Aerial lifts for high-level maintenance

October 1st, 2001

Aerial lifts for high-level maintenance

Published in: Plant Engineering

Date: 10/1/2001
By: Foszcz, Joseph L.

Aerial work platforms provide a safe and efficient means of getting to hard-to-reach overhead areas. They can quickly carry an operator, with tools and materials, to places that would require setting up ladders or scaffolding.

An advantage of the aerial work platform is its ability to maneuver in tight spaces and hard-to-reach areas. Most of these units are self-propelled. There are models for use on smooth, hard, level surfaces such as concrete, asphalt, or tile and others for use on rough terrain.

Where overhead work is required, plants use these devices in maintenance and repair functions. Since there are many designs for aerial work platforms, several types can be used in the same application. The selection depends on each plant’s individual requirements.

Some small units are not self-propelled yet are easy to use on hard, flat surfaces. They require some means of pushing or towing. Larger models have their own power sources such as gasoline, diesel, LP gas engines, or batteries. Closed environments may dictate the use of batteries or LP gas.

In some cases aerial work platforms can be equipped with dual power sources, such as an internal combustion engine for outdoor work and an LP gas, dual-fuel engine for indoor work or for locations where recharging is inconvenient.

Aerial work platform functions can be handled with hydraulic or electric controls that are designed for easy and safe operation. Dual controls are usually provided, one at ground level and one on the work platform. If there are control or operator problems, ground level controls can be used to maneuver and lower the platform.

Safety

Units are equipped with safety features and are manufactured to meet all applicable ANSI and OSHA safety requirements. They also conform to approved

requirements for materials, welding, electrical, wiring, workmanship, and load ratings.

Safety features include protection to prevent controls from being accidentally activated, emergency power systems, regulators that govern operating speeds, and locking cylinders, if there is a loss of hydraulic power.

Self-propelled and narrow-slab scissors lifts have pothole protection. This is a bar that lowers to within 1/2-in. of the slab to prevent excessive tipping should a wheel drop onto a pothole.

Some units are equipped with braking systems that set automatically when the machine comes to a stop or when power fails. Tilt sensors prevent operation when units are tipped 3 deg side-to-side or 6 deg front to back. Warning buzzers and lights activate when there is any platform movement.

Most units are equipped with 42-in, high safety rails and 4 in. or 6 in. kick plates. The kick plate feature prevents materials or tools from falling from the floor of the platform and keeps the operator’s feet within the confines of the platform for firm footing.

Scissors lifts

More than 60% of aerial work platforms made today are scissors lifts. The inherent limitation of vertical travel is overcome by platforms that can extend in any direction and be customized for a particular application (Fig. 1).

The largest platforms and highest load capacities in manned aerial workstations are found in scissors lifts. Platform sizes up to 6 ft 11 in. x 25 ft and capacities to 2500 lb are available. Platforms can be extended up to 84 in. Working heights can reach 108 ft.

Platform designs range from simple rectangular shapes to extensible ends reaching hard-to-get-at places and custom-designed shapes for specialized work. Platforms have nonskid working surfaces, guard rails, and toe plates. Electrical outlets for power tools can be provided.

Scissors lifts retract to form a compact package that is readily moveable throughout the plant. Typical units will fit through a standard 36 x 80-in. doorway while some models are only 32-in, wide.

Mast/vertical

Mast/vertical lift type work platforms are one of the most common means of overhead access for maintenance and light repair work. Units are available in push-around and self-propelled models. They are lightweight, portable, and low-cost.

Telescoping mast work platforms are usually small, one-man units, for light-duty work. Typical load capacities are 300 lb for reach heights of 41ft (Fig. 2). Heavy-duty units have 52 x 204-in, platforms that will elevate 2000 lb loads to a height of 87-ft.

Mast-type work platforms are available in configurations to solve most plant problems. Designs include one-man baskets, rotating masts, platforms with extensions, and platforms on arms for over-and-under work.

Compact mast units fit through standard doorways. Special designs can fit through 24-in, wide openings. Narrow baskets, 22 in. wide, pass through ceiling panels and other overhead openings.

Articulated arm

An outgrowth of the vertical mast one-man lift is the articulated arm lift. The simple design allows horizontal extensions to 79-ft and vertical working heights to 150-ft. This type of work platform can place a man and material weighing up to 500 lb in extremely out-of-the way work situations.

Manned buckets and upper booms are available in fiberglass to provide electrical insulation. Hydraulic power tool outlets can be supplied with insulated buckets. Noninsulated buckets can be equipped with electric power tool outlets.

These units can also be readily adapted to serve as material lifts. Hooks, hoists, or other attachments to handle up to a 2250-lb load can replace manned buckets.

Articulated arm units are available as self-propelled or trailer-mounted, since many applications require travel between job sites. For trailer-mounted units, long side reaches require the use of outriggers, which can be extended manually or under power. Self-propelled units have self-contained counterweights and do not require outriggers.

Telescoping boom

Telescoping boom aerial work platforms can operate in confined spaces to reach 120 ft vertically and 62 ft horizontally. Load capacities range from 300 to 1100 lb.

Platform sizes range from 24 x 24 in. to 36 x 96 in. Platforms can be swiveled 18-deg at the end of the boom to provide access to most jobs. Extending the telescoping boom while it is below a horizontal plane allows the platform to reach work below ground level. An articulating arm provides additional mobility.

Platforms can be supplied with pneumatic, hydraulic, or electric power sources for a variety of tools. The supply lines can be placed inside the telescoping boom sections to protect them from damage. Telescoping booms can be self propelled (Fig. 3), or truck mounted.

Telescoping/articulating I booms

An interesting variation to telescoping booms is the addition of an articulating arm that provides the ability to reach up, out, and over obstructions. This configuration, sometimes called a jib or knuckle boom, can extend up to 63-ft horizontally and 126ft vertically while carrying loads up to 590-lb.

Some platforms have automatic leveling and 180-deg rotation. Pneumatic, hydraulic, and electric power can be supplied to platforms for power tools. Platform sizes are available from 30 x 48 in. to 36 x 96 in. Controls have a foot-actuated dead man switch to stop. all movement when released.

Booms use self-lubricating wear pads that require no lubrication and do not attract dirt and grit. Controls and power lines are enclosed or protected by the boom.

The compact dimensions of the turret and location of the ballast within it ensure the turret does not overhang at any point in the turret’s 360-deg rotation. This absence of overhang is known as zero tailswing and allows the boom to rotate in a space only as wide as the tire width (Fig. 4).

Zero tailswing and articulated arm placement allow most units to maneuver in narrow aisles and congested areas where space is limited. A battery or engine usually supplies power for self propelled units.

Plant Engineering extends it appreciation to JLG Industries, Inc., for its assistance in the preparation of this article and in providing the cover photo.

Aerial work platform manufacturers

The following companies provided input for this article by responding to

a written request from Plant Engineering magazine.

Bil-Jax, Inc.

Bushman Equipment

Cotterman Co.

Genie Industries

Grove Worldwide

JLG Industries, Inc.

Lift-A-Loft Corp.

LPI Lift Systems

Skyjack

Other aerial lift manufacturers include: Air Technical Industries,

airtechnical.com; Ballymore Co., Inc., ballymore.com; Carbis, Inc.,

carbis.net; EGA Products, Inc., egaproducts.com; Handling Specialty,

Inc., handling.com

Aerial lifts for high-level maintenance

Aerial lifts for high-level maintenance

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