Application Note: Disc springs in mechanical braking system
Braking systems for off-highway equipment are commonly designed to be hydraulically actuated. In most cases, braking occurs when pressurized fluid compresses stationary plates against plates that rotate with the drive shaft. The amount of friction between each set of plates controls the deceleration of the vehicle.
Without an additional fail-safe system, this design alone has limited reliability. If a hydraulic seal is compromised, or the hydraulic cylinder loses pressure for any reason, the brakes fail.
One solid mechanical back-up design uses SPIROL disc springs. Under normal circumstances, the hydraulic system holds a constant pressure on disc springs stacked in series. If pressure fails to be maintained, the stack of disc springs decompresses to actuate the braking mechanism.
Disc springs stacked in series.
A compression spring or wave spring is not capable of providing the force required (in the space available) to actuate the brakes. The reliability of this safety system is dependent on the consistent performance of disc springs. In this critical application, the disc spring's performance and level of predictability improves product quality and ensures overall safety.
SPIROL disc springs have a high capacity to consistently store releasable mechanical energy.
The conical design of SPIROL disc springs makes their spring characteristics and performance more predictable than traditional compression springs. Disc springs are also capable of providing more force in less space than a compression spring or wave spring.
They are commonly stacked in multiples to achieve application-specific spring rates: a stack in series provides less force over more travel; a stack in parallel provides more force over less travel. The precise tolerance of each individual disc spring provides unparalleled performance predictability when they are stacked (either in series or in parallel).
SPIROL disc springs also allow fatigue endurance to be predicted. Stress analysis enables the minimum cycle life of disc springs (singularly or stacked) to be calculated as a part of the application's design.
One way to start learning if this solution can help your application is to take a look at "Disc Springs" in SPIROL's Optimal Application Engineering portal. There, you can begin to address application types, load and deflection, temperature requirements, fatigue life, and more.
For a general overview, see disc springs on the SPIROL site here.
Read more SPIROL application notes -- including for coiled spring pins, solid pins, compression limiters, and inserts for plastics -- here.
Published April 2020
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