SACA Mechanical Power Transmission 4

Question 1

A planetary gear system has a sun gear with 20 teeth, planet gears with 40 teeth, and a ring gear with 100 teeth. If the sun gear is the input and the ring gear is fixed, what is the gear ratio?

Accepted Answer

6:1

Answer

With the ring gear fixed and sun gear as input, the ratio is (ring teeth / sun teeth) + 1 = (100/20) + 1 = 6:1.

Question 2

Which type of coupling is specifically designed to accommodate significant angular misalignment between two shafts?

Accepted Answer

Universal joint (U-joint)

Answer

Universal joints (U-joints) are designed to transmit torque between shafts at significant angular offsets, commonly used in driveshafts.

Question 3

In a flat belt drive, increasing the wrap angle of the belt on the pulley primarily affects which performance characteristic?

Accepted Answer

Friction-based torque transmission capacity

Answer

A greater wrap angle increases the contact arc, allowing more friction force and thus greater torque transmission before slippage occurs.

Question 4

What is the primary purpose of a backstop (holdback) device in a conveyor drive system?

Accepted Answer

To prevent reverse rotation under load

Answer

A backstop or holdback prevents the conveyor from running backward under load when the drive is stopped, protecting against uncontrolled reverse movement.

Question 5

Which gear geometry feature is measured by the 'pressure angle' in gear design?

Accepted Answer

The angle between the tooth profile and the pitch circle tangent

Answer

Pressure angle defines the angle between the tooth's normal force direction and the tangent to the pitch circle, typically 14.5° or 20° for standard gears.

SACA - Smart Automation Certification Alliance Practice Test

SACA - Smart Automation Certification Alliance Practice Test

SACA Mechanical Power Transmission 4