Springs: Can they be used to conserve energy?

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Hankelec
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TL;DR
My initial question may have read, "Can a spring reclaim energy?" Reclaim spent energy? Certainly not. Can a spring reset a released energy, of which no purposeful energy was extracted, to a level near its original value?
Through mechanics, potential energy is released by the controlled falling of a suspended mass. At an idling condition, a one tonne mass is allowed to slowly fall. The pushing force of that mass is used to maintain a set rpm of a flywheel. The flywheel shaft drives an electric generator.

At a no load condition on the generator, very little energy is required to maintain flywheel rpm. If a significant load is placed on the generator, the generator will in turn place a load on the flywheel. To maintain set rpm, the braking system, controlling the rate of fall of the mass, will have to be backed off, which will present what appears to be a larger force to the flywheel drive mechanism.

The previous set up is a practical use scenario. What my question pertains to is, if a mass were to be used as a shattering device and allowed to free fall to the point of kinetic energy required to shatted a plate, the mass would contact, shatter, and continue falling. The resistance of the plate to move because of inertia and the power needed to shatter and pass through the plate would exact an instantaneous energy drop.

But rather than stopping the mass at that point, let the mass keep its forward momentum, eventually reaching a point of equilibrium of an expansion spring, whose stored energy will reverse the mass' direction and will return it to....what point of its original height? For calcs, use whatever values you deem practical. Mass = one kilogram or a thousand kilogram. I assume formula will all bear the same relationship, with maybe an iota of difference due to air friction.
 
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Can you post a sketch of the setup? And what is the relationship between these shattering plates and the spring you mention?
 
berkeman said:
Can you post a sketch of the setup? And what is the relationship between these shattering plates and the spring you mention?
I will post a sketch and explain the relationships of various components, just not at this moment. I have to tend to some tasks at this time that will eat up most of the afternoon but should be able to post this evening