Improvements relating to polishing or like apparatus

1,010,437. Polishing. CHAPHONE ENGINEERING DEVELOPMENT Ltd. Sept. 22, 1964 [July 24, 1963], No. 29245/63. Heading B3D. [Also in Division Fl] Polishing or like apparatus comprises a rotary polishing unit, a spindle to which the unit is attached and means to cause axial movement of the spindle and unit relative to work to be polished, said means comprising two fluid-operated jacks each having a piston member and a cylinder member, one member of one jack being rigidly joined to one member of the other jack to form a pair, the cylinder members being interconnected for fluid flow so that, upon admission of pressure fluid to the cylinder members, the other members of the jacks not forming the pair move, relative to the pair, either towards one another or away from one another, the pair and said other members forming three relatively movable elements one of which is held stationary while the other two are permitted to move, the work being connected to one of said other members and the spindle and the unit being connected to the other of said other members. A honing machine for polishing the bores of tubes and having a stroke in excess of 15 feet comprises a long bed 10 at one end of which the work 11 is held in workholders 12. Main and auxiliary carriages 14, 15 run on guideways 13, the main carriage 14 carrying a long spindle 16 on the end of which the honing or polishing unit 17 is mounted. The carriage 14 carries means 18 for rotating the spindle 16. A first fluid operated jack 19 has its cylinder 20 secured to the bed and a second fluidoperated jack 22 has its cylinder 23 secured to the main carriage 14. The free ends of the piston rods 21, 24 of the jacks are connected by a block 25 secured to the auxiliary carriage 15. The carriage 15 carries a steady 51 for the spindle 16. The jack 19 has a piston 30 secured to the piston-rod 21 which has a bore containing a tube 27 spaced from the inner wall of the bore to provide an annular passage 28. The bore 29 of the tube 27 communicates with the cylinder 20 on the left of the piston 30. The passage 28 communicates, through a port 37 in the pistonrod 21, with the cylinder on the right of the piston 30. The left end of the passage 28 is closed by a ring 39 to which is secured a ring 40 providing a stop. The right end of the passage 28 is also closed. The cylinder 20 has adjacent its ends unions 52, 53 for the passage of pressure fluid into and out of the cylinder. The jack 22 is similarly constructed. The bore 29 of t