1. Chapter 6 Design of Keys, Splines and Pins
Key terms:
Keys
Splines
Keyway, keyseat
Hub
Crush
Pin

2. 6.1 Key Joints 1. Basic Concept A key is a fastening
inserted into the keyway
of two mating parts,
it is used to transmit
torque from a shaft to
a hub or vice versa.

3. 2. Types of Keys
Straight keys
Woodruff keys
Taper keys
Splines

4. 3. Straight Key Joints
1) Principles
clearance

5. 2) Types a. Plain flat keys 普通平键 (fixed joints)
C Key with one square and one rounded end
A Key with rounded ends
B Key with square ends

6. b. guided keys (sliding joints)

7. c. feather key joints (sliding joints)

8. 4.Woodruff Key Joints
Greater depth of the key seat in the shaft.

9. 5. Taper Key Joints
Gib-head taper key

10. Tangent Double-taper Key Joints

11. 6. Strength Calculation of Straight Key Joints
1)Failure Modes: crush, wear, snip
2)Crushed Strength Condition
T——torque
d——diameter of shaft
h——thickness of the key
l——working length of the key
[p]——allowable crush stress

12. 3) Steps for Selecting Straight Keys
a. According to the diameter of shaft, get section size
b  h;
b. Select proper key length L in key length series;
c. Check the Strength Calculation (if necessary); h L b

13. 4) Double-Keys Arrangement

14. 6.2 Splines Joints
Splines can be dealt as multiple keys which are integral with the shaft.
Splines are classified as: Parallel-sided splines
Involute splines

16. Advantages: 1) Greater carrying capacity; 2) Greater fatigue strength of a spline shaft; 3) More accurately centered and guided.
Disadvantages:
Requirements for special equipments and tools, which increase the manufacturing costs.

17. 6.3 Pin Joints
Pin for joining
Cylindrical pin
Taper pin
safety pin

18. Key Standards

19. The end Thanks!