspect, the present disclosure is directed to a method of servicing a step for a ladder of a mobile machine. The method includes butting a first planar surface and a second planar surface of a step against a first planar surface of a first side rail and a second planar surface of a second side rail while the first and second side rails are fixedly secured to the mobile machine. The method also includes fastening the step to the first and second side rails when the first and second planar surfaces of the step are butted against the first and second planar surfaces of the first and second side rails. The method further includes unfastening and removing the step at a later time.

Brief Description of the Drawings

Fig. l is a pictorial representation of an exemplary disclosed machine; Fig. 2 is a pictorial representation of an exemplary disclosed ladder for use with the machine of Fig. 1 ; and

Fig. 3 is a pictorial representation of an exemplary disclosed step for use with the ladder of Fig. 2.

Detailed Description An exemplary embodiment of a machine 100 is illustrated in FIG.

1. In this embodiment, machine 100 may include a front end 102, a rear end 104, a frame 106, and an operator's station, such as an enclosed operator's cab 108. Frame 106 may connect front end 102 to rear end 104, and provide structural support and integrity to machine 100. Operator's cab 108 may be mounted to frame 106. As used herein, frame 106 may refer to any structural support component that is generally secured in a fixed position on machine 100. Operator's cab 108 may be supported on frame 106. The operator's cab 108 may also be open and may comprise any location from which

an operator can operate machine 100. The operator's cab 108 may include controls for operating and driving machine 100.

Machine 100 may also include a platform 114 and an access system 116. Platform 114 may be adjacent to operator's cab 108 and, in one embodiment, may be a step or floor that an operator walks on when entering operator's cab 108. Access system 116 may extend from platform 114 toward a ground surface, providing access to platform 114 and/or operator's cab 108.

FIG. 2 shows an exemplary access system 116 in greater detail. Access system 116 may include a first side rail 118, a second side rail 120, and a plurality of steps 134. Side rails 118 and 120 may provide fixed support for mounting steps 134 to machine 100, allowing an operator to enter and exit operator's cab 108 of machine 100. Side rails 118 and 120 may be any elongated structural member known in the art, such as an L- shaped bent plate or a formed beam such as an I-beam. Side rails 118 and 120 may be fabricated from structural steel or other structural materials known in the art. In one exemplary bent plate embodiment, side rails 118 and 120 may comprise a step-receiving flange 124 and a base flange 126. Receiving flanges 124 may include a plurality of holes 130. Side rails 118 and 120 may be mounted to a vertical wall of frame 106, so that base flange 126 abuts against a vertical wall of frame 106. Any suitable means known in the art may be used for mounting side rails 118 and 120 to frame 106, including metal welding and mechanical fastening. Welds known in the art for mounting structural components, such as fillet welds, may fixedly connect base flange 126 of side rails 118 and 120 to frame 106. Any suitable method known in the art may be used to make the fillet welds, including shielded metal arc welding and submerged arc welding.

Alternatively, one or more fasteners 132 may fixedly connect base flange 126 of side rails 118 and 120 to frame 106. Fastener 132 may be any type of fastener known in the art for connecting structural elements, such as common hex-shaped steel bolts.

Each step 134 may be a generally stiff member that is fixedly mounted between side rails 118 and 120. Step 134 may provide a secure foothold for an operator using access system 116 to gain entry to operator's cab 108. Each step 134 may comprise a step body 136, a tread plate portion 138, and two side portions 135 located on opposite ends of each step 134. Step body 136 and tread plate portion 138 may be fabricated as one integral member or as separate and subsequently joined members from any suitable structural material known in the art.

Side portions 135 of step 134 abutting side rails 118 and 120 may be generally planar surfaces, without projections or recesses that interlock with side rails 118 and 120. Specifically, side portions 135 may be planar surfaces abutting planar surfaces of receiving flanges 124. Since there are no interlocking edges between the ends of step 134 and side rails 118 and 120, repair is made easier because step 134 may be removed without having to remove side rails 118 and 120. Step 134 may be removably mounted between opposing inside faces of step-receiving flanges 124. Step body 136 may include a plurality of bores 140. There may be, for example, two bores 140 on an end of step body 136 facing step-receiving flange 124 of side rail 118, and two bores 140 on an end of step body 136 facing step-receiving flange 124 of side rail 120. Step 134 may be slidable between side rails 118 and 120 while side rails 118 and 120 remain connected to frame 106 so that bores 140 are aligned with holes 130 of receiving flanges 124.

A weld nut 128 may be mounted to inside wall 137 of side portion 135 so that an aperture 139 of weld nut 128 is located coaxially with bore 140, as shown in FIG. 3. Aperture 139 of weld nut 128 may be threaded to receive a fastener 142 that may also be threaded. Apertures 139 may be smaller in diameter than holes 130 of side rails 118 and 120. Since the holes of aperture 139 may be smaller, this may reduce the need to perfectly align aperture 139 with hole 130. Further, in the event of damage to the step, a larger-sized hole 130 may

reduce damage to side rails 118 and 120 and may allow continued use of damaged or bent side rails 118 and 120.

Weld nut 128 may be mounted to side portion 135 by any suitable welding method known in the art such as, for example, arc welding. Fastener 142 may be inserted through each aligned bore 140 (in step 134), weld nut 128 (mounted to step 134), and hole 130 (in side rails 118 and 120). Fastener 142 may be inserted through each aligned bore 140, weld nut 128, and hole 130. Fastener 142 may be any type of mechanical fastening device known in the art, such as a common hex-head steel bolt. A washer plate 122 may be used for seating the head of fastener 142 against step-receiving flange 124.

Step 134 may include a plurality of openings 144. Openings 144 may serve to allow debris, such as mud, to fall through step body 136. Additionally, openings 144 may serve to reduce the weight of step 134 while not significantly reducing the structural capacity of step 134. Step 134 may also include an opening 146, where opening 146 may also serve to keep step 134 clear of debris by allowing the debris to fall through step body 136. Opening 146 may also serve to reduce the weight of step 134 while not significantly reducing the structural capacity of step 134. Step 134 may also include a plurality of openings 148. Openings 148 may perform a role similar to openings 144 and 146, and may also serve to receive a structural element such as, for example, a ladder side rail. Openings 148 may thereby provide an alternative mounting method for attaching step 134 to a machine ladder.

Step 134 may include a plurality of indentions 150 located in a plurality of walls 151. Indentions 150 may reduce the weight of step 134 while not significantly reducing the structural capacity of step body 136. Step 134 may also include a plurality of seams 152. Step 134 may be initially manufactured as a flat plate. Seams 152 may result when walls 151 and 135 are bent down to a vertical orientation to form step body 136.

Industrial Applicability

The disclosed access system may provide an easily maintained means for accessing an operator's cab of a machine. A plurality of steps may be removably mounted onto the access system, the mounting of each step being independent from the other steps. This independent mounting may allow a single damaged step to be replaced without requiring the removal of any other step or any other part of the access system. The access system may be used for heavy duty applications.

A method for servicing access system 116 of machine 100 will now be described. An operator may mount side rails 118 and 120 to frame 106, using welds or mechanical fasteners. The lower portions of side rails 118 and 120 may extend past the bottom of frame 106, and the upper portions of side rails 118 and 120 may extend to platform 1 14.

The operator may mount a plurality of steps 134 between side rails 118 and 120. If one of the plurality of steps 134 is damaged, the operator may replace only the damaged step 134, leaving the remainder of steps 134 and other parts of access system 116 undisturbed. To replace a damaged step 134, the operator may remove fasteners 142 on both sides of the step 134. Once the operator removes fasteners 142, damaged step 134 may be slidably removed from access system 116. An undamaged step 134 may then be slid into place and mounted at that location using fasteners 142. Specifically, the operator may butt the planar surface of side portion 135 against the planar surface of receiving flange 124 of side rail 118 and the planar surface of side portion 135 on the opposite side of step 134 against the planar surface of receiving flange 124 of side rail 120 (where side rail 118 and side rail 120 are fixedly secured to the mobile machine). The operator may fasten step 134 to first side rail 118 and second side rail 120 with fasteners 142 when the planar surfaces of side portions 135 of step 134 are butted against the planar surfaces of receiving flanges 124 of

first side rail 118 and second side rail 120. The operator may unfasten and remove step 134 at a later time.

Access system 116 may be used on a wide range of machines, such as a motor grader, an off-highway truck, and an on-highway truck. Access system 116 provides a means for accessing operator's cab 108 of machine 100 that reduces the scope and costs of maintenance. Steps 134 may be independently repaired, precluding the need for removing the entire access system 116. An operator need only remove and replace a single damaged step 134, leaving the remaining components of access system 116 undisturbed. This greatly reduces the time and labor necessary to repair access system 116.

Access system 116 may be fabricated from numerous materials known in the art, such as steel. This range of construction materials allows access system 116 to be used for a variety of heavy duty applications. Access system 116, if made from steel, may be appropriate for heavy duty applications such as providing access to construction machines.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed access system. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed method and apparatus. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims.