Constant force springs’ unique qualities make them the perfect counterbalance for heavy moving parts.
One example is the door on a moving van. When you pull down an open door, it takes additional force to get the door going the first few inches–that’s because the spring’s full load (1.25 times its diameter) must be overcome. After that, the door slides down easily, with nearly constant force.
In addition to U-Haul doors, constant force springs are used in a wide variety of products. Some of the largest consumers are medical device manufacturers. MRI machines, dental X-ray equipment–and just about anything articulated and heavy–is equipped with constant force springs. Smaller constant force springs for medical devices are also part of syringes and drug infusers.
You’ll find plenty of constant force springs in everyday products as well: retractable key holders, retractable dog leashes, vacuum cleaner cord reels, seatbelts, window balance systems, interior blinds and point-of-purchase displays, to name a few.