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Why Is It Called a Knuckle Boom?

A knuckle boom is called a knuckle boom because of the articulating joints on the boom of the lift or crane. These joints look like knuckles on fingers that bend rather than move in and out like the arm of a telescopic boom. 

What is a Knuckle Boom?

A knuckle boom, also known as an articulating boom, has a lift arm with multiple sections separated by joints, or knuckles. The arm can move the work platform over and around obstacles due to these joints that can fold the arm out and in. 

Boom lifts have a hydraulic arm stemming from a grounded base and can have a variety of accessories connected to the end of the lift arm. Boom lifts are known for being able to reach both vertically and horizontally. 

The majority of knuckle boom lifts have a platform capacity of up to 500 pounds. However, some people can lift up to 750 pounds. Standard knuckle booms can extend from 20 to 70 feet in height. Depending on the brand and model, each knuckle boom is unique. To guarantee the greatest level of stability and safety, be careful to adhere to the manufacturer’s restrictions.

Are Knuckle Booms Lifts or Cranes?

There are both knuckle boom lifts and knuckle boom cranes. A lift and a crane both serve very different purposes. A boom lift does not have the same lifting strength as a crane, and a crane is not suitable for lifting workers. 

This means that articulating boom lifts and articulating boom cranes (knuckle boom cranes) cannot be interchangeable. The only exception are accessories approved by the knuckle boom’s manufacturer. Knuckle boom lifts, however, are not rated to lift as much as a knuckle boom crane even with certain crane type accessories. 

Lift Type Knuckle Booms

Knuckle boom lifts have a bucket or work platform at the end of the lift arm that is used for raising employees up to work areas in high or hard-to-reach places. Knuckle boom lifts fall under the category of aerial lifts, or Mobile Elevated Work Platforms (MEWPs). They are especially versatile for working in tight areas and their small base allows them to easily be used for indoor work as well. 

Are Telescopic Boom Lifts and Knuckle Boom Lifts the Same?

Knuckle boom lifts are interchangeable with the term articulating boom lifts. This means that the arm can bend and move both vertically and horizontally. A telescopic boom lift, also known as a straight boom lift, has an arm that can only move straight outward and inward like a handheld telescope does. These two different styles of booms are not the same and in fact, are completely different. 

Crane Type Knuckle Booms

Knuckle boom cranes, also called knuckle boom trucks, have some kind of hook or hoist line and winch on the end of the lift arm. The base of knuckle boom cranes is usually a truck or fixed base that is larger and heavier than the small mobile base of most knuckle boom lifts. This means they are also most commonly used for outdoor work and not for indoor work. 

Compared to other cranes, knuckle boom cranes are rather versatile cranes that are especially effective on sites where there are overhead obstructions. They have far fewer travel limitations compared to loader and mobile cranes, making them ideal for outdoor work. However, they are not as powerful and can only move medium sized objects such as construction materials, HVAC units, and generators. 

Are Picker Cranes and Knuckle Boom Cranes the Same?

Picker cranes are usually much smaller than knuckle boom cranes, but this depends on the make and the model. They are not the same, although some models of picker cranes look and function similarly to a knuckle boom crane and some come mounted on a truck. Picker cranes also have telescopic boom models, which are completely different from knuckle boom cranes, which have an articulating boom. 

What Kind of Work are Knuckle Booms Used For?

Knuckle boom lifts are commonly used by businesses in the oil, forestry, and construction industries. Common uses of this boom lift include electrical and piping repairs, exterior cleaning jobs, and maintenance projects.

A knuckle boom lift is often used for working in tight or elevated spaces. The lift gives workers the ability to lift themselves and their tools and work materials up and over with unprecedented precision. Once in the air, a knuckle boom crane can extend and bend to the left and right and not just up and down. 

Knuckle boom trucks are commonly used for lifting heavy small to medium sized objects. This could include construction materials, tree removal, and installing AC units. They are great for using at smaller workplaces outdoors. 

Knuckle Boom OSHA Requirements

When it comes to the manufacturing, maintaining, and operating knuckle boom lifts, the Occupational Safety and Health Administration (OSHA) directly mentions the standards established by the American National Standards Institute (ANSI). It is important to note that all lifts are considered aerial lifts by OSHA with the exception of scissor lifts, which OSHA considers to be scaffolding.

OSHA does have stringent requirements when it comes to knuckle boom lift training. Here are the topics that must be covered in a knuckle boom lift training:

It is also required that anyone operating or working on or around the knuckle boom lift must have successfully completed an OSHA Aligned safety training course before their initial assignment. 

Knuckle Boom ANSI Standards

While OSHA tends to use the term aerial lifts when referring to lifts of any kind, ANSI prefers to use the term Mobile Elevated Work Platforms (MEWPs). 

ANSI standards state that a Safe Use Plan must be established for each specific MEWP. This plan should include a worksite assessment to identify hazards, evaluate risk, create control measures, and communicate results with the employees. The requirements of a safe use plan also can include:

Boom Lift Training

One of the most important things to ensure your safety and the safety of those around you is to be trained. Understanding the heavy machinery you are operating and procedures for safe work operations will be the difference that prevents workplace injury and death. 

Here at Hard Hat Training, we offer knuckle boom training for both types of knuckle booms. We have Knuckle Boom Truck Training for knuckle boom crane operators, and Aerial Lift/MEWP training for knuckle boom lift operators.

Our training comes in four formats: online, onsite, training kit, and competent person. Depending on what works best for you and your company, any of these formats will give you the certification you need for working with knuckle booms.