Controls for multi spindle lathes

A multi spindle lathe comprising:

• a machine base;
• a spindle drum mounted on the machine base;
• drive means for indexing the spindle drum with respect to the machine base about an index axis in equal steps of m/360.degree., where m is a finite integer greater than unity, whereby the spindle drum is brought in succession into m different index positions;
• n spindles, where n is a finite integer greater than unity and not greater than m, the spindles being mounted in the spindle drum and defining respective spindle axes which are all in the same orientation with respect to the index axis, and each pair of spindles which are adjacently disposed about the index axis being angularly spaced about the index axis by an angle which is an integral multiple of m/360.degree.;
• a plurality of electrical circuits associated with the spindle drum;
• and
• a multi pole rotary electrical switch for controlling said electrical circuits and having a part which is fixed with respect to the machine base and a part which is rotatable with respect to the machine base about a switch axis and is arranged to index about said switch axis in synchronism with the spindle drum, whereby the rotatable part is brought in succession into m different index positions about said switch axis, the fixed and rotatable parts each having m.p cooperable contacts thereon, where p is a finite integer greater than unity, said contacts being arranged in the fixed and rotatable parts in respective circular arrays centered on the switch axis, each array being made up of m arcs subtending equal respective angles at the switch axis and each arc including p contacts, the contacts of each arc being similarly disposed so that at each of the m index positions of the spindle drum the contacts of the fixed part engage respective contacts of the rotatable part for controlling the electrical circuits respectively.