# Questions tagged [gears]

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129 views

### Worm Drive Clutching Mechanism

Problem Description I have a project where I will need to be able to engage and disengage a worm drive (actually two of them). The worm drives are quite small. The worm gear is 49.2mm in diameter ...
44 views

### Efficiency of a planetary gearbox as a function of the lubricants viscosity

So I have a client that is asking about if they should switch from one lubricant to another in a planetary gearbox they have. The main advantage that this new lubricant has is that it has a much ...
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### Volumetric oil pump efficiency goes up when viscosity goes down?? Strange behaviour

Riddle me this : we are driving an external gear pump (this kind) at a fixed RPM. At start, when the oil temperature is low (and viscosity high), the volumetric flow is much less than when the oil ...
92 views

### Gear profiles (involute and root) generated by power skiving

@Involutius contributed an article on the equations that describe the root profile of gears which are cut by a trapezoidal-profiled hobbing tool. From that article, I was able to do a slightly ...
101 views

### What is the deflection of planet-ring Gear Mesh along the pressure line and the position of the Plant gear?

For a Sun-Planet mesh in a planetary gear train, there will be a deflection $\delta_{sn}=\delta_{s}-\delta_{n}$ along the pressure line and the position of the planet will be determined by $\psi_{n}$, ...
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### A round, plastic pinion in a lock?

I'm looking at a teardown of a Masterlock. The guts look like this What's strange to me is the black, plastic pinion that appears to be smooth and a strangely shaped cam: Here's the cam magnified: ...
• 1,033
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### What is the relationship for the curve of the non-involute portion of a gear (below the base circle)?

I'm in the works of writing my own gear program, but I've stumbled on something that textbooks and the internet don't seem to answer. A lot of the time, the dedendum of a gear cuts into the base ...
• 121
181 views

### Does it matter what direction a herringbone gear turns?

Obviously, the forces and pressures should mostly be the same, but just in reverse. But when play, flex, and such are accounted for, are there any subtle differences to having a herringbone gear turn ...
• 121
422 views

### Advice on spring launcher project

I found an ingenious design of a spring ball launcher on grabcad and I'm interested in adapting it to accelerate a $43.7 \mathrm{~mm}$ diameter, $45 \mathrm{~g}$ golf ball enough to reach \$65.5 \...
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131 views

### Gears with tilting shafts

I am looking for the following mechanism: A pair of gears initially in side-by-side arrangement. The shaft of the first gear is fixed to a first plate. The shaft of the second gear is fixed to a ...
• 121
90 views

### Optimum spoke shape for wheels made of solid material

Currently I am designing a bicycle sprocket to be laser-cut out of 3mm steel. Steel is heavy, so I want to make some lightening cut-outs, and I want to optimize the shape of the cutouts. I will ...
• 161
46 views

### I'm looking for the simplest way to increase rotational speed from 120 to 5,000 rpm for a light duty device

I'm currently designing a device and want to increase speed from 120 to 5,000 rpm. Device is lightweight, hand operated, free spinning, low torque in/out. Picture a cheap fertilizer spreader from Home ...
35 views

### Gearhead & 'teeth-track' to drive rotation of ringed encasement?

I am not an engineer, so apologies if this one is a bit of an ill-thought out... Can anyone show me an example of something like the following scenario: A small stepping motor driving rotation of a ...
62 views

### Performance of RC car under different gear ratio, measured data vs hypothesis

Assuming the driveshaft of the rear wheeled drive RC car follows the linear DC motor theory for stall torque and no-load RPM, also voltage supplied is constant and no inductance as well. Note: the ...
57 views

### Gearbox oil/grease leakage

Recently I encountered a problem of oil leakage from different driving systems SERVO gearboxes. The transmitted mechanical power ranges from 2 to 8 kW, while the motor speed (the gearbox input speed) ...
371 views

### Trouble with Base circle and meshing with spur gears

I am a novice who is trying to make some gears. I have followed the formula's but sadly something seems to go wrong and the gear's don't come out right. Below is some dimensions and pictures. Gear 1 ...
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62 views

### Efficient Gearing to Climb a Rope Vertically

I am trying to design a gearbox of sorts that would climb a rope from turning a gear (motor, handcrank, etc). The largest issue is that, while both the top and the bottom of the rope will be attached ...
• 121
77 views

### Measuring Helix Angle

What is the best way to measure the helix angle of a helical cut gear? I have a sun gear from a planetary set that I would like to have custom made but I'm not sure the best way to get the helix angle,...
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### Worm Drive Calculation

I have this setup: -Pully with a mass attached. -Worm gear drive to lower the mass with a constant speed. (Section A-A) Now if we look at the cross-section A-A, we can see the worm gear drive: ...
• 278
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### Gear design for symmetrical opening of two parts

I'm trying to build a lamp which has about 20 identical layers stacked on top of each other. There is a central spine and, on each level, a pair of arcs attached to the spine that are hinged and which ...
• 123
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### How to design CAD bevel gears from known outside diameter?

I'm working on a problem where I need to design and 3D print bevel gears to fit in the inside of a box and transmit a gear train around the inside corner, as roughly illustrated by the cross section ...
• 21
4k views

### Why is 14.5° a commonly used pressure angle in gears?

In gearing, according to Wikipedia and Dr. Rainer Hessmer's involute gear generator, the most popular pressure angles in the industry are 14.5°, 20° and 25°, with 20° being the most abundant. I can ...
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### Straight sided serration dimensioning

I have invented something and I need to have some external broaches made but I'm being asked for some dimensions I simply do not understand. I need 4 external broaches. They all have the same major ...
277 views

### Helical - Worm Drive

Is it possible to have a helical gear and a worm gear with the teeth angled the same amount, so that the helical gear can drive the worm gear, unlike a spur gear. Can the helical gear also move the ...
1 vote
83 views

### Calculating torque in planetary gearbox

It's my understanding that in a planetary gearbox, force moves through the system via four mechanisms: the ring gear, the planet gears, the planetary carrier, and the sun gear. I'm trying to ...
1 vote
166 views

### Rotational lock design for a landing gear of an aircraft

I want to design a rotational lock mechanism for the landing gear of an aircraft. It's function is to make sure the landing gear stays folded when the aircraft is on air and the landing gear's ...
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1 vote
37 views

### Sign convention for angular velocities in 3D gear train

Consider a Humpage gear train shown above. We are viewing the gear train from right and gear B is rotating in clockwise direction. If we consider clockwise direction as positive what will be the sign ...
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1 vote
71 views

### Gear Oil HP 85w-140 vs HP-140

I have a 4 Stroke scooter 150cc (SYM JET-14). Manufacturer recommends 85w-140 gear oil. The price difference between 85w-140 and single grade 140 is tremendous. Given that in my country and during ...
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1 vote
51 views

### What is a good approach on creating a custom robotics gearbox

I would like to put together a custom gearbox of the scale of around 50mmx30mmx30mm to fix a gadget that I am designing. My question is how should I approach producing this? Should I design components ...
1 vote
48 views

### AutoDesk Inventor Export Dimensions from Design Accelerator Generated Spur Gear

I'm working on modeling a turret-like mechanism in AutoDesk Inventor. Part of my design involves a rotating table. In order to accomplish this, I used the spur gear tool to generate a set of spur ...
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1 vote
24 views

### How is the equivalent spur gear diameter of a helical gear equal to (d/cos^2α)?

The book I've got says that the equivalent spur gear radius(re) = (Semi-major axis)^2/(Semi-minor axis) of the ellipse made by the cut-section normal to the teeth of the helical gear. There is no ...
1 vote
459 views

### How does this SpaceX Starlink ground station antenna's gear mechanism move it in both altitude and azimuth?

Ars Technica's Teardown of “Dishy McFlatface,” the SpaceX Starlink user terminal links to the YouTube video Starlink Teardown: DISHY DESTROYED! and a screenshot from there is shown below. There are ...
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1 vote
49 views

### What are the limits of small 3D printed gears?

How much tangential force should I expect a 10~20mm pitch diameter/1.5mm gear module 3D printed rack and pinion system to support without breaking nor sliding?
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1 vote
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### Can we reduce pitch of a lead screw to reduce backlash of the lead screw?

In gear design, the backlash is introduced in the design itself (not by tolerances of manufacturing) to allow free meshing of the gears. The backlash in the design can be minimized by reducing the ...
1 vote
47 views

### Building a custom indirect actuator, any thoughts?

I’m trying to create a custom indirect actuator, that is controlled by a microcontroller, for a custom robotics project. I have selected motor and gears (according to Fd = W = T2*pi) so that the ...
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1 vote
45 views

### Can we calculate the torque acting on the last gear determine teeth of the gears of the gear train in the below addressed manner?

The specifications of the generator is as follows: Efficiency- 70% Rated Torque- 0.56Nm Rated current- 14.3A Voltage- 24V Rotor shaft dimension- 1cm(diameter) The ...
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1 vote
123 views

I have used 250 watt DC motor, for DIY electric potters wheel. Motor rated with RPM 3300 and geared reduction to 330 RPM. The issue I am facing is wobbling of the motor head. This issue is with the ...
1 vote
47 views

### Bevel gear friction and inertia calculation

I want to calculate the friction and inertia between 2 bevel gears with straight teeth. I know how to calculate those parameters between regular gears with straight teeth. Is there any difference for ...
1 vote
61 views

### Efficiency of harmonic gear drives

Does anyone have application experience with harmonic gear drive efficiencies as opposed to planetary or parallel axis reduction systems? I'm looking into drives with about a 25:1 reduction, and it ...
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1 vote
147 views

### I need a mechanism/method to control a shaft that can rotate at different speeds. (faster clockwise and slower anti-clockwise)

I need to develop a mechanism - Where in I have a shaft that needs to rotate at different speeds. Lets say at a higher RPM clockwise and a lower RPM anti-clockwise. This shaft is attached to my ...
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1 vote
97 views

### The optical encoder resolution

The optical encoder has a code wheel with a single track of slots and two photodetectors. The photodetectors are positioned so that they produce signals with a 90 degree phase difference. I want to ...
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1 vote
31 views

### gear design.improving gear strength

For improving the gear strength, which one is better based on manufacture and economy? Increasing module or increasing N? With the same surface strength.
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1 vote
73 views

### Need bevel gear for SG90 servo motor

I am looking for a away I can convert the horizontal rotation into vertical, typically we use bevel gear for such thing. But I am using a SG90 servo motor for which I am struggling to get the correct ...
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1 vote
28 views

### Steel Worm/Steel Wheel vs Steel Worm/Bronze Wheel

I have a question regarding worm drives, specifically double-enveloping types: Do steel worm/steel wheel combinations last longer than steel worm/bronze wheel or steel worm/brass wheel combinations? ...
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1 vote
30 views

### What are the some of the best (dis)engagement mechanism for small gears?

I’m planing to build a robot out of gears. I was wondering what kind of (dis) engagement mechanism would be suitable for gears that are about 2.5cm (1 inch) in diameter. PS: preferably, (dis)...
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1 vote
130 views

### Reacting Propeller Torque?

A motor is used to drive a shaft that is geared through 1:1 bevel gears to a propeller. The shafts are mounted on bearings in a hard casing that is attached to a 2nd ground. I want to know if the 2nd ...
1 vote
358 views

### How to calculate bearing loads in a two stage helical gear box?

Here P, Q, R, S are the bearings and G1, G2, G3, G4 are four helical gears. The gear forces tangential(Kp), Axial(Ka), Radial(Kn) are known. All the distances are known. The forces acting on bearing ...
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1 vote
352 views

### Does the module of 2 meshing spur gears have to be the exact same value ?

Does the module of 2 meshing spur gears have to be the exact same value ? What is the allowable difference? So basically my module is off by 0 01 and my coworker made a model and it works. So I'm ...
1 vote