Q&A for How to Determine Gear Ratio

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If a 38 tooth gear running at 360rpm is driving another gear at 144rpm, what is the number of teeth on the driven gear?

Community Answer

T1*S1=S2*T2 where, T1=number of teeth on the driver gear, S1= angular speed on the driver gear, T2=number of teeth on the driven gear and S2=angular speed on the driven gear. 38 teeth*360rpm=T2*144rpm. T2=95 teeth on the driven gear.

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Question

How do I determine my gear ratio in my gear box?

Community Answer

If you can not see the gears you can mark the shaft and the start point on the gear box and count the number of times it revolves when you spin the other shaft one full rotation.

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Question

What is gear up and gear down?

Community Answer

Gear up is when you drive a smaller gear with a larger gear thus creating a faster RPM at the output but less torque. Gear down is to drive a larger gear with a smaller gear creating a slower RPM at the output but more torque.

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Question

How is gear ratio related to a gear train?

Community Answer

The number of teeth on your drive gear and on your driven gear determines the speed of driven gear.

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Question

What is breaking torque?

Community Answer

Breaking torque is the actual torque applied after all the engine inefficiencies (frictional torque) are removed from the torque the engine is calculated to produce (indicated torque).

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Question

How do I determine the speed ratio between two gears given the RPM of each?

Community Answer

Simply divide the 2 numbers the same way you would if you had the number of teeth of each gear.

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Question

Can we mesh a gear having 200 teeth with a 15-toothed gear? What is the affect of the gear ratio?

Community Answer

Yes. For each 1 rpm of the 200-toothed gear, the 15-toothed gear does 13.33 rpm.

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Question

If the wheels are spinning at 500 RPM, what would be the gear ratio?

Community Answer

In order to answer this question, we need to know the Drive shaft RPM. Once you know that, it's very simple math to determine the ratio.

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Question

How is the velocity of the gear ratio dependent on the radius of the gears?

Community Answer

For two gears to be driving/meshing against one another, they must have the same tooth design/pitch. So a gear with 80 teeth compared to a compatible gear with 100 teeth should have 80% of the diameter.

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Question

What is the connection between lpm and rpm?

Community Answer

Liters per minute = lpm (in terms of liquid). Rotations per minute = rpm (in terms of solid parts).

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Question

If the motor RPM is 3000 and it has 36 teeth in the gear, what is the RPM output?

Community Answer

You're asking an incomplete question. if the motor is rotating at 3000 RPM, we need to know the number of teeth attached to the motor output shaft. Once you have that, it will be a simple division problem to achieve your answer.

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Question

How can you determine the shaft speed of a motor (in RPM) without use of a tachometer?

Community Answer

Most manufactures have specifications for their motors that should list the RPM and input voltage.

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Question

Can I find the speed of both my gears combined without knowing one of the RPMs?

Community Answer

Yes, as long as you know the number of teeth on each gear and the RPM of either the drive or the driven gear, you can calculate the RPM of the other. First, determine the gear ration and then plug the numbers in for RPM. If you have a gear ratio of 4:1 and the RPM of the gear that rotates 4 times is 1000 RPM, then the other gear will be rotating at 250 RPM.

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Question

Does the gear ratio at the differential affect total gear ratio between input and output?

Community Answer

Yes. The ratio at the differential is a divisor that either increases or decreases speed in relation to the engine/drive shaft speed or RPM's. The gear ratio along with engine speed determines how fast the wheels will turn.

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Question

How can I calculate electronic gear ratios?

Community Answer

Divide the number of teeth of the driven wheel by those of the drive wheel.

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Question

How do I find the pitch line velocity?

John Liegl

Community Answer

Measure out one meter on the conveyor path and measure the time it takes to travel that distance. This will give you the speed in meters/time (seconds or minutes).

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Question

How do I determine gear ratio when I only have the input power and the output power?

Community Answer

If you have the input RPM and the output RPM, you may determine the ratio simply by dividing the two numbers. Let's say your input is rotating at 4 RPM and your output rotates at 1 RPM: the ratio is 4:1.

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Question

What RPM do you think could be achieved by spinning the gear by hand with a shaft connected to it.

Community Answer

You will not get good speed and unable to move conveyor belts. Speed and torque both are kept in mind during manufacturing.

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Question

How do I calculate the efficiency of a gearbox? What are the losses involved?

Community Answer

Gear box efficiency = work done at the input shaft divided by the work done at the output shaft expressed as a percentage.

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Question

If I have a motor turning at 3200 RPM with a pulley of 12 teeth, what's the number of teeth required to get the other shaft to turn at 100 RPM?

Community Answer

384 tooth gear, which would be a big gear. In this case you are going to need to have a series of smaller gears to reduce your final output to 100 RPM.

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Question

In a gear box, if the driver has 10 teeth and the speed of gear rotation is 100 rev/min, how do I calculate the speed of a driven gear with 120 teeth?

Κωνσταντίνος Γκόγκος Σακάλογλου

Community Answer

T1= Teeth of your driver gear (10), S1= Speed of your driver gear (100RPM), T2= Teeth of driven gear (120), S2= Speed of driven gear (x), T1XS1=S2XT2 => 10X100=S2X120 => 10X100/120=S2 => 1000/120=S2 => S2= 8.33 RPM.

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Question

What is meant by reduction ratio and trans capacity?

Community Answer

Gear reduction is a way to express gear ratio, and is read with the larger number first. For example, 4:1 is "four to one". The gear train reduces 4 revolutions of one gear to 1 revolution of another gear. A reduction ratio is just a way of saying the ratio, any number greater than 1 relative to 1. So 2 to 1, 3 to 1, 4 to 1, etc. In a typical automobile 5-speed transmission, the reduced gears are the 1st, 2nd and 3rd gears, sometimes called under-driven. 4th gear is drive and is 1 to 1 (no reduction and not over-driven). 5th gear (over-drive/over-driven) is normally 1 to 1.2. Capacity refers to the amount of transmission fluid a specific transmission holds and is required for optimal operation.

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Question

Will the speed increase as the gear ratio decreases? What will happen to the torque as a result?

Community Answer

The simple answer is that torque and gear ratios share a special relationship in that if you're going to use a gear set to increase the output RPM the torque decreases, and the opposite is true. When you use a gear set to decrease RPM, the torque is increased.

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Question

How do I find out the amount of teeth in a wheel when I know the gear ratio?

Community Answer

The only way to calculate that is to know the number of teeth of at least 1 of the gears. If you don't know that, than it's all speculation. The number of gear combinations to achieve the same gear ratio is virtually unlimited.

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Question

How do I calculate the module of the gear?

Community Answer

Pitch circle diameter (D) of the gear divided by the number of gear teeth (T). Module (m) = T/D.

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Question

What are the relationships between speed, torque, wheel size, and RPMs?

Community Answer

The answer will be: Speed 1/Speed 2=Wheel size 2/Wheel size 1=torque 2/torque 1 for speed, torque, wheel size, and RPMs respectively. RPM is used for measuring speed.

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