A distinctive L shaped "banjo" arm carried the changewheels. Early nuts and bolts were rather "fuller" than the later slimmed down versions introduced as a material-saving exercise during the First World War.

A quaint Drummond custom was to leave the headstock oiler nuts without covers - allowing swarf and dirt to drop into the bearings. Here a conscious owner had made simple drop-in plugs to offer some degree of protection.
The oilers doubled as a bearing expanders; they were screwed in until lightly engaged with a slot in the bearing wall - and the bearings adjustment rings then turned until the spindle showed some drag . Screwing the adjuster fully in expanded the bearing out slightly against the tapered wall of its housing and gave the correct clearance.
The little nick in the edge of the largest pulley rim is to show the location of the slot into which the bull wheel locking pin engages.

The slotted arm protruding from the rear spindle bearing was provided to carry a stud on which a changewheel could be mounted to reverse the leadscrew drive - and so cut left-hand threads.