Gears

In this affiliate, you will revise spur gear systems and how they can be used to alter the direction, speed and turning strength of rotation. You will calculate number of revolutions, rotation speeds and turning forces.

You will too look at other types of gears, namely bevel gears, rack-and-pinion gear systems, and worm-gear systems. These other types of gear systems make it possible to alter the direction of rotation in means that spur gears cannot practise.

Management of rotation of spur gears

Counter rotation and idler gears

1. 1. How many teeth do each of these gears have?

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   2. The black gear is turned clockwise until the yellow dot reaches the position shown in Effigy 4. Draw arrows next to Figure 4 to show where the blueish and red dots will be.

      

   3. In what direction did the blue gear turn?

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   4. Through which part of a full revolutiondid each gear turn?

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The two blue and black gears in the above situation turn in contrary directions. This can as well exist described past proverb that the two gears counter-rotate.

2. The night blue gear on the left below is turned anti-clockwise through two thirds of a full turn. Point with arrows where each of the yellow dots will be afterwards.

   

3. If the red gear beneath is turned anti-clockwise, in what direction will the grey gear turn?

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4. In the state of affairs beneath, the red gear drives the blue gear and the blue gear then drives the gray gear. If the red gear is turned clockwise, in which management will the grey gear turn?

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5. If the blood-red gear in the above system makes one full plough, how many turns will the blue gear make, and how many turns will the greyness gear brand?

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Number or rotations of driver and driven gears

Suppose the carmine gear in Figure viii drives the small grey gear. The red gear has xviii teeth and the gray gear has 6 teeth. For every 1 tooth in the greyness gear, in that location are iii teeth in the crimson gear.

When a gear has made a full turn, you tin say it has made one full revolution.

1. If the red driver gear makes one full revolution anti-clockwise, how many revolutions will the grey driven gear brand, and in which direction?

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2. If the blood-red driver gear makes 8 total revolutions, how many revolutions will the grey driven gear make?

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3. How many revolutions should the red gear make for the gray gear to make 12 revolutions?

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4. In a unlike set of gears, the driver gear has xx teeth and the driven gear has eighty teeth. How many full revolutions will the driven gear brand if the commuter gear makes 20 full revolutions?

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Speed of rotation of driver and driven gears

Suppose the small gear in Figure 9 drives the big gear. The small gear has 20 teeth and the big gear has 40 teeth.

1. If the minor driver gear makes 12 revolutions in i minute, how many revolutions will the driven gear make in the aforementioned fourth dimension?

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2. If the small driver gear in Effigy 9 makes 40 revolutions in ane minute, how many revolutions will the driven gear make in the same time?

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   If a gear makes 40 revolutions in i minute, we say the gear turns at a speed of forty revolutions per minute. The abbreviation rpm is often used for "revolutions per minute".

3. Look at the situation in Figure 9 once more. If the driver gear with xx teeth turns at 80 rpm, at what speed will the driven gear with 40 teeth plough?

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4. If you want the driven gear in Figure 9 to turn at a speed of 120 rpm, how fast should the driver gear be turned?

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Gear ratio, rotational speed and rotational force

A road roller has a bigger engine than a sports automobile, but moves much slower.

To brand a heavy route roller motility, a large turning force needs to be practical to the wheels. If the output rotational speed of the wheels is much slower than the input rotational speed of the engine, then the output rotational force will be much bigger than the input rotational strength. A route roller uses a set of gears that changes the fast rotational speed of the engine into a very tedious rotational speed of the wheels, so that the rotational force at the wheels is strong enough to move the heavy road roller.

With a sports machine, a much smaller rotational strength is needed at the wheels, because the motorcar is low-cal. The fix of gears used to showtime moving a sports automobile also changes the fast rotational speed of the engine into a slower rotational speed of the wheels, but non as slow as with the road roller. So with a sports automobile, the wheels turn faster but with a smaller turning strength than the road roller.

1. Await at the ready of gears in Figure 12. The driver gear has 20 teeth and the driven gear has eighty teeth?

   Is this gear system increasing the rotational force or decreasing it? Explain your respond.

   

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Revision of what you learnt near gears in course 8

Look at the gear up of gears on the right. The big gear is the input gear, and the modest gear is the output gear.

Each gear is fixed to an beam, and the beam drives a fan. The speed with which the fan turns is called the rotational speed of the axle.

When a gear with many teeth drives a gear with fewer teeth, the driven gear turns faster, only with a smaller turning force than the driver gear.

When a gear with few teeth drives a gear with many teeth, the driven gear turns slower, but with a bigger turning force than the driver gear.

Gear ratio is defined equally follows:

1. Calculate the gear ratio of the prepare of gears inFigure 12.

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   Gear ratio and speed ratio is the same thing. It tin also be called "velocity ratio".

   You tin can write a gear ratio in different ways, for example "2 to one", "2:1" or just "2",

   Turning force is also called torque.

2. In Effigy 12, if the input axle is rotating at 120 rpm, at what speed is the output axle rotating?

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3. In Figure 12, which axle will turn with the greatest force, the commuter or the driven axle?

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Comparing turning forces on the input and output axles

In Affiliate seven you learnt how a organisation of pulleys can give you a mechanical advantage to make information technology easier to hoist up heavy objects. You lot will now investigate how a gear system can do the same, by irresolute a small turning forcefulness on the input axle into a big turning force on the output axle.

Look at Figure 14 below. The input (driver) gear has 9 teeth and the output (driven) gear has 18 teeth. A rope is wound around each axle.

Notation: Y'all will only consider axles with the same diameter in this chapter. When the diameters of the axles around which the ropes are wound are dissimilar, you also need to think about that to compare turning forces.

1. What is the gear ratio?

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2. For one total revolution of the input gear, how many revolutions volition the output gear make?

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3. If you lot pull the input rope downwards by two cm, how far volition the output rope be pulled up? Draw the vertical office of the output rope in the "position at the end" part of Figure 14 to show where the output rope volition be after you pulled the input rope down past two cm.

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4. Will the force exerted past the output rope be bigger or smaller than the force practical to the input rope? How much bigger or smaller?

   Hint: Think of the situation as if it was a pulley system. You already know the relationship between the input distance and the output distance.

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5. If you pull down with a strength equal to3 kg on the input side, how heavy a load tin be lifted on the output side? Write this below and also on Figure fifteen.

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Use the formula above to check your reply to question v.

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Consider other sets of gears with ropes around the axles, as you did on the previous page:

1. In a certain arrangement, the input gear has half-dozen teeth and the output gear has 18 teeth. If you lot employ 4 kg of forcefulness on the input rope, what is the heaviest load that can exist lifted by the output rope?

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2. In a certain system, the input gear has 12 teeth and the output gear has 30 teeth. If you want to lift a load of 75 kg on the output rope, with what force in kilograms must yous pull the input rope?

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3. A certain person tin only pull with a maximum force of 25 kg. That person needs to hoist loads of up to 150 kg. Design a gear arrangement that will allow that person to hoist the heavy loads. In others words, how many teeth should the input and the output gears have?

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parallel, but the shafts of the two gears in Figure 17 on the correct are at correct angles to each other. The gears in Effigy 17 also take a dissimilar shape to ordinary spur gears to make them work better at correct angles to each other. They are chosen bevel gears

Do y'all think bevel gears tin too be used to alter the speed of rotation? Explain your answer and give examples.

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Why is fast rotation needed to beat eggs properly?

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In a particular bevel gear gear up, the gear ratio is 1 to 12.

1. The driven gear in this gear set has eight teeth. How many teeth does the commuter gear have?

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2. How many revolutions volition the driver gear make if the driven gear makes 60 revolutions?

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3. How fast should the commuter gear turn to make the driven gear turn at 36 rpm?

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Suppose you want to buy a food mixer to assist you mix ingredients when you lot broil a cake. Which food mixer would require the biggest forcefulness to plough when you mix: the mixer with a ratio of ane:3 or a mixer with a gear ratio of ane:30? Explain your answer.

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What do you think is inside the shell construction in Figure 20, and why is information technology there?

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In which direction volition the gate move when the gear wheel is turned clockwise (equally seen from inside the gate), in Effigy twenty?

The gear wheel is chosen the pinion gear.

The straight bar with teeth is called the rack gear .

When something moves round and round, like a bike, the movement is called a round motion or rotation.

When something moves in a straight line, like a stone falling, the movement is called a linear move.

The gear bicycle is called the pinion gear.

The direct bar with teeth is chosen the rack gear.

Which role of a rack-and-pinion gear set rotates?

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Which role of a rack-and-pinion gear set moves in a straight line?

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If the altitude between 2 teeth on the rack is 3 cm, and the pinion has 18 teeth, how far will the rack move if the pinion makes one total revolution?

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1. How many teeth does the pinion gear of the steering system in Figure 24 have?

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2. What divergence will information technology brand to the car driver if the pinion gear is replaced with a bigger gear that has 27 teeth?

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If the wheel in Effigy 26 has 32 teeth, how many revolutions volition the worm have to brand for the wheel to make one full revolution?

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Does the toothed wheel plow faster or slower than the worm?

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If at that place are 18 teeth on the wheel, and the worm is turned at 6 rpm, how long will it take for the toothed bicycle to make one full revolution?

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If there are 18 teeth on the wheel, how fast should the worm be turned to brand the bicycle plow at 3 rpm?

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There is another useful thing about worm gears: the worm tin can plow the worm bike, but the wormwheel cannot turn the worm. That is why worm gears are used for elevators.

Imagine you are in an lift that is lifted by an ordinary spur-gear set and the power goes off.

Explicate what would happen and why.

You learnt about hydraulic car jacks in Affiliate 6. At that place are also other kinds of machine jacks. In the infinite below, brand a rough sketch of how a rack-and-pinion organization combined with a ratchet-and-pawl system can be used to make a car jack.