Patent Description:
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 (<NUM>°). 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).

<CIT> describes a pedestrian-controlled high lift truck that has a driving unit that is provided with steerable drive wheel. <CIT> describes a mobile vehicle comprising a frame with an operation or front side and a rear side. <CIT> describes a material handling truck of the stand-up rider type having four support wheel units <CIT> describes a mobile elevating work platform according to the preamble of claim <NUM>.

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 <NUM>. Another typical mast is made of extruded aluminum profiles (e.g., telescopic forklift principle). This structure also requires specific dimensions for elevation beyond <NUM>. 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.

The described embodiments in one aspect combine the advantages of existing solutions together with limiting the drawbacks including:.

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 <NUM> 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 includes a driving wheel suspension secured between the driving and steering wheel and the chassis, wherein the driving wheel suspension is a spring. The chassis includes 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.

These and other aspects and advantages will be described in detail with reference to the accompanying drawings, in which:.

With reference to <FIG>, an exemplary configuration of a mobile elevating work platform (MEWP) <NUM> includes a rigid chassis <NUM> with four wheels including two stabilizing caster wheels <NUM> at the front and two fixed wheels <NUM> at the rear. The four wheels <NUM>, <NUM> ensure machine stability. A driving and steering wheel <NUM> is secured to the chassis <NUM>. The driving and steering wheel <NUM> is mounted on suspension (described in more detail below) to maintain the best possible traction and absorb ground irregularities. In the exemplary construction shown in <FIG>, the driving and steering wheel <NUM> is secured to the chassis <NUM> between the pair of caster wheels <NUM>.

In an alternative construction, not part of the claimed invention, the chassis <NUM> may be provided with three wheels and two caster wheels mounted on suspension. The suspension travel directly affects traction (adaptation to ground conditions) and stability of the MEWP.

As shown in <FIG>, the chassis <NUM> includes a pair of fixed wheel wells <NUM>, a pair of caster wheel wells <NUM>, and a driving and steering wheel well <NUM>. Mast supports <NUM> are also secured to the chassis <NUM>. In the exemplary embodiment shown in <FIG>, the mast supports <NUM> are fixed to the chassis <NUM> adjacent the fixed rear wheel wells <NUM>. The fixed wheels <NUM> are secured in the fixed wheel wells <NUM>, the caster wheels <NUM> are secured in the caster wheel wells <NUM>, and the driving and steering wheel <NUM> is secured in the driving and steering wheel well <NUM>.

With reference to <FIG>, the driving and steering wheel <NUM> is secured to the chassis via a motor plate <NUM>, which is pivotally mounted via a pivot link <NUM>. A drive motor <NUM> that is operable to drive the driving and steering wheel <NUM> is secured on a top side of the motor plate <NUM>. The motor <NUM> is activated by the operator to drive the driving and steering wheel <NUM>. The motor <NUM> drives the driving and steering wheel <NUM> through a suitable gear train or the like.

A driving wheel suspension <NUM> such as a spring is secured between the motor plate <NUM> and the chassis <NUM>. As noted, the suspension <NUM> assists the driving and steering wheel <NUM> to maintain traction and absorb ground irregularities. With reference to <FIG>, the downward pivot range of the motor plate <NUM> is limited by downward limit stop <NUM> in the form of a screw or the like that extends through the chassis <NUM> into the pivot path of the motor plate <NUM>. The assembly may include a similar stop on an opposite side of the motor plate <NUM>. In some embodiments, the downward range of the motor plate <NUM> may be limited to <NUM>. The upward pivot range of the motor plate <NUM> is limited by a spring holder <NUM> to which the spring <NUM> is secured. The spring holder <NUM> may be fixed to the chassis <NUM>. In an exemplary embodiment shown in <FIG>, the assembly includes two lateral springs <NUM> coupled with the spring holder <NUM> (as opposed to a single central spring as shown in <FIG>). As the motor plate <NUM> pivots upward, the motor plate <NUM> engages the spring holder <NUM> to limit upward displacement. In some embodiments, the upward range of the motor plate <NUM> may be limited to <NUM>.

The driving and steering wheel <NUM> may be connected to a wheel gear <NUM> that is rotatable relative to the chassis <NUM>. As shown, the wheel gear <NUM> is rotatable in the motor plate <NUM>. An operator controlled control implement communicates with a steering motor <NUM>, which in some embodiments may be a hydraulic motor. The steering motor drives a steering gear <NUM> directly engaging the wheel gear <NUM> in a direction according to a control position of the operator controlled control implement.

As shown in <FIG>, a drive motor <NUM> is fixed to the motor plate <NUM>. The drive motor <NUM> may be an electric motor with a directional gear. An output shaft of the drive motor <NUM> is coupled with a lower part <NUM> including a gear reducer via a gear train or the like to rotate/drive the driving and steering wheel <NUM>.

A mast <NUM> is secured between the mast supports <NUM>. With reference to <FIG> and <FIG>, the mast <NUM> is displaceable between a lowered position and a raised position by a lift mechanism such as a hydraulic cylinder or the like. A work platform <NUM> (<FIG> and <FIG>) is secured to the mast <NUM> for displacement by the mast <NUM> between a lowered position and a raised position.

The mast <NUM> is composed of a plurality of telescoping mast sections <NUM>. Each of the mast sections or mast elements <NUM> includes two cross members (including upper cross members <NUM> and lower cross members <NUM>) and two profile units <NUM>, one each connected to opposite ends of the cross members <NUM>, <NUM>. The upper cross members <NUM> may be welded to the structure for each element. The lower cross members <NUM> are defined by fixing a lowermost mast element <NUM> to the chassis <NUM>, a first bolt on structure <NUM> at the bottom of the second element, a second bolt on structure <NUM> on the top element, and welded lower cross members on any other elements. The second bolt on structure <NUM> defines a platform support. The profile units <NUM> generally extend the length of the mast supports <NUM>.

With continued reference to <FIG> and <FIG>, each of the profile units <NUM> includes a connector portion <NUM> and a receiver portion <NUM>. A V-shaped slide member <NUM> is disposed between the connector portions <NUM> of one of the mast sections <NUM> and the receiver portions <NUM> of an adjacent mast section. As shown in <FIG>, each of the upper and lower cross members <NUM>, <NUM> is longer than an adjacent cross member <NUM>, <NUM> such that each of the telescoping mast sections <NUM> fits over an adjacent mast section. The V-shaped slide members <NUM> are preferably fixed to inside facing surfaces of the receiver portions <NUM> of the profile units <NUM> (see <FIG>).

With regard to the mast, with continued reference to the drawings, a double-slide link mast serves to guarantee on one hand the resistance and on the other hand to limit deflection. The mast fabrication process (cold forming) guarantees the necessary geometrical accuracy for the double slide link (hyperstatic). In an alternative construction, the mast may be assembled using hot forming profiles (technology used in industrial forklifts) for better compactness and rigidity. The hot rolled profile is higher in weight, however, and it is desirable to limit weight increase to the extent possible. Higher mast weight can lead to unfavorable dynamic stability of the machine (neutral for static stability because of the 'central' position of the mast).

<FIG> is an isolated view of the lift cylinder assembly <NUM> coupled between the chassis <NUM> and the mast <NUM>. <FIG> is a view of the mast from an opposite side of <FIG>. In some embodiments, the lift cylinder assembly <NUM> includes a multistage cylinder with multiple cylinders <NUM> connected two by two. Each cylinder <NUM> is connected to a mast element <NUM> to lift (and lower) the mast element <NUM>. There is no need for synchronized movement, which simplifies the mast assembly and reduces maintenance requirements (e.g., fewer parts to be lubricated). The cylinders <NUM> are connected to the mast elements <NUM> at arrows A in <FIG>.

An alternative mast may be positioned on the long side of the platform and incorporates an inverted V-shaped construction with telescoping sections. The mast provides for scissor-type functionality without the scissor mechanism.

<FIG> show a modified control box/controls configuration including control handles with ergonomically positioned switches to control operation of the machine. The switches are positioned to enable an operator to use thumbs and forefingers to control drive, steer and mast lift up/down.

The control implement <NUM> is shown in <FIG>. The control implement <NUM> includes a housing <NUM> and handles <NUM>, coupled with the housing. A display <NUM> may provide an indication of steering wheel position and other machine information. A user interface <NUM> may facilitate user-configurable steering behavior and/or user-configurable machine performance. The user may also designate "auto-center" steering wheel configuration for driving in line. Other features and functions may be accessible via the display <NUM> and user interface <NUM>.

The handles <NUM> provide for operator stability and may include a palm rest for upper body strain relief. Switches <NUM> may be positioned for natural thumb movement. Additionally, the handles <NUM> may be provided with contactless operator detection to activate control operation. The contactless operator detection may use optical technology, a capacitance sensor, or the like.

It is desirable to enable the handles <NUM> to be adjusted/positioned according to an operator's size by twisting the position of the handles <NUM>. For example, with a joystick, button and palm rest forming part of the handle <NUM>, these components are linked to follow the user's wrist configuration. It has been discovered that a few degrees of adjustment is suitable to accommodate a wide range of operator sizes. <FIG> illustrate the components and procedure for adjusting an angle position of the handle <NUM>. A lock bar <NUM> is cooperable with the handle <NUM> and the housing <NUM> and is displaceable between a lock position and an unlock position. A back plate <NUM> is coupled with the housing <NUM> and is cooperable with the handle <NUM> and the lock bar <NUM>. The lock bar <NUM> is positioned between the handle <NUM> and the back plate <NUM>. As shown in <FIG>, the back plate <NUM> includes a plurality of locking tabs <NUM> that engage corresponding locking slots <NUM> on the handle <NUM> when the lock bar <NUM> is in the lock position.

To adjust the angle position of the handle <NUM>, the lock bar <NUM> is displaced from the lock position (<FIG>) to the unlock position (<FIG>). In this position, the lock bar <NUM> releases a tab member <NUM> of the handle <NUM> so that the handle <NUM> can be laterally displaced away from the housing (to the right in <FIG>). In this position, the handle <NUM> can be rotated to a desired position (for example, one of three positions defined by tab members on the back plate <NUM> as shown in <FIG>). Once the handle <NUM> is set in a proper position, the handle is laterally displaced back toward the housing (to the left in <FIG>), and the lock bar <NUM> is returned to the lock position as shown in <FIG>. The same procedure is conducted for the handle <NUM> on the opposite side of the control implement.

The MEWP of the described embodiments incorporates components that are suitable across numerous vehicle types. The chassis and drive configuration provides for a more stable vehicle, particularly over uneven terrain. The mast may be telescoped beyond <NUM> without reduction in performance. The control implement is adjustable to accommodate varying operator sizes and ergonomics.

Claim 1:
A mobile elevating work platform comprising:
a chassis (<NUM>);
a pair of fixed wheels (<NUM>) secured to the chassis;
a pair of caster wheels (<NUM>) secured to the chassis;
a driving and steering wheel (<NUM>) secured to the chassis;
a control implement (<NUM>) coupled with the driving and steering wheel, the control implement being configured to adjust a steering position of the driving and steering wheel; and
a drive motor (<NUM>) operable to drive the driving and steering wheel,
wherein the chassis comprises a pivot link (<NUM>), and wherein the drive motor and the driving and steering wheel are pivotally secured to the chassis via the pivot link, characterized in that the mobile elevating work platform further comprising a driving wheel suspension (<NUM>) secured between the driving and steering wheel (<NUM>) and the chassis (<NUM>), wherein the driving wheel suspension (<NUM>) comprises a spring.