STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

(NOT APPLICABLE)

BACKGROUND

The invention relates to a mobile elevating work platform (MEWP). In one aspect, the targeted area is the design of the chassis. In another aspect, the targeted area is the design of the vertical telescopic mast. In still another aspect, the targeted area is the design of the control box/controls configuration for the MEWP.

Existing self-propelled MEWPs typically have four wheels for stability. One version includes two steering wheels at the front of the machine. This version, however, has implementation difficulties to limit the turning radius and have the center of gyration in the middle of the rear axle (torque and speed). Additionally, it is difficult to accurately control the motors during extreme steering (90°). The system is also often overly bulky.

Another version includes two rear drive wheels that can be turned in opposite directions and two free caster wheels at the front of the machine. This version, however, suffers from bad controllability and predictability of the caster wheel movement when changing direction. Problems also arise due to wheel diameters and the large offset (king pin and wheel pin), i.e., the wheels exceed the gauge when changing direction. Stability is worse than the first version (inner tilting line by the offset value), and the construction has undesirable high sensibility to ground irregularities and to obstacles (uncontrolled wheels steering changing).

There are two types of masts typically used for these applications. A square mast includes a telescopic tube extended by means of telescopic cylinder or cylinder and chains. This proven technology has high rigidity for added stability, but requires specific dimensions for elevation beyond 3 m. Another typical mast is made of extruded aluminum profiles (e.g., telescopic forklift principle). This structure also requires specific dimensions for elevation beyond 3 m. Additionally, there are workload limitations to be at an acceptable stress level in the profile, and the construction requires many and complex components (sheaving by chains or cable), and significant assembly time.

BRIEF SUMMARY

The described embodiments in one aspect combine the advantages of existing solutions together with limiting the drawbacks including:Controllability of the steering system and predictability of the pathInsensitivity to ground irregularitiesLimitation of oversized elements and optimization of the MEWP stabilityCompact system

Objectives of the described configuration include, among other things, improved stability and optimal traction.

Another object is to propose a compact mast system that enables a telescoping height beyond 5 m without reduction in performance (mast capacity).

In an exemplary embodiment, a mobile elevating work platform includes a chassis, a pair of fixed wheels secured to the chassis, a pair of caster wheels secured to the chassis, and a driving and steering wheel secured to the chassis. A control implement coupled with the driving and steering wheel is configured to adjust a steering position of the driving and steering wheel. A drive motor is operable to drive the driving and steering wheel.

The driving and steering wheel may be secured to the chassis between the pair of caster wheels.

The control implement may be coupled with the drive motor and may include a drive switch that is configured to activate the drive motor.

The mobile elevating work platform may also include a driving wheel suspension secured between the driving and steering wheel and the chassis. In one aspect, the driving wheel suspension is a spring. The chassis may include a pivot link, where the drive motor and the driving and steering wheel are pivotally secured to the chassis via the pivot link.

The driving and steering wheel may be connected to a wheel gear that is rotatable relative to the chassis. The control implement may be coupled with a steering motor that drives a steering gear engaging the wheel gear.

The chassis may include a pair of fixed rear wheel wells, a pair of caster wheel wells, a driving and steering wheel well, and mast supports.

A mast may be secured to the chassis that is displaceable between a lowered position and a raised position, and a work platform may be coupled and displaceable with the mast. In one aspect, the mast may include a plurality of telescoping mast sections, where each of the telescoping mast sections has a cross member and two profile units one each connected to opposite ends of the cross member. Each of the two profile units may include a connector portion and a receiver portion. The mast may also include a V-shape slide member disposed between the connector portions of one of the mast sections and the receiver portions of an adjacent mast section. Each of the cross members may be longer than an adjacent cross member such that each of the telescoping mast sections fits over an adjacent mast section.

The control implement may include a housing, a handle coupled with the housing and maneuverable between an initial position and an adjusted position, and a lock bar cooperable with the handle and displaceable between a lock position and an unlock position. The handle may be maneuverable between the initial position and the adjusted position when the lock bar is in the unlock position. A back plate may be coupled with the housing and cooperable with the handle and the lock bar. The lock bar may be positioned between the handle and the back plate, and the back plate may include locking tabs engaging the handle when the lock bar is in the lock position.

