lawn mower confusion

[Mr Red]

My electric lawn mower was intermittently failing to start. I took it apart and made a circuit diagram which assumes a normally closed switch is included. The capacitor tested OK but it appeared to be leaking so I've ordered a new one. The confusing part for me is how the centrifugal switch on the motor rotor operates because there appears to be no electrical connection between the rotor and the stator. Can anyone enlighten me?

 

[Geoff1946]

I might be being thick but I can't see any centrifugal switch. It looks to me like the non-drive end of the rotor has a brake mechanism.
The motor is a capacitor run type, i.e. capacitor always in circuit
When it doesn't start does it make a humming noise ?
If NO look for a broken connection or dodgy control switch. (Very often the flex cores break internally close to where they enter the switch housing.)
If YES it could be the capacitor as you suspect, or sticking brake, or stiff bearings.

 

[Mr Red]

I might be being thick but I can't see any centrifugal switch. It looks to me like the non-drive end of the rotor has a brake mechanism.
The motor is a capacitor run type, i.e. capacitor always in circuit
When it doesn't start does it make a humming noise ?
If NO look for a broken connection or dodgy control switch. (Very often the flex cores break internally close to where they enter the switch housing.)
If YES it could be the capacitor as you suspect, or sticking brake, or stiff bearings.

Thanks for the reply. I think you are correct that it is not a centrifugal switch, it is a centrifugal brake in which case it makes sense that the capacitor is always in circuit.

The on/off switch works fine, I measured 240V at its output. There is no hum when the circuit is on.

I replaced the capacitor however I can't measure any resistance (it is open circuit) between one of the three wires attached to the coils and either of the other two. If there is no switch in this circuit I can only conclude that the windings of one coil have broken and that this mower is beyond repair.

Is there anything I've missed?

 

[Geoff1946]

If the motor windings are open circuit then yes I would think it probably scrap, BUT first check the connections if you can see where the enameled windings wire becomes the flexible tail. These are weak spots. There is also the possibility of a thermal fuse attached to the winding. probably at one of the above terminations. These are small, [perhaps 4mm diameter X 10mm long).