Patent GB-1137135-A (GB)
Title: Change-speed power-transmission mechanisms
Inventor: STUART DUNCAN JAMES KEITH
IPC: F16H3/083
Filed: 1965-06-18
Abstract: 1,137,135. Change-speed control; cams. EDWARD WILLIAMS HOLDINGS Ltd. 25 July, 1966 [18 June, 1965], No. 25829/65. Headings F2D and F2K. A constant-mesh change-speed gear has stepped gears which are selectively clutched to a driven shaft by a key which is shifted axially by an hydraulic follow-up servomotor system. Gearing.-As shown two similar changespeed gears are provided for driving the feed shafts for the turret saddle and chasing saddle of a turret lathe and comprise stepped gears 12-16 fast on an input shaft 11 which mesh stepped gears 19-23 and 24-28 which are selectively clutchable to respective driven shafts 17, 18 by keys 31, 32 which are controlled by independent follow-up hydraulic servomotors. The driven shaft 17 is connectible to an output shaft 34 for the lead screw by a forward and reverse bevel gearing 35-38, and the driven shaft 18 is connectible to a turret saddle output shaft 50 by way of a two-speed countershaft gear 51-56 providing direct and reduced drive. The driven shaft 17 also drives a chasing saddle output shaft 42 through the reversing gear 35- 38 and a two-speed countershaft gear, the reverse bevel side wheel 38 being formed with teeth 38a meshing a step of a gear 40 which can be clutched to the output shaft 42 by a clutch sleeve 47, and which has a step meshing a stepped idler 43 having a step 45 which can be meshed by teeth 49 formed on the clutch sleeve 47. Control.-Identical servo systems control axial shifting of the clutch keys 31, 32, and the system for key 31 will be described. The key 31 is pivoted to the driven shaft 17 which is fast with a piston 60 in a cylinder 29 having a chamber permanently open to pressure 62 and another chamber selectively opened to pressure and exhaust through a valve 63 which has a control piston 67 formed with an exhaust port 72 and a control sleeve 69 which in the datum position shown isolates a servo chamber port 64 from a supply port 71 and from the exhaust port 72. Shifting of the control piston 67 to the right uncovers the exhaust port 72, and movement of the piston 67 to the left unseats the sleeve 69 from a fixed sleeve 66 and opens the cylinder port 64 to the supply port 71. The piston 67 is pivotally connected to an intermediate part of a lever 83 which is pivotally connected at its ends to the driven shaft 17 and to a rod 77 positioned by a cam 75 which is set manually to a position corresponding to a desired ratio. Setting of the cam shifts the piston 67 from its datum position, the consequent movement of the driven shaft 17 resorting the piston to its datum position when the desired ratio has been engaged. The mechanism controlling the key 32 is identical to that just described. The cams controlling the keys 31, 32 are fast with rotary valves which control the supply to cylinder units for shifting the clutch members 47, 55 These valves are each arranged to make the associated member take up one position in 180 degrees of the travel of the cam and the other position in the other 180 degrees of travel. Cam and follower.-The cam 75 has notches to receive a follower roller 78 at positions corresponding to the various ratios, the follower roller 78 being carried by a pivoted arm 79 and engaging a rim of a rotatable and axially slidable plug 80. Movement of the cam rotates the roller 78 which rotates the plug while it is being shifted axially. The control rod 77 is spring loaded towards the cam and has an adjustable abutment 81 engaging the end of the plug 80 centrally.