How to Make a Slow Rpm Gear Drive a Faster Rpm Shaft UPDATED

How to Make a Slow Rpm Gear Drive a Faster Rpm Shaft

Gear ratios and chemical compound gear ratios

Working out simple gear ratios (two gears)

A feature often requested in my gear plan is that information technology should calculate and display the gear ratio.

The reason it does not have this feature is that the gear ratio is also the tooth count ratio (of the 2 gears), and that is a value that the user has to enter.

At left, the two meshing gears with 7 teeth and 21 teeth volition take a ratio of 7:21 (which is the aforementioned every bit one:three). That is to say, the 7-molar gear will turn 3 times for ever ane plough of the 21-tooth gear. The logic is simple, each gear needs to rotate past the aforementioned number of teeth for them to mesh, so the 7-tooth gear, having one tertiary the teeth, needs to turn three times equally much

Determining what gears you lot demand
Suppose you have a motor that turns 1200 RPM (revolutions per minute), and you lot demand to turn something at 500 RPM.
The ratio you lot need is 500:1200, or 5:12. However, elementary gears with only 5 teeth tend to run a fleck rough, so your best bet is to make (or obtain) gears with 10 and 24 teeth.

Determining compound gear ratios (multiple stages)

When a gear train has multiple stages, the gear ratio for the overall gearing system is the production of the individual stages.

For example, for the gear at left the blue gears are vii and 21 teeth, while the green gears are 9 and thirty teeth. Thus, the offset gear ratio is 7:21 and the second is nine:xxx. Multiplying the two together gives (7x9):(21x30) = 63 : 630, which is 1:10. And so the large green gear will make 1 plough for every 10 turns of the small blue gear.

Working out what gears you demand for designing multiple stage gearing
Any gear ratio that tin can be achieved past multiple stages of gearing tin can also be produced by single phase gearing, only for big gear ratios, the large gear can become unwieldy.

There are many ways to reach a given reduction with multiple stages, but how to determine what tooth counts to use for the gears?

Suppose we need a gear ratio that is i:eleven, and we desire the smallest gear to have no fewer than 10 teeth. We could do this with a 10-tooth and a 110-tooth gear. Lets write the ratio equally

ten:110

Now, let's imagine we put another gear in between those. Let'due south imagine putting a 35 molar gear betwixt the ten and the 110 molar gears. The gear ratio between the 10 and the 110 tooth gears will nonetheless exist the aforementioned, though the 10 and 110 molar gears will now rotate in the aforementioned direction, whereas earlier they turned in reverse directions.

With the 35-tooth gear in between, nosotros can at present think of now having a 10:35 molar reduction, followed by a 35:110 tooth reduction.

We can reduce the 35:110 to 7:22, simply if we don't want any gears smaller than 10 teeth, we need to double that to 14:44. And then nosotros tin can now make our 1:11 gearing with the following stages:

10:35   and  xiv:44

Total number of teeth between the two stages is 103 teeth, vs 120 for the original version. but more than chiefly, this gear set is smaller.

Common denominators are very important, and information technology may be necessary to pick a different intermediate molar count to make reduction possible.. If, yet, we wanted an 11 : 127 gear ratio, the only way to get that exact ratio would be with an 11 tooth and a 127 molar gear (or multiples thereof), because both are prime numbers that tin can't be factored.

On further consideration of the above 1:11 gearing example, we could accept done even meliorate if nosotros instead started with 1:11 every bit 12:132. We could then write this as 12:44 and 44:132, and the 44:132 is a 1:3 ratio, which nosotros could also make a ten:thirty. That would exit us with 12:44 and 10:30, which adds up to just 96 teeth total. We could likewise swap the two big gears if we wanted to. For example, 10:44 and 12:30 multiplied together also produce a ane:11 ratio.

Design case 2: Gears for clock face hour and minute easily

Suppose we want to make a 1:12 reduction for a clock. 12 factors into 4 and 3, and then we could practise a 1:iv and a 1:iii reduction. but let's see if we tin can make the two ratios closer to each other.

Let'southward multiply both sides by eight, so our 1:12 ratio becomes 8:96.
To go the reduction ratio for both gears, we want each gear ratio to exist virtually the square root of 12, which is almost 3.464. Now 8 * 3.464 is 27.seven. Then lets try 28 teeth for the intermediate gear.

So nosotros can write 8:28:96 or 8:28 and 28:96 We can dissever the right side by 4, so we get 8:28 and 7:24

It doesn't always work out and then nicely. Sometimes one side or the other doesn't take any mutual divisors, and then you may demand to try different values for the intermediate.

For a clock, the hours and minute hands take to be concentric, so both of these gear pairs have to accept the aforementioned shaft spacing. If we use the same tooth pitch for both gears, the shafts will not line up.

Using my gear generator program, I tin can but enter the shaft spacing, and the programme will recalculate the tooth size accordingly. I used viii cm for both sets.

I cut the gears out of some 10 mm thick plywood on the bandsaw.

If I place them on meridian of each other, the two sets of gears look almost identical, but they have slightly different ratios, and the teeth on one set are slightly larger.

A shaft through the larger gear on the right couples to the smaller vii-molar gear behind information technology, and the shorter "hours" hand is screwed directly to the large gear.

Now, if I had a timer motor that turned 1 plough per hour, I could make a actually big clock with these gears.

"Build a clock" is suggestion I oftentimes go. Perchance one of these days I will build one, maybe not. No need to suggest it at any charge per unit, because the idea has certainly occurred to me :)

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How to Make a Slow Rpm Gear Drive a Faster Rpm Shaft UPDATED

Posted by: markbarturponat1969.blogspot.com