How to Use a Counterbalance Hinge for Pivoting Loads

If you want to design a product with a heavy lid or door, it’s useful to research how engineers have solved similar problems with other products.

You don’t have to look far to find examples.

Grill lids, car trunks, tanning beds, deli display cases, and many more products use counterbalance hinges for pivoting loads. 

If you need heavy-duty lid support, chances are, counterbalancing is the way to go.

What Is a Counterbalance Hinge for Pivoting Loads?

A pivoting load is any load that pivots around a fulcrum. There are two main kinds of pivots:

• Horizontal – parallel to the ground, significantly impacted by gravity. Lids are a good example.
• Vertical – perpendicular to the ground, less impacted by gravity. Saloon doors are a vertical pivoting load. This type of pivot is less of a counterbalance and more of a spring assist for closing.

A basic pivoting load has you lifting and/or pushing the full load around the fulcrum. But with a counterbalance and/or spring assist system, the load returns to the original closed position, as in a saloon door. 

With a horizontal pivoting load, you can use a counterbalanced hinge to help with the load. For example, a lid may weigh 50 lbs., but with a counterbalance hinge and spring assist, you could design the lid to weigh far less than that!

How a Counterbalance Hinge for Pivoting Loads Works

A counterbalanced lid uses special geometry so that it can counterbalance a load. With the right geometry, you can reduce weight – and you can get very specific about how much weight you want to reduce depending on the design. 

For instance, you could reduce almost all of the weight immediately if you wanted to, but most products are easier to use if there is some sensation of weight at the handle.

Any hinge design guide will tell you that a counterbalance hinge requires mechanical means to amplify force. Usually, this works by using a spring that applies force on a moment arm – a big lever inside the mechanism. As the spring expands, the lever is designed to change so the force changes and the lid becomes easier to lift. 

In other types of counterbalanced hinges, the variable pulley method is used. The variable pulley method works by increasing or decreasing the size of the pulley as the spring expands. The rate of change helps to match the spring rate with the change in force due to gravity to provide a near-constant opening force.

Pivoting Load Hinge Applications

Counterbalanced hinges can be designed for a wide variety of applications, either to improve existing products or add an innovative touch to new products. 

For example, our team retrofitted a counterbalance system on a vacuum chamber to replace an old gas spring assist. Counterbalances are great for lab equipment that have extremely heavy components. 

Counterbalance hinges aren’t only used for pivoting loads. They’re also used in:

• Countertop pass-throughs
• Freezer doors
• Kitchen appliances
• Murphy beds
• Library and museum equipment
• Fold-out furniture
• Ergonomic office equipment
  
  

Hinge Design Partners for Every Industry

Designing a custom hinge all comes down to what the customer wants. Do they want a spring assist for a gradual decrease in weight? Or a lid that pops up a few inches when it’s unlatched? 

Whether you’re aiming for industrial lid support, heavy lid lift assist, or heavy-duty hinge design, motion control engineering can do it. 

Want to learn more about counterbalance hinges and motion control? Take a look at our informational e-book!

Editor’s Note: This blog was originally published in September 2020 and was updated in May 2022.