Calculating MA and Input Force with Spur Gears

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Questions and Answers

What is the purpose of a ratchet and pawl mechanism?

To allow continuous rotary motion in one direction only.

What is the velocity ratio of two gears with 20 and 10 teeth?

1:2

What is a cleat used for?

To secure rope or string and prevent it from slipping.

What is the mechanical advantage of a pulley system that can lift a load of 1500N with a force of 500N?

3 Signup and view all the answers

What is the purpose of an idler gear in a gear system?

To allow the driver and driven gear to rotate in the same direction. Signup and view all the answers

How do two equal spur gears rotate when meshed together?

In opposite directions. Signup and view all the answers

What is the purpose of a compound pulley system?

To gain a greater mechanical advantage than a simple pulley system. Signup and view all the answers

What is the function of a disc brake?

To slow or stop the motion of a moving object. Signup and view all the answers

What is the mechanical advantage of a single wheel movable pulley?

Greater than 0 (MA > 0) Signup and view all the answers

What is the main function of gears in a system?

To increase or decrease speed, change direction of motion, transfer movement, force, and speed, and multiply or increase turning forces. Signup and view all the answers

What is the purpose of a block and tackle pulley system?

To lift heavy loads using the advantage gained by adding multiple pulleys to the system Signup and view all the answers

What is the purpose of a system diagram in understanding the hydraulic jack?

To illustrate the input-process-output of the hydraulic jack. Signup and view all the answers

What is the mechanical advantage of a block and tackle system with two fixed pulleys and two movable pulleys?

4 (MA = 4) Signup and view all the answers

How does the block and tackle system reduce the amount of force needed to lift a load?

By doubling the number of pulleys, which halves the amount of force, but increases the distance pulled Signup and view all the answers

How does a pulley system work?

A pulley system works by attaching a load to a rope or chain that passes around one or more pulleys, and when the other end of the rope is pulled, the load is lifted. Signup and view all the answers

What is the formula to calculate the mechanical advantage of a pulley system?

MA = load / effort Signup and view all the answers

What is the difference between a fixed pulley and a movable pulley?

A fixed pulley has an axle mounted in bearings attached to a supporting structure, while a movable pulley has an axle in a movable block. Signup and view all the answers

What is the advantage of using a compound pulley system?

A compound pulley system increases the lifting force (mechanical advantage) available to lift the load. Signup and view all the answers

What is the mechanical advantage of a pulley system with a load of 500N and an effort of 250N?

2 (MA = 2) Signup and view all the answers

How does a single wheel fixed pulley change the direction of force needed?

It changes the direction of force needed and multiplies force. Signup and view all the answers

What is the advantage of using a single wheel movable pulley over a fixed pulley?

It can lift and move the object to be lifted from one place to another Signup and view all the answers

What happens to the force required to lift a load when the distance is increased in a pulley system?

The force is decreased Signup and view all the answers

What is the mechanical advantage of a single wheel fixed pulley?

The force you must pull with is the same as the weight of the object, and the distance you must pull the rope down to raise the weight up to the same height is the same. Signup and view all the answers

What is the purpose of bevel gears in a system?

To change direction of motion and transfer movement, force, and speed. Signup and view all the answers

Study Notes

Pulley Systems

A pulley is a grooved wheel with a rope or a chain which lies in the groove.
The load is attached to the rope which passes around one or more pulleys.

Types of Pulley Systems

Single Wheel Fixed Pulley: has one wheel and one rope, attached to a support above the load to be moved.
Single Wheel Movable Pulley: the pulley is attached to the load being moved, reduces the amount of effort needed to lift and pull the load.
Compound Pulley (Block and Tackle): a combination of fixed and movable pulleys, increases the mechanical advantage (MA) as more pulleys are added to the system.
Block and Tackle: used to lift heavy loads, MA = 2.

Mechanical Advantage (MA)

MA is the ratio of load to effort (MA = load/effort).
Example: load = 500N, effort = 250N, MA = 2.
MA > 0 for single wheel movable pulley and block and tackle.

Gears

Definition: wheels with evenly spaced teeth on their outer rim, attached to an axle that is turned by a power source.
Uses: increase or decrease speed, change direction of motion, transfer movement, force and speed, multiply or increase turning forces.

Types of Gears

Spur Gears: equal size, meshed together, rotate in opposite directions.
Unequal Size Spur Gears: velocity ratio = number of teeth on driven gear / number of teeth on driver gear.
Rack and Pinion Gear:
Worm Gear:
Bevel Gear:

Ratchet and Pawl

A mechanism that allows for a continuous rotary motion in one direction only.
A pawl is a device attached to a ratchet which restricts movement in a particular direction.

Cleats

A device used to secure rope on boats and harbour docks.
Types: Horn Cleat, Jam Cleat.
Controls the movement of rope or string, prevents slipping.

Hydraulic Jack

System diagram: input-process-output.
Study the diagram and notes of the hydraulic jack and draw a system diagram.

Revision Test

What is a pulley system?
What is a compound pulley system?
Determine the mechanical advantage of a pulley system.

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Description

Solve problems involving mechanical advantage (MA) and input force using equal and unequal size spur gears. Understand the direction of rotation and velocity of gears.