Patent GB-941306-A (GB)
Title: Improvements relating to power presses and other similar machine tools
Inventor: DEYKIN RONALD FREDERICK
IPC: F16D25/062
Filed: 1958-12-15
Abstract: 941,306. Friction clutches; clutch-brake combinations. HORDERN MASON & EDWARDS Ltd. Dec. 15, 1959 [Dec. 15, 1958; July 21, 1959], Nos. 40375/58 and 24996/59. Headings F2C and F2L. A fluid pressure operated friction clutch for a press or similar machine tool comprises driving and driven elements, between an electric motor driven flywheel 106 and a crank-shaft 102 on which the flywheel is journalled, one of which elements comprises a smooth surface of revolution, such as a disc or drum, and the other a unit or circumferentially spaced units each of which includes a body 122 and a fluid pressure actuated friction pad 133, the total pad friction area being substantially less than the swept area. As shown, the driving element comprises inwardly facing disc surfaces 111, 112 of spaced plates 109, 110, of cast iron, or high carbon or alloy steel, bolted to the flywheel 106 and the driven element comprises the bodies 122 secured in arms fast on the crank-shaft 102, each body housing two axially slidable cylindrical pads 133 of moulded friction material with metallic inclusions or of comparatively soft metal. Each pad is backed by a cylindrical mild steel or brass plunger 134 having a synthetic rubber sealing member 137. The pads may be fixed to the plungers by adhesive or bonding. Bolts 117 and bushes 116 spacing the plates 109, 110 permit radial air passage, for cooling, and permit pad-pressure produced wave-like distortion which serves to increase resistance to slipping. An odd number of arms, say 3 or 5, is preferred. Hydraulic actuating pressure is supplied to a chamber 140 between the plungers 135 from a stationary intensifier (not shown) through a pipe 149 and a rotary union 148, 147. The intensifier supplies hydraulic pressure of say 1000 lb/square inch from a pneumatic pressure of say 80 lb/square inch. A typical pad pressure is 1250 lb/square inch. A bleed duct 131 with a screw-in closure nipple 132 may be provided in the body 122. Slight axial flywheel thrust is taken by thrust elements 141 of synthetic resin such as nylon. On relaxation of fluid pressure only a light rubbing or intermittent contact remains between the pads and the disc surfaces so that re-engagement will occur with the minimum of pad movement and fluid flow. In the drawing of the first Provisional Specification (not shown) a disc having two outwardly facing surfaces forms the driven element keyed to the crank-shaft. The driving element comprises circumferentially spaced caliper shaped units bolted to the flywheel. Each unit includes one or two axially guided plates in each caliper limb, each plate having secured to its inwardly directed face a friction pad which may be circular. The pads and plates are axially moved to grip the disc through ball or knuckle joints by pistons in the caliper limbs. Hydraulic actuating pressure may be supplied to the limb cylinders from a flywheel mounted intensifier, or from an outside source of high pressure liquid through a flywheel mounted rotary union. In Figs. 1, 2 of the second Provisional Specification (not shown) a drum having a flange presenting inner and outer peripheral surfaces forms the driven element fast on the crankshaft. The driving element comprises inner and outer sets of units secured to the flywheel. Each unit houses a pressure fluid actuated friction pad, the pads of the inner and outer sets acting radially outwards and inwards respectively to grip the flange. The units are of equal number and arranged in a staggered manner. Combined clutch and brake means described in the first Provisional Specification may comprise clutch units and fixed brake units engaging two discs or a double flanged drum which flanges may be axial, conical or radial. The second Provisional Specification describes also clutches comprising an odd number of pads acting either radially outwards or inwards, clutches comprising sets of pads engaging axial or radial double flanges, means providing air flow, and body cylinders of square or rectangular cross-section. Specification 941,307 is referred to.