Related Resources: gears

Design of Square Key and Keyway (Wood Ruff) Stress, Shear and Torque

Coupling Design	Kd
Fixed (tight fit) while loaded	1
Sliding Fit - Axial motion along the shaft when unloaded.	3
Sliding along shaft with loading	9

Application factors K_a

Application Factor Ka (DIN 3990-1)
Driving Component Loading	Driven Component Loading
	Uniform	Light shock	Moderate Shock	Heavy Shock
Uniform	1.0	1.25	1.5	1.75
Light Shock	1.1	1.35	1.6	1.85
Moderate Shock	1.25	1.5	1.75	2.0
Heavy Shock	1.5	1.75	2.0	2.25 or Higher

Characteristics of the Driving Component

• Uniform: electric motor, steam or gas turbine (small, rarely occurring starting torques)
• Light Shock: electric motor, steam or gas turbine (large, frequently occurring starting torques)
• Moderate Shock: multiple cylinder internal combustion engines
• Heavy Shock: single cylinder internal combustion engines

Characteristics of the Driven Component

• Uniform: Steady load current generator, uniformly loaded conveyor belt or platform conveyor, worm conveyor, light lifts, packing machinery, feed drives for machine tools, ventilators, light-weight centrifuges, centrifugal pumps, agitators and mixers for light liquids or uniform density materials, shears, presses, stamping machines, vertical gear, running gear
• Light Shock: Non-uniformly (i.e. with piece or batched components) loaded conveyor belts or platform conveyors, machine-tool main drives, heavy lifts, crane slewing gear, industrial and mine ventilators, heavy centrifuges, centrifugal pumps, agitators and mixers for viscous liquids or substances of non-uniform density, multi-cylinder piston pumps, distribution pumps, extruders (general), calendars, rotating kilns, rolling mill stands, continuous zinc and aluminium strip mills, wire and bar mills
• Moderate Shock: Rubber extruders, continuously operating mixers for rubber and plastics, ball mills (light), wood-working machines (gang saws, lathes), billet rolling mills, lifting gear, single cylinder piston pumps
• Heavy Shock: Excavators (bucket wheel drives), bucket chain drives, sieve drives, power shovels, ball mills (heavy), rubber kneaders, crushers (stone, ore), foundry machines, heavy distribution pumps, rotary drills, brick presses, de-barking mills, peeling machines, cold strip c, e, briquette presses, breaker mills

Key distribution factor K_m

Misalignment (in/in)	Misalignment of load factor Km
	1/2" face width	1" face width	2" face width	4" face width
0,001	1.0	1.0	1.0	1.5
0,002	1.0	1.0	1.5	2.0
0,004	1.0	1.5	2.0	2.5
0,008	1.5	2.0	2.5	3.0

Torque cycles	Fatigue life factor Kf
	Unidirectional	Fully reversed
1,000	1.8	1.8
10,000	1.0	1.0
100,000	0.5	0.4
1,000,000	0.4	0.3
10,000,000	0.3	0.2

Life Revolutions of Key	Wear factor Kf
10,000	4.0
100,000	2.8
1 000,000	2.0
10,000,000	1.4
100,000,000	1.0
1000,000,000	0.7
10,000,000,000	0.5