Weight compensation

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A weight compensation (also called a spring balancer) is a technical device to compensate the weight of moving parts by an opposing force, which can be generated by a counterweight ( ballast ), spring force, hydraulics / pneumatics or a drive. This creates a balanced resting position without outside interference.

use

A weight compensation is often used for the manual, vertical positioning of objects (e.g. blackboard), but also for inevitable movement with a drive in order to reduce the required driving forces or torques (e.g. elevator). There is no lifting work to be done during the movement, only the force for acceleration and braking has to be applied.

realization

If the masses do not change, a constant counterforce can be easily achieved using a cable with pulley and counterweight . The correspondingly larger total mass and the space requirement are disadvantageous. Solutions with special ribbon springs or conventional springs in combination with a gearbox (to compensate for the path-force characteristic curve), with which the desired, almost constant counterforce can be achieved over the entire path, are easier. A pneumatic or hydraulic cylinder operated with constant pressure also fulfills this requirement.

In the case of variable weights (e.g. tools and different workpieces), counterbalances can be combined with brakes in order to cover a range of forces ( hysteresis ). The disadvantage is the higher force required for movement.

Active systems ( handling devices ) are equipped with a drive and controller and hold the position of the object automatically, regardless of its weight. A desired movement (manual force from outside) is recorded via operating elements or sensors and the drive is controlled accordingly. The dynamics of the system determine its efficiency and ergonomics .

Examples

  • Counterweight: blackboard, elevator, ceiling lamp
  • Gas pressure spring : car tailgate, office chair
  • Ribbon spring: height-adjustable monitor, tool suspension by "balancer" at manual workstations (e.g. automatic screwdriver)
  • Coiled spring: desk lamp

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