The loading capacity of a bearing with an inside diameter of d mm, length 1 mm and load F Newton, is calculated as follows:
p = F N/mm2
d x l
With sliding speed < 1m/min, in intermittent operation, a surface pressure of half of the yield stress value of the material is permitted. With sliding speed > 1m/min, or continuous operation – the so-called PV value, Pressure Velocity, (N/mm²x m/sec) is used to determine maximum load capacity. For most bronze grades a PV value of 1.75 (N/mm²x m/sec) is permitted. An axial movement normally allows for a greater PV value.
For oil lubricated bearings a clearance of 1.5–2.5 ‰ of the inside diameter of the bearing is suggested. For grease lubricated bearings the clearance should be two times greater. For back-and-forth movement a clearance as small as possible is used (0.5– 1‰). In high temperatures the clearance should be bigger than normally.
The lubrication groove is very important in mounted bearings. Poor lubrication is often the fault of flawed lubrication grooves. In hydrodynamiclubrication the groove should not be situated in the load area. With radial reciprocating movement, place the grooves in the load area, the distance of the grooves should be <2 x angle of movement. Solid lubricants can be used in sliding speeds of under 0.5 m/sec
The coefficient of friction for the bronze bearing:
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