Week 1 - Tuesday Jan 7, 2025
What is due/expected on the 7th?
Nothing is due before class on the 7th but students can choose to watch any or all of the videos linked to in the next section.
Overview
- We will have a brief discussion on gears. Students will watch the Gears video at home during the week and take a quiz on the 14th.
- Engineering: Gears - Watch a 15 minute video before class and study the "Gears Quiz" below. Gear Types, Design Basics, Applications and More - Basics Of Gears https://tinyurl.com/ROBO2025-1
- Students will being building a simple mobile gantry crane "base bot". They can watch the video in/or prior to class on the 7th.
- Build a simple mobile gantry crane "base bot". See this video for an explanation of a gantry crane. https://tinyurl.com/ROBO2025-2
- We will have a brief discussion on My Blocks. Students are required to watch the "My Blocks" video at home prior to class on the 14th. Students will be expected to demonstrate proficiency with My Blocks in class or get assistance from a peer on the 14th.
- Programming: "My Blocks" - See this video for an explanation of My Blocks. https://tinyurl.com/ROBO2025-3
Gears Quiz
What is the primary purpose of gears?
A) To store mechanical energy B) To reduce friction in moving parts C) To transmit motion or power from one shaft to another D) To generate electricity
Answer C
What are the three primary usages of gears in a system?
A) Storing energy, reducing friction, and changing speed B) Speed ratio adjustment, torque ratio adjustment, and changing direction/motion type C) Power transmission, heat dissipation, and noise reduction D) Load distribution, wear reduction, and efficiency improvement
Answer B
Which of the following best describes a spur gear?
A) It transmits motion at an angle using spiral teeth. B) It is used to convert linear motion into rotational motion. C) It is the simplest type of gear with straight teeth aligned parallel to the axis of rotation. D) It uses magnetic fields to transmit torque without physical contact.
Answer C
True or False: Spur gears are commonly used in high-speed applications above 3600 rpm.
Answer False - Spur gears are typically used for low and medium-speed applications up to 3600 rpm due to noise issues at high speeds.
True or False: The main advantages of spur gears include complex design and expensive production.
Answer False - Spur gears are known for their simple design, low production costs, and easy maintenance.
What is the main advantage of helical gears compared to spur gears?
A) They operate more quietly and handle higher loads due to angled teeth. B) They can transmit motion between non-parallel shafts. C) They are commonly used in high-speed automotive systems. D) They are designed specifically for linear-to-rotational motion conversion.
Answer A
What is the key design difference between helical gears and spur gears?
A) Helical gears have fewer teeth in contact during operation B) Helical gears have teeth oriented at an angle to the shaft C) Helical gears can only be used with perpendicular shafts D) Helical gears have parallel teeth like spur gears
Answer B
Which characteristic makes helical gears better suited for high-speed applications compared to spur gears?
A) They have fewer teeth in contact during operation B) They generate more heat during operation C) They have better teeth meshing and operate more quietly D) They can only operate at low speeds
Answer C
True or False: Helical gears can carry more load than spur gears due to having multiple teeth in contact during operation.
Answer True - The angled tooth design of helical gears allows multiple teeth to engage simultaneously, increasing their load capacity compared to spur gears.
Bevel gears are specifically designed for:
A) High-speed linear motion applications. B) Transmitting power between shafts at intersecting angles. C) Applications requiring torque transfer without physical contact. D) Use in quiet, low-vibration systems.
Answer B
What is a unique characteristic of worm gears?
A) They can transmit motion in both directions equally well. B) They offer high-speed transmission with low torque. C) They provide a high reduction ratio with a compact design. D) They require a ring gear for proper operation.
Answer C
True or False: Worm gears are highly efficient with efficiency ratings above 85%.
Answer False - The main disadvantage of worm gears is their low efficiency which can be close to 15% due to high friction and associated axial stresses.
Hypoid gears are most commonly used in:
A) Differential systems to transmit motion between non-parallel, non-intersecting shafts. B) Heavy-duty industrial applications requiring straight-cut teeth. C) Magnetic systems where physical contact is undesirable. D) Lightweight systems that prioritize linear motion.
Answer A
True or False: Hypoid gears with larger shaft diameters allow for larger pinion diameters, making them suitable for high-torque applications.
Answer True - The larger shaft diameter in hypoid gears enables larger pinion diameters, which makes them well-suited for applications requiring high torque.
Which of the following describes the primary use of a rack and pinion system?
A) To provide quiet operation in high-speed machinery. B) To convert rotational motion into linear motion. C) To transfer power between two intersecting shafts. D) To reduce axial thrust in heavy machinery.
Answer B
True or False: A rack & pinion is a type of linear actuator that uses a linear gear (pinion) engaging with a circular gear (rack) to convert rotational motion into linear motion.
Answer False - A rack & pinion system actually consists of a circular pinion gear (not linear) meshing with a linear rack gear (not circular) to transform rotational motion into linear displacement. The question incorrectly swapped their descriptions.
An internal (ring) gear is characterized by:
A) Teeth that are angled for quieter operation. B) Teeth located on the inside surface of the gear ring. C) The ability to transmit motion between non-parallel shafts. D) Its use in linear motion applications.
Answer B
What is a defining feature of magnetic gears?
A) They transmit torque using physical contact between teeth. B) They convert linear motion into rotational motion. C) They use magnetic fields to transfer torque without physical contact. D) They are designed specifically for low-speed, high-torque applications.
Answer C
Which of the following is NOT a key property required for smooth gear operation?
A) Continuity of action - teeth must overlap during mesh to share the load B) Proper tooth spacing to ensure smooth load transfer C) Tooth shape must maintain correct angular velocity ratio D) The gear must be made of stainless steel
Answer D - The material of the gear, while important for durability, is not one of the fundamental properties required for smooth gear operation. The key properties relate to tooth geometry, spacing, and meshing characteristics.
Which of the following statements about gear trains and terminology is FALSE?
A) A gear train consists of two or more gears arranged in series B) In a meshed gear pair, the larger gear is always called the pinion C) The gear transmitting force is called the driver gear D) The gear receiving force is called the driven gear
Answer B - In a meshed gear pair, the smaller (not larger) gear is called the pinion. The other statements are all true.
If a driver gear has 20 teeth and a driven gear has 60 teeth, what is the gear ratio?
A) 1:3 B) 3:1 C) 1:20 D) 20:60
Answer A - The gear ratio is calculated by dividing the number of teeth of the driven gear (60) by the number of teeth of the driver gear (20), which equals 3. This means for every 3 rotations of the driver gear, the driven gear will rotate once, giving a ratio of 1:3.
Example calculation: Gear ratio = Driven teeth / Driver teeth = 60 / 20 = 3 = 1:3
Match the Following Gear Drive Modes with their Characteristics:
Drive Mode | Characteristics |
1. Gear Reduction | A) Input and output shafts rotate at the same speed with equal torque |
2. Direct Drive | B) Driven gear rotates slower but with higher torque (e.g., 3:1 ratio) |
3. Overdrive | C) Driven gear rotates faster than the driver gear |
Answers
- B) Driven gear rotates slower but with higher torque (e.g., 3:1 ratio)
- A) Input and output shafts rotate at the same speed with equal torque
- C) Driven gear rotates faster than the driver gear
Match the Following
Applications/Systems | Gear Types |
1. Hydraulic Pump | A) Hypoid Gear |
2. Manual Transmission | B) Bevel Gear |
3. Vehicle Differential | C) Magnetic Gear |
4. Truck Rear Drive Axle | D) Worm Gear |
5. Conveyor Belt | E) Spur Gear |
6. Car Steering System | F) Rack & Pinion |
7. Planetary Gear | G) Ring Gear |
8. Magnetic Gear Components | H) Helical Gear |
Answers
- E) Spur Gear
- H) Helical Gear
- B) Bevel Gear
- A) Hypoid Gear
- D) Worm Gear
- F) Rack & Pinion
- G) Ring Gear
- C) Magnetic Gear