Patent GB-618595-A (GB)
Title: Improvements in or relating to bearings
IPC: F16C17/03
Filed: 1946-01-28
Abstract: 618,595. Bearings. CINCINNATI MILLING MACHINE CO. Jan. 28, 1946, No. 2692. Convention date, April 6, 1945. [Class 12 (i)] A bearing provided with pivotally mounted shoes arranged around the journal is also provided with a plurality of pockets circumferentially spaced around either the journal or in the shoe-carrying bush to which pockets fluid under pressure is supplied and from which such fluid leaks through a clearance whereby on slight radial displacement of the shaft the fluid pressures in the pockets are modified by the clearance changes so as to set up a restoring force. Fig. 3 shows the arrangement for a milling machine spindle supported in two journal bearings 10, 11, the first having an associated thrust bearing 16; Figs. 2 and 5 are cross-sectional views of the journal and thrust bearing portions. The housing 17 has secured thereto as by screws a bush 18 and an inner bush 19 with the latter held thereto by screws 20 and having pockets 21, 22, 23 cut therethrough to accommodate shoe members 24, 25, 26 pivotally mounted on the ends 27a, 28a, 29a of studs 27, 28, 29 screwed radially in the bush 18. To these pockets is supplied pressure oil delivered from a pump 30 through a passageway 34 in a side plate 35 secured to the outer bush 18 as by screws 110 and forming an element of the thrust bearing through an annular groove 36 on the side face of the thrust plate 37 secured on the shaft between a shoulder 114 and clamping nut 115, through borings in the bush 18 such as 44 and thence through throttling tubes 46, 47, 48 located in a circumferential groove around the outer bush 18 and respectively leading to the pockets 21, 22 23. This oil in addition to providing the necessary wedge-shaped oil film between the pivoted shoes and the shaft when the latter is rotating also provides a restoring force should the shaft be displaced radially since changes in the clearances between the shaft and the abutment areas 19a, 19b, 19c will in conjunction with the throttled supplies to the pockets 21, 22, 23 cause a build up of pressure on the shaft at the region towards which the shaft is displaced and a reduction of pressure on the shaft at the opposite region. The oil passing below the abutment areas 19a, 19b, 19c drains away respectively by grooves 53, 54, 55 to the annular end spaces 56, 57 and thence by borings such as 58 in the outer bush and 59 in the housing to the oil sump. The thrust bearing is shown arranged for taking up a normal thrust to the right; this is effected by the pressure oil leaking across from the annular groove 36 to arcuate grooves 122a, 122b, 122c, Fig. 5, of small area on the left-hand face of the thrust plate 37 and passing thence through cross-ducts 123, 124, 125 to arcuate grooves 126, 127, 128 of larger area on the right-hand face of the thrust plate. Axial displacement of the shaft is similarly compensated by buildup on reduction of pressure in the large arcuate grooves 126, 127, 128 arising on change of the oil escape clearance. When the shaft is up to speed, the oil supply pressure can be reduced since the wedge-shaped oil film at the bearing shoes will suffice for the automatic centring of the shaft.