Counterbalancing With Constant Force Springs

Constant Force Springs are commonly used to provide a counterbalancing effect for a product. This blog examines different ways to integrate a counterbalance into a design, emphasizing the use of constant force springs in the manufacturing of a counterbalanced unit.

What is Counterbalance?

Counterbalance, as defined in Webster’s Dictionary, states:

  1. a weight that balances another
  2. a force or influence that offsets or checks an opposing force

As stated in the first definition, when one weight balances another, it shows the characteristics of a counterbalance. In one option, a weight of equal mass to offset the weight of the component part. The diagram to the right shows that this is usually accomplished using a counterbalance pulley system, a cable and a weight.

In this design, the overall weight of the product increases by 5 pounds due to the addition of the counterbalance weight. Extra space is required to accommodate this system.

What Does a Counterbalance Spring Mechanism Do?

A counterbalance spring is a torsion spring system or mechanism that makes it easier to lift and support all types of heavy loads, including lids, covers, countertops, and equipment. Torsion springs counteract downward force and provide balance for user control.

Counterbalancing With Constant Force Springs

Constant force springs are most useful in applications where a consistent recoil force is required. The behavior of ordinary springs obeys a mathematical equation called Hooke’s law. Hooke’s law states that the force of a recoiling spring in the direction of recoil is equal to the distance of the spring’s displacement from equilibrium. In simpler terms, we look at how far the spring has been stretched – multiplied by a mathematical constant, the rate of spring. The spring recoils opposite to the direction it has been stretched.

Hooke’s law doesn’t affect constant force springs because their recoil remains constant across their entire range of motion. Their unique design consists of a thin, coiled steel ribbon that is at rest when fully rolled up. Constant force springs become charged with force when they are partially or completely unrolled. When released, the spring recoils, pulling the extended ribbon back and rolling up rightly. As the recoil force is mostly achieved nearest to the coiled roll, a constant force is maintained.

A constant force spring can be used in place of the weight system and is an example of the second definition of counterbalancing, which is a force or influence that offsets or checks an opposing force.

Using Vulcan Spring’s Conforce® counterbalance spring for this application dramatically reduces the added weight and space required to counterbalance the component. Our stock counterbalance spring SH10K33, for example, would work for 28” of travel. The weight of this spring is .07 pounds, which provides 5 pounds of force. The outside diameter is approximately 1.00”.

Other options, including a longer length of travel, can be customized to fit the application and requirements. The mechanical spring assembly could look like the diagram to the left.

Constant force counterbalance springs have many benefits over a generic weight system for counterbalancing, such as smaller space requirements and less overall weight. Purchase from our spring store. For more information, please contact us today!

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