Description

MACHINE MOUNTED LADDER HAVING INDIVIDUALLY REMOVABLE

STEPS

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 solves one or more of the problems set forth above.

Summary of the Disclosure

In one exemplary aspect, the present disclosure is directed to a ladder for a mobile vehicle. The ladder may include a first side rail fixedly connected to the mobile vehicle, and a second rail fixedly connected to the mobile vehicle. The ladder may also include a plurality of steps removably connected to the first and second side rails in a face-mount configuration.

In another aspect, the present disclosure is directed to a method of servicing a ladder. The method may include fixedly securing a first side rail and a second side rail to a mobile vehicle. The method may also include butting a first planar surface and a second planar surface of a step against a first planar surface of the first side rail and a second planar surface of the second side rail while the first and second side rails are fixedly secured to the mobile vehicle. The method may additionally include 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.

Brief Description of the Drawings

Fig. l is a pictorial representation of an exemplary disclosed vehicle; and

Fig. 2 is a pictorial representation of an exemplary disclosed ladder for use with the vehicle of Fig. 1.

Detailed Description

An exemplary embodiment of a vehicle 100 is illustrated in FIG. 1. In this embodiment, vehicle 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 vehicle 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 vehicle 100.

Operator's cab 108 may be supported on frame 106. The operator's station could also be open and may comprise any location from which an operator can operate vehicle 100. The operator's station may include controls for operating and driving vehicle 100. Vehicle 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 1 16 may include a first side rail 118, a second side rail 120, a plurality of steps 134, and an extension step assembly 146. Side rails 118 and 120 may provide fixed support for mounting steps 134 to vehicle 100, allowing

an operator to safely enter and exit operator's cab 108 of vehicle 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 metals 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. 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 1 18 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.

Side rails 118 and 120 may include a plurality of weld nuts 128 mounted to step-receiving flange 124. Step-receiving flange 124 may include a hole 130. Weld nut 128 may be mounted to step-receiving flange 124 so that weld nut 128 is aligned with hole 130. In this arrangement, a fastener 142 may be passed through step 134 into connected engagement with side rails 118 and 120. 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 1 16 to gain entry to operator's cab 108. Each step 134 may comprise a step body 136 and a tread plate portion 138. 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 metal known in the art.

The ends 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. 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 and weld nuts 128 of side rails 118 and 120. Fastener 142 may be inserted through each aligned hole 130, weld nut 128, and bore 140. 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. Extension step assembly 146 may provide a secure foothold, close to the ground, for an operator to step on while entering and exiting operator's cab 108 of vehicle 100. Extension step assembly 146 may include a first side portion 148, a second side portion 150, and a step 134. Side portions 148 and 150 may be elongated flexible members made from any suitable flexible material known in the art, such as elastomer or rubber.

A top end of each side portion 148 and 150 may include holes 156. A bottom end of step-receiving flanges 124 may also include holes 156. Weld nuts 128 may be mounted to step-receiving flanges 124 in alignment with holes 156. The top ends of side portions 148 and 150 may be aligned with the

bottom ends of step-receiving flanges 124 so that holes 156 of side portions 148 and 150 are aligned with holes 156 of step-receiving flanges 124. One or more fasteners 160 may be placed through holes 156 of side portions 148 and 150 to engage the weld nuts of step-receiving flanges 124. Fasteners 160 may be of a type similar to fasteners 142, and may also include washer plates 122.

One or more steps 134, substantially identical to the other steps 134 of access system 116, may be removably mounted between inside faces of side portions 148 and 150. Side portions 148 and 150 may contain holes 162. Holes 162 may be aligned with bores 140 of step 134. Multiple bores 140 may be used. There may be, for example, two bores 140 on the side of step 134 facing side portion 148, side portion 148 having two holes 162 aligned with bores 140. The side of step 134 facing side portion 150 may also have two bores 140, aligned with two holes 162 of side portion 150. A fastener 164 may be removably inserted through each hole 162 and bore 140. Fasteners 164 may be of a type similar to fasteners 142, and may also include washer plates 122.

Industrial Applicability

The disclosed access system may provide an easily maintained means for accessing an operator's cab of a vehicle. 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 vehicle 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 1 18 and 120 may extend past the bottom of frame 106, and the upper portions of side rails 118 and 120 may extend to platform 114.

The operator may mount a plurality of steps 134 between side rails 118 and 120. The operator may mount extension step assembly 146 to the lower portions of 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. The operator may also replace damaged step 134, located in extension step assembly 146 between side portions 148 and 150, in a similar manner.

Access system 116 may be used on a wide range of vehicles, 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 vehicle 100 that reduces the scope and costs of maintenance. Steps 134 and extension step assembly 146 of access system 116 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 vehicles.

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. For example,

an alternative embodiment may include weld nuts that are mounted to the steps instead of the side rails. Bolts may then be passed through the side rails to engage the steps. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.