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Knuckle Booms vs. Straight Booms. What are the Differences?

If you’re planning a construction job that requires you to work high above the ground, you may have considered using an aerial platform. With several to choose from, including scissor lifts and cherry pickers, it can be difficult to know what will work best for you. However, if you need to get up really high and don’t have a lot of room to work with, then you may want to consider a boom lift.

Most types of boom lifts generally offer smaller aerial work platforms than scissor lifts, and are often only large enough for a single worker. They can be found in various sizes, ranging from 10 metres all the way up to 60 metres and can be either electric or diesel powered. One of the biggest distinctions among these versatile machines, is the two designs that are available: knuckle booms and straight boom lifts.

Let’s take a closer look at what sets these two types of boom lift apart, and which type of lift might be the best choice for your job.

What is a knuckle boom lift?

Knuckle boom lifts are aerial machines used to access difficult-to-reach locations. Most models come with a 360-degree base turntable, so they can swivel in any direction. However, the most notable feature that sets them apart is their joint arm and segmented boom sections. In fact, they come with multiple joints (typically two or three) like a finger, which explains why they’re called “knuckle booms.”

These lifts offer a level of dexterity and versatility that other lifts can’t provide, with an impressive reach/working height of up to 45 metres up, over, and around. The knuckles on the articulating arm, or jib, can bend around corners, past obstacles, and over walls to give a worker access to areas that would otherwise be impossible to reach.

Knuckle booms can also be used indoors because their arms can bend and contract to squeeze into tight spaces. Models with quiet engines are available with no emissions that run on electric power for use indoors.

Best for:

  • Hard-to-reach areas on your worksite

  • Jobs that require you to adjust your lift position frequently

  • Working in a smaller or tighter space

  • Up-and-over work spaces

What is a straight boom lift?

Straight boom lifts offer an extended outreach, similar to the knuckle boom, and in some cases can stretch even farther—up to 56 metres. However, they lack the joints present on an articulating arm, so they’re less versatile in tight areas. They can extend straight up or straight out at an angle, but they can’t bend, instead they expand and contract like a telescope.

Rugged tyres can allow them to operate well on rough terrain, and because they run on diesel fuel, they tend to be used outdoors.

Best for:

  • Reaching far during specific tasks (up to 56 metres)

  • Working on rough terrain

  • Lifting materials to high positions using elevated work platforms

How to Choose the Right Boom Lift

When deciding between these two kinds of aerial lifts, you’ll want to know the nature of the job and the layout of your work areas. How high or far out do you need to go? How many obstacles (walls, trees, power lines) will you be dealing with? Will you be operating indoors or outdoors? Will you be working over rugged terrain?

Agility vs. Versatility

The most recognisable difference between these two types of lift equipment is the knuckle boom’s shape. They have multiple pivot points (allowing up-and-over access), thus allowing you to reach tight spaces or hard-to-reach spots. Straight booms, by contrast, extend out in a straight line.

  • Knuckle boom lifts are ideal for reaching over or around places such as ceiling joists, roofs, warehouse shelves, etc.

  • Straight boom lifts have more versatility to perform tasks that may be higher or farther out. They’re great for working at distances on worksites where operating closely isn’t an option. Straight booms are beneficial for tasks such as, building bridges and working high up on skyscrapers.

Vertical and Horizontal Reach

Another difference is their maximum reach capacity. Straight boom lifts typically have a higher vertical reach and horizontal reach than knuckle booms. However, straight booms need a bigger workspace and plenty of room to achieve their extended reach.

  • Knuckle boom lifts have less reach than telescopic booms, but are ideal for moving around certain obstacles or places.

  • Straight boom lifts have a greater vertical reach and horizontal reach- up to 56 metres and are commonly used for high-rise buildings.

Indoor vs. Outdoor Use

Are you working in an indoor warehouse or on rough outdoor terrain? In that case, straight boom lifts would be the best choice for outdoor job sites with a lot of room and space to reach.

  • Knuckle boom lifts are ideal for indoor work since they can access narrow areas or walkways. They can be used for scanning in warehouses, which are often cluttered with stacks of inventory, and they can be used for maintenance work such as plumbing and ceiling repair.

  • Straight boom lifts are commonly used in outdoor construction sites such as electrical work, painting, bridgework, or other tasks that require high or distant access.

Type of Engine

Your required power source is an important factor to consider when choosing a boom lift. Indoor operations will likely call for an electric lift, while outdoor jobs may require more power from a diesel engine.

Diesel-Powered Engines

Diesel engines are generally used outdoors because of the fumes they emit. Both straight and knuckle diesel lifts are available in larger models with a greater range of reach: straight boom lifts from 12 metres to 56 metres and knuckle boom lifts from 10 metres to 45 metres. Diesel engines emit fumes, but can also provide more power for dealing with rough terrain.

Electric-Powered Engines

Smaller knuckle boom lifts, suitable for indoor use, are available for hire in 10- to 18-metre models. These battery-powered engines don’t emit fumes and are much quieter.

Need to Hire a Boom Lift?

If you're looking to hire a boom lift, Australian Access Hire offers a range of knuckle and straight boom lifts on a short-term or long term basis. Because these pieces of equipment are expensive to purchase, hiring is your best option for most jobs.

For more information, or to make an enquiry, give us a call on 133 224.

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