Q1: Define Key.
Ans: Key is a part of mild steel that is inserted between a shaft and a hub to connect them together.
It prevents relative rotation between the shaft and the hub and helps in transmitting torque.
Q2: Define Keyway.
Ans: Keyway is the slot or groove made in the shaft or hub to accommodate the key.
Q3: State the types of Keys.
Ans: The types of keys are as follows:
- ➔ Sunk Keys
- ➔ Saddle Keys
- ➔ Tangent Keys
- ➔ Round Keys
- ➔ Splines
Q4: Define Sunk Keys.
Ans: Sunk keys are the keys that are fitted half in the shaft and half in the hub.
They are commonly used for transmitting torque between the shaft and the hub.
Q5: State the types of Sunk Keys.
Ans: The types of sunk keys are as follows:
- ➔ Rectangular Sunk Keys
- ➔ Square Sunk Keys
- ➔ Gib Head Sunk Keys
- ➔ Woodruff Sunk Keys
- ➔ Parallel Sunk Keys
- ➔ Feather Sunk Keys
Q6: Define Rectangular Sunk Keys.
Ans: Rectangular sunk keys are rectangular in shape and are fitted partly in the shaft and partly in the hub to transmit power.
Q7: Define Square Sunk Keys.
Ans: Square sunk keys are square in cross-section and are used to connect the shaft and hub for power transmission.
Q8: Define Gib Head Sunk Keys.
Ans: Gib head sunk keys are rectangular sunk keys with a head at one end which helps in easy removal of the key.
Q9: Define Woodruff Sunk Keys.
Ans: Woodruff sunk keys are semicircular keys that fit into a circular recess in the shaft.
They are commonly used in machine tools and automobile shafts.
Q10: Define Parallel Sunk Keys.
Ans: Parallel sunk keys have parallel top and bottom surfaces and are used for transmitting torque between the shaft and hub.
Q11: Define Feather Sunk Keys.
Ans: Feather sunk keys are special types of sunk keys that allow axial movement between the shaft and the hub while transmitting torque.
Q12: Define Saddle Keys.
Ans: Saddle keys are keys that are placed on the shaft without cutting a keyway in the shaft.
They transmit torque mainly through friction.
Q13: State the types of Saddle Keys.
Ans: The types of saddle keys are as follows:
- ➔ Flat Saddle Keys
- ➔ Hollow Saddle Keys
Q14: Define Flat Saddle Keys.
Ans: Flat saddle keys have a flat bottom surface and rest on the shaft without any keyway.
Q15: Define Hollow Saddle Keys.
Ans: Hollow saddle keys have a curved bottom surface that fits on the shaft surface for better grip.
Q16: Define Tangent Keys.
Ans: Tangent keys are keys placed tangentially to the shaft and are usually used in pairs to transmit heavy loads.
Q17: Define Round Keys.
Ans: Round keys are cylindrical pins inserted into drilled holes in the shaft and hub to prevent relative motion.
Q18: Define Splines
Ans: Splines are multiple keys formed on the shaft that fit into corresponding grooves in the hub.
They are used to transmit high torque.
Q19: State the forces acting on the Sunk key.
Ans: The forces acting on the sunk key are as follows:
- ➔ Shear force
- ➔ Crushing force
Q20: Define Shearing of Key.
Ans: Shearing of key occurs when the applied torque produces a shear force that tends to cut the key across its cross-section.
Q21: Define Crushing of Key.
Ans: Crushing of key occurs when compressive forces act between the key and the hub or shaft, causing deformation of the key surface.
Q22: What is the difference between a Key and a Cotter?
Ans: The difference between key and cotter is as follows:
- ➔ Key is used to connect a shaft and hub to transmit torque.
- ➔ Cotter is used to connect two co-axial rods subjected to axial forces.
Q23: Name the stresses produced in keys.
Ans: The stresses produced in keys are as follows:
- ➔ Shear Stress
- ➔ Crushing Stress
Q24: If the material of the key and shaft are the same then what will be the length of key?
Ans: If the material of the key and shaft are the same, then the length of the key is equal to 1.5 times the diameter of the shaft.
