13-08-2012, 01:24 PM
Keys and Couplings
Key and Coupling.pdf (Size: 990.13 KB / Downloads: 33)
Keys
–Machine elements placed at the interface between a shaft and the hub of a gear, sprocket, or sheave to transmit torque
•Couplings
–Machine elements used to connect two shafts to transmit power
Forces and Stresses on Keys
Failure due to shear (shear stress)
•Failure due to compression (bearing stress)
Splines
•Splines
–Concept: multiple parallel keys
–SAE specifications: 4, 6, 10, 16 splines
–Torque capacity rating
SAE SplineStandard
•Known shaft diameter, D, and number of splines
•Decide type of fit (A, B, or C)
•Determine other geometry parameters (W, h, d) form the Table 11-4.
•Compute torque capacity from Table 11-5.
Example problems
•Design a belt system (v-belt) to transmit 20 hp from 1170 rpm to 400 rpm.
•The input and output of a chain system is 870 rpm and 250 rpm. Select chain and design layout to transmit 25 hp.
•Select a wire rope and pulley to lift 4000 lb load with the pulley installed at 60 ft off ground.
Bearing Examples
•Determine the size and material of a boundary lubrication for a radial load of 200 lb on 0.5”diameter shaft rotating at 300 rpm.
•Design a hydrodynamic lubrication bearing for an application of: 1200 lb radial load, 1.5”shaft diameter, and 1200 rpm shaft speed. Specify lubricant, operating temperature, power loss.