Sprag clutches
AssigneeRenold PLC
InventorBenjamin Duncan Oldfield
Life of this patent
Estimating the term…
Abstract
In a sprag clutch having individual energising springs, one for each sprag, in which the forces on the sprags during outer race overrunning give rise to only a small rubbing load between the sprags and the clutch inner race at all outer race overrunning speeds within a designed limit, without nevertheless lifting off the clutch inner race, thereby limiting wear on overrun of the clutch, the sprags and the springs are staggered whereby each pair of adjacent sprags of said ring of sprags are offset relative to one another axially of the assemblage, and likewise the pair of springs associated with them, the sprags being shaped and arranged to interengage with one another between the springs to limit the tilt of the sprags in the driving phase of the clutch.
Claims21
A sprag-retainer assemblage for use in an annular gap defined between confronting cylindrical surfaces of inner and outer races of a sprag clutch to transmit uni-directional drive between the clutch driving and driven race, the assemblage comprising an annular sprag retainer, a ring of sprags in the retainer, and, for each sprag an energising spring individual to the sprag for biasing the sprag into substantially line contact with the inner race of the clutch, by tilting the sprag about substantially a line of contact with the outer race of the clutch, with a component of spring force directed radially inwardly of the assemblage, whereby the centrifugal force acting on the spring during overrunning of the outer race of the clutch, in use of the asemblage, relieves the spring force on the sprag, the centre of gravity of each sprag being disposed close to or in the radial axial plane of the assemblage containing said line of contact between said sprag and the outer race during overrunning of the outer race of the clutch such that the centrifugal force acting on the sprag during overrunning of the outer race of the clutch acts in conjunction with the spring force on the sprag so as to maintain a small load between the sprag and the inner race on overrun of the outer race, at least within a predetermined limit of outer race overrunning speed, in which the sprags and the energising springs are staggered whereby each pair of adjacent sprags of said ring of sprags are offset relative to one another axially of the assemblage, and likewise the pair of springs associated with them, the sprags being shaped and arranged to interengage with one another between the springs to limit the tilt of the sprags in the driving phase of the clutch.
A sprag clutch comprising inner and outer races and at least one sprag-retainer assemblage disposed in an annular gap between the races and arranged to transmit a uni-directional drive between the clutch driving and driven race, the sprag-retainer assemblage comprising an annular sprag retainer, a ring of sprags in the retainer, and for each sprag an energising spring individual to the spring for biasing the sprag into substantially line contact with the inner race of the clutch, by tilting the sprag about substantially a line of contact with the outer race of the clutch, with a component of spring force directed radially inwardly of the assemblage, whereby the centrifugal force acting on the spring during overrunning of the outer race of the clutch, in use of the assemblage, relieves the spring force on the sprag, the centre of gravity of each sprag being disposed close to or in the radial axial plane of the assemblage containing said line of contact between said sprag and the outer race during overrunning of the outer race of the clutch such that the centrifugal force acting on the sprag during overrunning of the outer race of the clutch acts in conjunction with the spring force on the sprag so as to maintain a small load between the sprag and the inner race on over run of the outer race, at least within a predetermined limit of outer race overrunning speed, the sprags and the energising springs being staggered whereby each pair of adjacent sprags of said ring of sprags are offset relative to one another axially of the assemblage, and likewise the pair of springs associated with them, the sprags being shaped and arranged to interengage with one another between the springs to limit the tilt of the sprags in the driving phase of the clutch.
Dependencies are inferred from the claim text.