Patent ID: 6176783
Filing Date: 2001-01-23
Classification: F16F,F16M

Abstract:
A rotary drag device having first and second members rotatable with respect to one another, the first member having a plurality of closely spaced, thin-walled flexible annular plates peripherally mounted thereon forming annular first running faces and a viscous fluid filling the spaces between the annular plates, the second member having a plurality of segmental elements forming part-annular second running faces interleaved with the annular plates to slide between the annular plates upon relative rotation between the first and second members, further comprising fluid release means permitting a release of viscous fluid from between the annular plates as a fluid pressure rises ahead of the segmental elements as a relative speed between the first and second members increases, wherein, when the relative speed between the first and second members is below a predetermined speed, the rotary drag device operates in a viscous coupling mode where a drag force rises proportionally with increasing speed up to the predetermined speed and where the annular plates flex to allow the annular plates to approach one another accommodating for a loss of viscous fluid from between the first and second running faces via the fluid release means and, when the relative speed is at least the predetermined speed, the rotary drag device operates in a boundary lubrication mode where the drag force is substantially constant with increasing speed over the predetermined speed and where a reduced amount of viscous fluid remaining between the annular plates provides boundary lubrication between the first and second running faces.