Comparison of Rolling and Sliding Contact Bearing

Hydrodynamic Bearing

• Higher starting friction (torque)
• Load carrying capacity vary directly with speed.
• It is suitable for shock, fatigue.
• It is used for high load, high speed application.

• Hydro-static Bearing

• Load carrying capacity is independent of speed.

• Rolling Contact Bearing

• Poor damping capacity.
• Requires low starting torque.
• Under full running capacity, friction loss is more as compared to hydrodynamic bearing.
• Suitable for frequent start/stop applications
• It requires more radial space [but hydrodynamic bearing requires more axial space]
• It is preferred for precise location of journal axis.

Heat Generated in a Bearing

Power Loss Due to Friction is Heat Generated

Ploss = μWV

Here, W = Radial load, V = Rubbing velocity

• Heat Dissipation Equation

Hd = (Δt +  18)2 x A / K watt

Δt = Bearing temperature
A = l × d
K = 0.484 For unventilated bearing
= 0.273 For well-ventilated bearing