Counterbalance Technology Lightens the Design Load

January 27, 2017 Rachel Pilgren-Kane

Counterbalance technology offers consistent operation and can help reduce fatigue and improve operator efficiency during the routine opening and closing heavy doors – restaurant appliances such as convection ovens are one example.

Lou Mintzer, Business Development Manager, Counterbalance, Southco, Inc.

From an office copier’s lid to doors on convection ovens and other cooking appliances used in restaurant kitchens, there is a surprisingly wide range of lids, hatches, covers and other panels that need to be opened and shut constantly, on a daily basis.

In applications where the end user must move and position heavy lids, panels and doors, it is essential that careful consideration be given when selecting a solution that not only enables easy lifting, but helps reduce strain or injury caused by repeated use or over-lifting. In many cases, successful appliance and industrial design largely depend on the incorporation of solutions that improve end user operation and address safety concerns.

Counterbalance torsion spring systems offers an innovative solution to this challenge – a technology that is reliable, long-lasting, easy to integrate into a wide range of devices and applications, and offers both functional and aesthetic advantages to enhance the long-term value and performance of the systems where these systems are used.


What Is Counterbalance Technology?

Counterbalance systems neutralize the weight of the door being moved, with minimum effort to open it fully, and minimum effort to move it into the closed position. This allows heavy doors and other fixtures to be moved with greater ease and less physical effort. They incorporate heavy-duty torsion springs that store energy when the door or fixture is closed; upon opening, the energy is released and the effort to move the door to a fully open position is minimized.

Similar to counterbalance systems, many people use an assisted or aided device of some type to lift or move an application every day, often without even thinking about it. For instance:

  • Engine hoods and rear hatchback doors of automobiles
  • Office building and commercial entrances with large, heavy glass doors
  • Office desks that can be raised and lowered for standing or sitting use
  • Residential garage doors – older, smaller models have spring mechanisms; larger, more recent doors have electric motors

Some of these devices have doors or lids that weigh only a few pounds, while others can weigh more than 100 pounds. What they have in common is routine or repetitive movement of loads – with enough weight or resistance from gravity through the full range of motion to have a noticeable effect on the end user.

Southco’s Counterbalance series combines assisted lifting force, positional stability through the full range of motion for opening and closing to make equipment operation safe and reliable. Counterbalance systems are engineered specifically for controlling the exact weight of heavy door and panels, allowing them to be lifted and positioned with ease.

Other Assisted Lifting Solutions

Designers do have a range of options to consider, in addition to counterbalance hinges, to neutralize the weight of heavy doors or panels. For some applications, such as manufacturing machine enclosures, powered assist devices – either using electric motors powering a screw drive or a prop rod – and hydraulically-powered lift assist devices are used. These options require multiple parts, and need power supplied to them as well as regular maintenance, so they are typically better suited to very specialized applications or settings.

The most commonly used lift assist devices are gas springs. These are heavily used in automotive applications such as rear hatchback doors. A gas spring, unlike a typical metal spring, uses a compressed gas, contained in a cylinder and compressed by a piston, to exert a force.

Their widespread use makes them easy to integrate into many applications requiring assisted lifting; however, gas springs do have certain functional drawbacks:

  • Because they use gas to supply force, they are temperature-sensitive; on a hot day, the gas driving the spring is more active, which can cause the door to “pop” up unexpectedly and be more rigid when trying to close, with the reverse being true on cold days.
  • Gas springs use seals to hold the gas in the cylinder; dirt, condensation or other contaminants that get into these seals can degrade their performance and potentially lead the gas spring to fail.
  • Due to the way gas springs work, they need two mounting points and need to be positioned at high angles; which can complicate installation in limited space applications.


Reducing operator fatigue with counterbalance systems

In comparison, counterbalance technology offers consistent operation and inherent advantages that make it a good fit for a variety of applications. For applications where operators are routinely opening and closing heavy doors – restaurant appliances such as convection ovens are one example – counterbalance technology can help reduce fatigue and improve operator efficiency. For instance, a door with a non-counterbalanced symmetric torque hinge may require 2.3 kilograms (kg) of effort to open from fully closed to 90 degrees open. By utilizing a counterbalance system, the energy required to open the door can be reduced to 0.9 kg.

In many retail food operations, such as fast food, convenience stores and more upscale family-style restaurants, these types of appliances are in heavy, constant use. Unlike an oven or microwave used in a residential setting, it’s not uncommon for some convection oven doors or panini press covers to experience more than a million open-close cycles within the first two to three years in use, exposing users to potential operator fatigue.

Minimizing operator fatigue and reducing workplace risk are two key areas where counterbalance technology can be useful. A third and critical consideration, is safety. Counterbalance systems designed with constant torque allow the user to move a door or panel into any position and have it stay in place. This means that heavy doors – such as an 80-pound kitchen exhaust cover – can be opened with ease by anyone, and won’t accidentally close on the person operating it, if it isn’t pushed all the way into its full open position.


Counterbalance Design Flexibility

For many industrial applications, space is at a premium – and the compact mechanical design of counterbalance systems makes it much easier to fit into existing products as their design is completed. Many counterbalance solutions also feature an enclosed design, which reduces the risk of dust and dirt interfering with operation.

In addition to compact size, they are modular: Because it is not gravity-dependent, the counterbalance system can be configured to fit into an appliance’s existing design parameters. For example, the counterbalance assembly can be split to accommodate a left handed or right handed installation and can be cut then stacked to fit, inverted to fit, or mounted on the outside of the unit.

In applications where there is limited space or unique dimensions, the Counterbalance series offers flexibility in mounting patterns to accommodate various panel lengths and weight to provide consistent lifting of heavy doors and panels.

This unique flexibility accommodates new applications or can be retrofit into existing applications when better technology is needed or warranted. And because counterbalance systems are purely mechanical and have been proven to operate flawlessly for more than a million cycles, they add simplicity and reliability to modularity.

These advantages have led to the expanding use of counterbalance technology in applications including:

  • Transportation – external hatches and storage doors on RVs and buses, as well as fold-down bunks on passenger aircraft and trains.
  • Vending machines – counterbalance hinges on the racks that hold beverages or packaged products and are pulled in and out for refilling.
  • High-speed document handlers – with heavy lids and other access panels on machines for bulk document scanning.
  • Restaurant flip-up counter tops – high-end clubs and restaurants are using richer, heavier materials like granite and glass in their bars and counters; sections using these heavier materials are opened and closed all day long, so counterbalance hinges help ease the ergonomic load on busy wait staff and servers.


Using Counterbalance Technology to Enhance User Touch Points

Leading suppliers of positioning technology have recognized that every time an end user opens, closes or moves a hinged device, the individual is both exerting force and is experiencing a distinctive tactile experience. Counterbalance technology offers designers a valuable option to solve several ergonomic challenges by neutralizing the weight of doors and panels, enhancing user touch points and, thus, the impression they have of the appliances being used.

There are multiple counterbalance systems and configurations; the key is to determine the full usage case for each application – what ergonomic effort should be expended to open, position and close a door or panel, and what user feedback is needed to accomplish this motion effectively and on a repeatable basis. Industry leading suppliers have extensive experience working through these usage cases to help define the right counterbalance solution, and can provide in-depth expertise to cost-effectively select the best solution for each application. 


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