One of the most useful features on the new model was the provision of a dog clutch, contained within a housing immediately below the left-hand end of the headstock. The mechanism could be set to automatically disengage the saddle drive at any point in its travel - but only so long as it was travelling towards the headstock.

Instead of a single slot L-shaped  "banjo" arm - that restricted the size of the reduction ratio possible between headstock and leadscrew - on the new lathe the changewheels were carried in a pair arms arranged in V formation. Unfortunately only a single locking bolt--passing through the arm, and pressing the mounting boss--was used, a situation not corrected until 1921 when a bolt-through bracket was added at the back. One of the few components interchangeable between the original and Mk. 2 versions of the B Type were the changewheels - in this picture arranged in pairs on common studs for a 'compound- reduction train' to give almost the finest feed possible.

The single gear on a stud in the foreground occupies the slot used for introducing an extra gear into the train to cut left-hand threads.

The elegant (but unnecessary) horn handle on the end of the backgear shaft was replaced by a sensible but prosaic steel component.