Chummy Starter Button

InsulationThe “Bacon Slicer” starter motor on our Chummy “Jane” was not operating consistently when the floor button was being pressed. Sometimes it worked and the motor span perfectly, on other occasions the motor gave no signs of life at all. With shorting out the switch the motor itself was found to function correctly so the fault was clearly within the foot operated switch. First the motor assembly was unbolted from the engine. Only two bolts  hold it in place. Then the three screws holding the foot operated switch is removed from the motor assembly. This done, and with a little care, the tubular rivets through which the fixing screws pass, may be squeezed up enough to prize the two halves of the switch apart. These rivets are not absolutely necessary as the screws hold the switch together firmly enough once installed however they do aid assembly so are worth retaining.  With the switch now in two halves the internal mechanism could be inspected. The contact disc and stub heads were all OK, slightly pitted but not at all bad. However the liner insulation was found to be disintegrating and a section had fallen away and getting between the contact disc  and contact stud stopping any electrical contact being made. To correct this some thin (1/16″) Tufnell sheet was used to replace the cut insulation material that had originally been used. A disc fitted into the bottom, which was drilled for the centre shaft and for the contact studs. When drilling the centre hole check that the spring passes through and the full travel of the contact disc available. Another strip of Tufnell was laid around the edge and all glued in place, ensuring that the internals of the box were completely insulated. With this quick and simple fix there was no longer any possibility of interference with the free travel of the contact disc and electrical contact was reliably made. With the switch reinstalled and the motor back in place – Job Done

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