Machinery Lubrication

Machinery Lubrication March April 2018

Machinery Lubrication magazine published by Noria Corporation

Issue link:

Contents of this Issue


Page 38 of 86

36 | March - April 2018 | www . surfaces of the bearing run with the thinner oil (Figure 1). e bearings operated with the thicker oil did not show any signs of wear (Figure 2). The fear that the thicker oil would result in higher power dissi- pation proved unfounded. On the contrary, the gearbox with the more viscous oil exhibited fewer losses and a reduced operating tempera- ture. is can be attributed to better separation of the metallic surfaces in operation, which more than compensated for the slightly higher fluid friction. Spherical Roller Thrust Bearings in a Cooling Water Pump During tests on a large, cooling water pump – a concrete volute pump with a vertical shaft in a cast concrete housing (Figure 3) – the axial bearing at the drive end repeatedly exceeded its permissible operating temperature, resulting in an automatic shutdown. On closer inspection, the use of an unsuitable lubricant for this applica- tion was identified as the culprit. e oil in question was a pure hydraulic oil, which did not meet the bearing's requirements in terms of composition, i.e., additives or viscosity. The high measured operating temperature was the direct result of the metallic contact and resulting fric- tion, especially between the side faces of the rolling elements and the guide lips of the shaft locating washers (see Figure 4). is caused irreversible damage to the bearings' functional areas within a short time, in effect preventing reliable long-term opera- tion. e bearings had to be replaced at considerable expense. By changing to a suitably viscous oil selected for the applica- tion parameters and using spherical roller thrust bearings, a reliable sepa- ration of the contact surfaces and a low operating temperature were achieved. e plant has now been in fault-free operation since 2009. Deep Groove Ball Bearing in a Screw Pump e screw pump in this example delivers fuel – both heavy and light oil – to diesel engines. To allow the oil to be more readily pumped and injected into the combustion chamber, it is first heated. Conse- quently, the screw bearings are also exposed to the high temperature of the fuel oil. To realize the simple bearing concept required by the customer, i.e., a deep-groove ball bearing with integrated seals, a theoretical analysis of the setup was conducted. At the customer-estimated bearing temperature of 150 degrees C, a satisfactory solution was out of the question, as the lubricant's service life calculated based on this operating temperature and the asso- ciated life of the bearing would fall short of the required values. Following f urther consulta- tions, a temperature measurement Shaft ø 500mm Spherical roller thrust bearing (oil-lubricated) Housing Pump impeller Figure 3. Concrete volute pump with a vertical shaft K N O W w h e n t o s t o p a d d i n g G R E A S E P r e v e n t O v e r - L u b r i c a t i o n Monitor grease usage & costs with the Ultraprobe 401 Grease Caddy Pro. ® call 1-800-223-1325 -- Learn more: Visit us at Booth #729 BEARING LUBRICATION

Articles in this issue

Links on this page

Archives of this issue

view archives of Machinery Lubrication - Machinery Lubrication March April 2018