Patent GB-707243-A (GB)
Title: Improvements in or relating to lathe transmissions
IPC: B23Q5/12
Filed: 1951-05-02
Abstract: 707,243. Lathe details. BOEHRINGER GES., GEB. May 2, 1951 [May 3, 1950; Aug. 1, 1950], No. 10347/51. Class 83 (3) A headstock and feed device for lathes comprises a number of speed change sub-transmissions each optionally adjustable to one of a number of transmission ratios giving spindle speeds in approximately geometrical progression from a shaft to the spindle either by a belt drive or by a reduction gear (" all-gear") and is characterized in that an intermediate shaft of said reduction gear is geared to the spindle through a sub-transmission optionally settable to two ratios namely 1:1 and 1:n, (n being a predetermined number between 2 and 5) and is driven from said shaft at a reduced speed via a pair of speed-reducing gears governing the overlap between the " all-gear" drive and the belt drive. A feed gear box is driven alternatively either from a gear shaft of one of the subtransmissions or from the lathe spindle. An electric motor 12 may be clutched to a shaft 13 carrying gears 14 ... 16 and the drive passes selectively to either the sliding gear pair 18, 19, or to gear 20 all arranged on a shaft 17. The gear 20 is driven in reverse direction from a wheel 21. Gears 24, 25, secured to the shaft 17 transmit the drive to sliding gears 26 ... 28, on a further shaft 23 which thus has six possible speeds. Gears 29, 30, are secured to an extension of shaft 23 and engage selectively a pair of wheels 32, 33 on a shaft 31. Belt drive.-The gear 32 engages a gear 34 loose on a shaft 35 and the latter gear engages a sliding gear 36 on a shaft 37 when belt drive to the work spindle 10 is desired. This drive passes from shaft 37 through the equal diameter belt pulleys 38, outside the headstock casing 11 to the work spindle. The wheels of the gear train from the motor are so arranged that one of the possible trains gives a 1:1 ratio so that the maximum speed of the spindle is equal to the speed of the motor. The other trains give speed reductions, the steps of which are approximately in G.P. "All-gear" drive.-A gear 40 secured to the wheel pair 32, 33, on shaft 31 drives a gear 41 secured to the shaft 35, and a slidable gear pair 42, 43, transmits the " all-gear " drive finally through gears 44, 45, to the work spindle 10. The gears 42, 44, have the same number of teeth so that the overlap in speed range between the belt and gear drives depends upon the reduction ratio selected for gears 40, 41. The ratio in the example shown is 1:4 and results in six speeds of the belt and gear drives overlapping. The gears 40, 41 are easily changed in constructing the lathe to suit the speed range requirements of the user. Feed and screwcutting drives.-A feed gear-box 52 drives a lead screw 50 and a feed shaft 51. This box is driven from a shaft 55 through pickoff trains such as 53 or 54. The shaft 55 receives its drive either through the gear train 59, 58, 60, or from the train 62,. 61, 63, 64, for normal or fine feed respectively. The gears 59, 62, are secured to a shaft 56 which may be driven in three different ways. A compound gear 65 on the shaft 56 may be moved so that the shaft is driven either from a gear 68 on the belt-driven shaft 37 or from a gear 67 on the work spindle 10. A third drive is obtained from the shaft 23 through the gears 69, 70.