Qualcast Classic Petrol 35s drive problem

[F]

I've suddenly been getting some severe vibrations from my mower and it's stopped driving the blades and itself. Taking the cover off to reveal the drive shaft shows some pretty bad damage.

As I've not had the cover off before, I'm not sure how things should be arranged, but I'm sure there should be more metal in there! Should the metal 'prongs' on the outboard part be resting inside the rubber cutouts? If so, has the Allen screw allowed the cutout carrier to move inboard on the shaft?

Anyone care to advise on what needs to be adjusted and/or replaced?

Images at

[Bob Minchin]

Yes the prongs should be in the recesses in the rubber and not touching the other set. One half or other of the oldham coupling as it is called has shifted. Yes it could be the diecast part if the grub screws have come loose or the steel half could have moved. If it is the diecast part that has moved, then there will be tell tale marks on the shaft from where they first were fitted and then slipped.

[newshound]

Agreed, except that it's not strictly an Oldham coupling

Assuming that the right hand bit does not have freedom to move axially, it seems quite likely that the other bit has slipped because of a loose grub screw.

[F]

Thanks! Fixed! Neither Allen screw was particularly loose so the move apart must have been slow but steady.

And a bonus: having now mown the lawn within 36 hours of returning from a month long trip, I'm in Management's good books.

[conmathews]

Hi Have the the same problem I have loosened the grub screws but the diecast unit does not want to move am I missing something con

[conmathews]

Eureka a bit of wd40 and we are back in harness