How It Works
The SSS Clutch shown above has an input
shaft with helical splines. Mounted on the helical splines is a sliding
component which has external clutch teeth, and external ratchet teeth.
When the input shaft and sliding component reach the same speed as the
output, they rotate until a ratchet tooth contacts the tip of a pawl
on the output clutch ring this prevents further rotation of the sliding
component relative to the output clutch ring (position shown).
As the input shaft continues to rotate, the sliding component will move
axially along the helical splines of the input shaft. When a ratchet tooth
is in contact with a pawl tip, the clutch engaging teeth are perfectly
aligned for engagement and thus will pass smoothly into mesh in a straight
line path.
As the sliding component moves along the input shaft, the pawl passes
out of contact with the ratchet tooth, allowing the clutch teeth to come
into flank contact and continue the engaging travel. Note that the only
load on the pawl is that required to shift the lightweight sliding component
along the helical splines.
Driving torque from the input shaft will only be transmitted when the
sliding component completes its travel by contacting an end stop on the
input shaft, with the clutch teeth fully engaged and pawls unloaded.
When a nut is screwed against the head of a bolt, no external thrust is produced. Similarly when the sliding component of an SSS Clutch reaches its end stop and the clutch is transmitting driving torque, no external thrust loads are produced by the helical splines.
If the speed of the input shaft is reduced relative to the output shaft, the torque on the helical splines will reverse. This causes the sliding component to return to the disengaged position and the clutch will overrun.
The SSS Clutch can continuously operate engaged or overrunning at maximum speed without wear occurring.
At high overrunning speeds, pawl ratcheting is prevented by a combination of centrifugal and hydrobodynamic effects acting on the pawls.
Where necessary, an oil dashpot is incorporated in the end stop to cushion the clutch engagement.
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Operating Principles of the SSS Clutch |
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