Douglas flywheel clutches?

[cardan]

Can anyone help identify these three clutches? The outside diameter is about 8 1/2 inches.

Thanks

Leon

[Doug]

Leon,

The clutch release cam is for a late 2-3/4hp with flywheel clutch, such as the CW model. The one flywheel appears to have a small taper for the crankshaft, so I think that is also CW.

The other two look to have a larger bore for the crankshaft, so I suspect them to be EW model. According to the spares lists, the EW used 1/4 rollers for the sprocket bearing, where as the CW used 1/4 balls; and this would further help identify.

Flywheels clutch disks with the slot breaking out into two of the clutch spring holes are early. There was a washer with two tangs that went under the flywheel nut, projected through the slots in the flywheel, and engaged with the pressure plate to prevent it from slipping. Sometime during the EW era they dispensed with that feature.

They also used these clutches on some of the OHV machines like the RA, I.o.M./TT, OW, OB, and OC. But I am not sure what, if any detail differences they would have to the side valve clutch, other than the crankshaft taper was bigger than the 2-3/4hp, and more like the EW.

-Doug

[cardan]

That was quick! Thanks for the info. I think that they all have roller-bearing set ups (which would make them most likely EW), but I will check that, and measure up the tapers to see what's going on there.

Leon

[cardan]

OK: Two of the clutches have 25 mm tapers (at the large end), and one has a 20 mm taper. All three have roller bearings.

A TS crank has a taper about 20 mm, so I guess the smaller one is CW. Does an EW have a 25 mm shaft?

Thanks

Leon

[Chris]

    Another difference between the CW and EW clutches relates to the driven plate. On the CW the driven plate is a plain steel disk between friction linings riveted to the back plate and the pressure plate. On the EW the friction linings are riveted back to back on the driven disk.
    Also, where 1/4" balls are used in the CW the design is such that they provide a combined radial and thrust bearing. The EW clutch, having a roller race, utilises a separate thrust bearing in the form of a bronze/brass disc with holes having bearing balls captive in the holes by means of a ring staking each side. A bronze "Oilite" disc can be used in place of the original thrust bearing.  Chris.