A spring stores elastic energy.
Deforming a spring creates a restoring force. Within a linear spring’s working range, force rises in proportion to deflection: F = kx, where k is spring stiffness.
Springs can work in compression, extension or torsion. Their materials and geometry determine their limits; the linear model does not apply to every spring at every deflection.
Stiffness connects force and movement.
Compressing it by 0.02 m produces 20 N of restoring force and stores 0.2 J of energy: E = ½kx².
This example starts from an unloaded spring. An assembled mechanism may already contain preload, so additional movement does not start from zero force.
Holding is different from stopping.
A friction brake presses surfaces together to resist relative movement. Holding a stationary shaft requires sufficient resisting torque. Stopping a moving system also requires energy to go somewhere.
During friction braking, mechanical energy becomes heat. A holding torque rating alone does not describe the brake’s ability to absorb repeated stops.
One common electrically released arrangement.
- Power removedSprings press the friction surfaces together.
- Release commandAn electromagnet opposes the springs.
- Brake releasedClearance permits rotation.
This connects the solenoid principles from Module 02 to mechanical force. The electrical supply releases the brake; the springs provide the applying force.
A lift brake is part of a coordinated system.
In many traction systems, the drive controls normal deceleration and the machine brake holds the car once stopped. Brake operation and monitoring are coordinated with the controller.
The machine brake is distinct from lift safety gear. Spring application alone does not prove that a brake can hold: friction condition, mechanical travel and the complete design still matter.
A closer look
Stored spring energy can remain when electrical power is absent. Understanding a brake’s operating principle is separate from dismantling or adjusting it; the installed design determines its specified clearances, forces and checks.
Check your understanding
Does a stationary brake holding torque continuously turn that torque into heat?
Reveal the explanation
Not through frictional sliding if there is no movement. During a sliding stop, energy is dissipated as heat. Electrical coils may have separate heating losses.
Further reading.
Connect this to motors.
See how electrical and mechanical principles meet in our introduction to how motors work.