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A Look Into The Development of JLG’s Self-Leveling Chassis Technology

Articles - Mar 23

A Look Into The Development of JLG’s Self-Leveling Chassis Technology

Milan Klimes
Senior Chief Engineer
JLG Industries

As the demand for increased jobsite efficiency continues to grow, MEWP (mobile elevating work platform) makers are forced to adopt, deploy and develop new technologies. One such technology is the development and integration of a Self-Leveling Chassis (SLC) for JLG® boom lifts. JLG’s self-leveling chassis is a unique sub-system that allows a boom lift to automatically level on grades up to 10 degrees enabling operation on uneven jobsite terrain.
Development of JLG's Self Leveling Technology at a Glance

Real-world job sites

Self-leveling technology was developed due to watching how boom lifts are being used on job sites and talking with operators about their pain points and moments of inefficiency. 

Many applications and working environments can be challenging for a traditional boom lift to work in, even if equipped with an oscillating axle. Conventional machines are typically rated to work on a firm, level surface, which is usually defined as less than a 5-degrees of slope, yet most job sites aren't flat. In addition, the new ANSI 92.20 standard in the United States requires boom functions to be cutout when the machine is placed on slopes greater than what they are rated for.

This scenario is the root cause of many customer pain points on the jobsite since the world is neither flat nor does it come with improved surfaces. Manual labor and time are often required to set up cribbing and/or grading the work area with earthmoving equipment.

After seeing how challenging boom lift applications could be, it became clear there is a need to develop a boom lift with a more adaptable suspension. However, developing self-leveling technology comes with many design challenges that need to be overcome. 


Outside-the-box thinking

To accomplish an intelligent suspension system that can traverse uneven ground and tackle slopes up to 10 degrees, it is crucial to think outside the box of a traditional boom lift. The solid axles in the front and back of a machine cannot provide the flexibility and adaptability needed when operating over uneven ground. This traditional axle design offers minimal ability to adjust to uneven ground, often causing the boom to lean to the side and providing an uncomfortable operator experience, especially when driving at height. 

In addition to determining the best method to provide a practical self-leveling experience for operators on different grades, it is crucial to provide the operator with easy and intuitive guidance while using a boom lift with this technology. 

Another one of the challenges that needs to be considered when designing a self-leveling chassis is staying within the dimensional limits for shipping on a truck. Boom lifts over a certain length and height can create a situation that requires special permits for shipping, such as being classified as an oversized load. 

These challenges were translated into requirements that defined the system architecture, including the mechanical, hydraulic and controls, as well as user interface design, with the goal of allowing the operator to traverse uneven ground with full functionality while driving at height. 


A fully integrated solution

The self-leveling technology is designed to adjust the boom lift's chassis to the ground conditions (rather than adjust the ground conditions). The system provides a fully integrated solution to always make sure the machine automatically levels, even when driving the unit with the platform elevated. This increases a boom lift's capability on slopes from 0 to 10 degrees in any direction. The system allows the machine to traverse uneven surfaces while keeping the chassis level and improving traction capability on sloped ground.

This is accomplished with four independent axles with intelligent sensing technology enabling drive at full height while actively leveling the chassis. Independent axles mean that the new self-leveling technology differs from a traditional boom lift with a solid oscillating axle in the front and a fixed axle in the rear. In a JLG SLC machine, each wheel is attached to an arm which can act independently and separately adjust to the uneven ground as innovative sensing technology recognizes uneven surfaces. 


Optimized for the operator

After developing technology that would successfully self-level the chassis while moving over uneven ground and allow for operation on slopes up to 10 degrees, several key performance features of the machine were identified and optimized for operator ease. 

One of the system features is called Auto Level Mode, which the operator can select to automatically level the chassis when positioned on uneven or sloped ground. Auto level mode is always enabled while driving with the boom in an elevated position and is selectable by the operator with the boom stowed. This mode ensures that the operator is safely and smoothly moving across the terrain. 

Another unique feature is a High-Speed Mode, which allows for quicker movement from one spot on a job site to another. This allows the machine to move at the max speed only when the boom is in transport position and creep mode is turned off. To enable this, the machine is designed to center the chassis in a neutral position and with two wheels oscillating at any given time. This means that instead of the previous four independent swing arms, the machine utilizes two adjacent arms as a floating pair. The two opposing arms operate as a fixed axle, emulating a conventional boom lift. 

The final feature is Shipping Mode. When this is activated, the chassis is lowered or "squats down," and boom functions are limited. This feature was added in the design process to aid and conform with transport height requirements. The operator can easily place the machine in the Shipping Mode after it is loaded onto a trailer by pressing and holding the shipping mode button on the integrated user display. 

An integrated display in the control box is key to enabling intuitive operation and optimized operator guidance. The display on the self-leveling boom lift includes functions for Auto Level Mode, High-Speed Drive, and Shipping Mode and icons that communicate capacity zones, fuel levels, available functions, and any other information required for smooth and safe operation. 


Transforming work-at-height  

The development of self-leveling technology transforms the way people work at height by increasing productivity and enhancing safety best practices. Manual labor and time required to set up cribbing and/or grade the work area using earthmoving equipment are reduced, and so is the need for larger, higher reaching lifts as a backup to be able to position the machine further away from the work area in search for a level surface.

With the newly designed chassis, there is less platform movement during travel, improving operator comfort and reducing the risk associated with the movement of objects within and/or falling from the platform. Operators and occupants are more secure during travel due to the reduced bouncing of the unit as it traverses uneven terrain. 

JLG’s SLC technology automatically levels on grades up to 10 degrees when in self-leveling mode and provides two additional modes for versatility: High-Speed Mode for driving with the boom stowed at faster speeds and Shipping Mode, which allows the suspension to be lowered during transport. 

The 670SJ is the first JLG boom lift available with self-leveling technology. Learn more about this model and the technology behind it by clicking here

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