Inquiry (采购产品): Hydro-dynamic bearings Dear Sir / Madam. I'm studying for my engineering certificate and would appreciate some help with regards to hydro-dynamic bearing profiles. I thought that a 'lemon bore' and an elliptical bearing were of the same profile. This appears incorrect. I need to quantify some answers after trying to establish the difference if such a difference exists: 1) a 'lemon bore' bearing has the classic 2:1 ratio regarding horizontal to vertical bearing clearances? 2) a 'lemon bore' bearing must have two independent oil supplies because of its principle of operation whereas the elliptical bearing can have two or one? 3) the difference between the two bearing profiles is the way in which the bores are finally machined. "lemon bore' has a shim fitted between the bearing halves and keeps the bearing / machine centre at the same position relative to the two halves thereby creating the smaller vertical clearance and providing the two pad profile once the shim is removed and the halves are bolted together. On an elliptical bearing the bottom half is removed relative to the top, shim fitted and then machined. The bearing / machine centre is not longer at the centre of the bearing but is lifted by the thickness of the shim. The profile is such that the bottom half 'bedding' portion is not touched on final machining and material is removed from the top half and gradually decreases down towards the 'bedding' portion which is usually between 100 to 120 degrees . The finished product has a greater vertical clearance compared with the horizontal ? 4) a 'lemon bore' bearing establishes its stability with opposing preloads (i.e. bottom left and top right quadrants with CCW rotation). On an elliptical bearing there is only a single oil firm pressure profile typically at the bottom on a horizontal machine. It operation is similar to a plain cylindrical bore bearing ? 5) an 'under cut' is permissible on the top half of an elliptical bearing (not talking about a pressure dam) to increase bearing cooling. An under cut is not allowed on a 'lemon bore' bearing since it will loss its top preload? I would greatly appreciate answers to these questions since I am totally confused and have difficulty to differentiate between the two designs. Is there any web site you could refer with regards to a better understanding of hydro-dynamic bearings, in general. i once read the following: "The lemon bore (elliptical) bearing is a two-pad-fixed geometry bearing ............" (this statement is confusing). Regards Ian Mckenzie **** Hidden Message ***** Ian Mckenzie PO Box 18078 Sunward Park Boksburg1470 ZAF Company: VibraMac Phone: + 27 11 893 3680 Fax: +27 11 893 3680 E-mail: vibramac@telkomsa.net **** Hidden Message ***** vibramac@telkomsa.net
