Bearing unit, drainage pump and hydraulic turbine each incorporating the bearing unit

A bearing unit comprising:

• a bearing;
• and
• a sleeve which is in slide-contact with said bearing, wherein
• either of said bearing and said sleeve made of a metal has a contact surface applied with a sprayed coating, the main component of which is WC, and which contains one or more elements selected from a group consisting of nickel, chromium and cobalt as a binder material thereof, and the residual is made of SiC or Si.sub.3 N.sub.4, or metal having a contact surface area applied with a sprayed coating the main component of which is WC, and which contains one or more elements selected from a group consisting of nickel, chromium and cobalt as a binder material thereof, and metal having a contact surface area applied with a sprayed coating the main component of which is Cr.sub.3 C.sub.2, and which contains nickel and chromium as binder materials or metal which contains SiC or Si.sub.3 N.sub.4 and the number ratio of blow holes contained in the surface of said sprayed coating and having a size of not smaller than 20 .mu.m is 15 per square millimeter or less.

A bearing unit comprising:

• a bearing;
• and
• a sleeve which is in contact with said bearing, wherein
• said bearing and/or said sleeve made of metal has a contact surface applied with a sprayed coating, the main component of which is WC, and which contains one or more elements selected from a group consisting of nickel, chromium and cobalt as a binder material thereof, and said sprayed coating is heated at a temperature of from 300.degree. C. to 550.degree. C. after said sprayed coating has been formed, said sprayed coating having a hardness of Hv 1000 or higher.

A bearing unit comprising:

• a bearing;
• and
• a sleeve which is in contact with said bearing, wherein
• said sleeve is made of metal having a contact surface applied with a sprayed coating, the main component of which is WC, and which contains one or more elements selected from a group consisting of nickel, chromium and cobalt as a binder material thereof, and the ratio W/D.sup.2 of weight W (kg) of said sleeve and the outer diameter D (cm) of the same is 0.05 or less.