Hi scagman2,
I am very aware that the engineering drawings of the clutch components are not easy to identify.
Here are the basic requirements of a mower clutch:
Be able to turn a V belt that drives the mower deck with the engine running.
Be able to stop the V belt from driving the mower deck with the engine running.
Provide an "clutch" that will allow the above mentioned to happen.
The clutch being the parts that engage/disengage as desired.
Provide the power/force needed to operate the clutch.
In the Ogura clutch assembly that we have on our Scag Tiger Cubs and many others machines, electricity is the power provided and magnetism is the force.
An electrical coil, when power is applied, provides the magnetic force to operate the parts of the clutch. This coil does not rotate with the crankshaft of the engine.
It is mounted on the lower triangular plate of the clutch assembly which has a bearing pressed into it. The rest of the clutch assembly rotates with the crankshaft with the exception of the deck V belt drive pulley, which also has a bearing installed in it. All of this is mounted onto the sleeve that pushes up against the pump drive pulley and is held in place by a keyway, key and the bolt that threads into the center of the crankshaft.
When the PTO switch is in the on position, power causes the coil to make magnetism which brings the two steel clutch plates together and turns the mower deck.
When the PTO switch is in the off position, the magnetism stops and the clutch plates separate stopping the mower deck from turning.
"Burnishing" of the clutch is when at lower engine RPMs, the clutch is operated intermittently to allow the friction surfaces of the clutch plates to wear into each other gradually so they will not slip during normal mower operation.
The six fingers shown in the Ogura diagrams are what flex when the clutch is engaged and also pull the V belt pulley when the PTO is on.
As these clutches are actually a clutch/brake, when the PTO switch is turned off, the brake engages to stop the clutch quickly. This braking action is adjustable by changing the air gap adjustments. Too small of an airgap will cause the brake to drag, to big of an airgap will cause clutch slippage and slower braking action.
The bottom line to the bearings is that the lower bearing turns all the time that the engine is running.
The pulley bearing turns all the time that the PTO is off and stops turning when the PTO is on as it now turns with the crankshaft.
Time for Mad Mackie to refill his adult beverage container!!!:laughing:
