Clock springs, also known as power springs, or hair springs; are the oldest form of flat spring and the most common type in use today. They are made from strip material or flat rolled wire that is formed in to a flat, spiral shape. Clock springs are ideal for installations that are limited axially, but with more space radially.
The clock springs natural tendency to expand imparts a moment to either the arbor or case, producing usable torque. The torque generated is cumulative so that the force increases as the spring is wound tighter and decreases as it unwinds. They have many similarities with power springs, but have an operating range that is rarely more than one turn.
Their long rotational capacity, continuous torque, and Production range includes clock springs primarily of high-tensile spring steel or stainless steel grades, but also in soft material that is hardened and tempered after forming.
Technical information about clock springs
Clock springs are also torsion springs and are the direct opposite of torsion bars, which are made of spring wire. If we consider the shape of the space available for the spring function, the deflection of a clock spring increases as the number of coils increases, which means that radial space must be available. They are made of material with a rectangular cross-section, consisting of either flat-rolled wire or cold- or hot-rolled strip.
The load is introduced into the spring via legs, typically an inner radius bent inward at 90 degrees, which is fitted into a slot in a shaft. Further variations in leg shape are possible for the outer leg.
The manufacturing process of clock springs results in fairly pronounced ‘spiral’ shape, although this spiral is not vertical as with many other springs.
Clock springs are supposed to work without any contact between the coils and therefore without internal friction. This is only possible if the load is applied to the spring in the correct way. As the deflection and number of coils increases, coil contact should be avoided.
Special Features – Clock Springs
- High torque delivery per unit of deflection
- Relatively low cost
- Normal residual stress
- Wide assortment of materials can be used
Cold forming maximum material thickness 5,00 mm
Hot forming maximum material thickness 12,00 mm
Custom made clock springs
In addition to our stock of springs, Alcomex also produces customer-specific, custom made clock springs. This could mean different materials, dimensions and finishing.