# What is Brake: Definition and 138 Discussions

A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction.

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1. ### I Prony brake calculation help (for determining engine horsepower)

I need some help here. I'm trying to determine how to use the numbers I'm getting for my pony break to determine horsepower at the axle of my engine. Right now I'm getting a reading of six pounds of torque, 4 in off of the center line of the axle at a rate of 30 rpms. Can someone help me...
2. ### Force of brake pads on a wheel

[Mentor Note -- thread moved from the technical forums to the schoolwork forums] I have a hollow-cylinder wheel model, braked with brake pads located at a distance d of the wheel's center axis. The brake pads have a contact area S. They are also forced towards the wheel with a pressure p. The...
3. ### Calculation of the rise in the temperature of a truck brake

The text gives the answer as 92ºC. The answer is arrived at by doing ##Q=Mgh=mc\Delta T##. But it is unclear to me if they are the same. I checked the coefficient of friction and it definitely seems to be considerable. Is the entire PE lost by the truck going to result in increasing the...
4. ### Help With Understanding Thrust Calculations (rifle muzzle brake)

Let me start off by saying I decided to post this in the aerospace engineering thread because it directly deals with thrust, even though it is not for a plane or similar. I have two equations that I can use to calculate the force on a baffle of a muzzle brake, Equation 1, from The Engineering...
5. ### Brake mechanism in a car and pressurised oil

(I must confess I couldn't get far, owing mostly to the term "an average distance (of 12 cm) from the axis". Axis of the (peached coloured) wheel at the center with the arrow pointing down? Is the arrow the location of the "axis" of the wheel? Let me see.) Objective : To find the oil pressure...
6. ### Engineering Find the brake torque in separately excited machine

Here's my attempt for part 1a: What I am not sure about is the direction, is it in the opposite direction (= - 458.37 N.m ) or it's positive? Thanks,
7. ### Automotive Cancelling effects on a larger brake rotor

Hello all, I am struggling to find out what exactly makes to have very little advantage in terms of cold stopping distance when you fit larger brakes on a car. Important note, the discussion is only regarding the braking power in the very first stop, before the heat starts to become a problem...
8. ### Calculation of Eddy Current Brake Force with a twist

All the equations I have seen have a component that is unknown. Also, if possible do let me know if there is a software I can use to model or analyze data related to eddy currents
9. ### Rotational Dynamics - Modeling brake caliper deceleration of a chassis

I am a junior engineer tasked with modeling the dynamics of a small research UAV after landing. The UAV has 3 tires, 1 on the nose landing gear and 2 on the rear landing gear. The rear tires are equipped with disc brake calipers. My coworker has explained that the simplified model (MODEL 1...
10. ### Handling brake failure/stuck accelerator in auto transmission cars

It's been a year since I was issued my driving licence. I have never driven automatic transmission cars, so my idea about them is very faint. I know that there is no clutch pedal, and one doesn't have to shift gears while driving forward - that's it. Last day, I was watching a TV show where...
11. ### Automotive Vehicle Parking Brake Test on a Slope [How Convert to a Flat Ground test?]

Vehicle Mass : 3 tonnes Manufacturer's instruction is to test vehicle's parking brake effectiveness is to engage parking brake on 30.96 degrees slope. If it holds, it is effective. I do not have 30.96 degrees slope & I want to replicate the same test on flat ground. I was thinking of...
12. I

### Why are 2/3 of my brake lights required to work by law?

In my State, the statute says 2 of 3 brake lights required. How is one brake light any brighter than 3 or 4? Is my perception of reality flawed? & though I say it is just as bright, when asked to give a reason why, I can not produce any answer. Is it because it is simply “there” or is it...
13. ### Automotive Placement of disc brake calipers for best performance

I thought that there was a standard placement for disc brake calipers on the front and back wheel assemblies for high-performance sports cars. I thought that I usually saw them placed at the back of the front wheels and the front of the rear wheels, but lately I've seen the opposite and other...
14. ### B Are Brake Pads Affecting My Car's Stopping Distance?

My guess is that distance Car A needs to travel until it stops is longer than car B (not by much), and so it the time. I also posted this question to reddit, if you want to check it out : I got the answer, but unsure of it's legitimacy.
15. ### I How can an asteroid get caught at a Lagrange point without a "brake"?

Talking about the Jupiter Lagrange points at 60 degrees only. Hard to imagine a scenario where an asteroid comes from outside or inside the orbit of Jupiter and stops at a Lagrange point. That's like tossing a cone on a table and trying to make it end up standing on its nose. Or make the nose...
16. ### Modeling Hydraulic Brake Behavior

Summary: Relation between deformed foil and friction force Good morning everyone, i have a small leaf or steel that is bent from one side by a Pressure of many bars. in front of the leaf there's a rotating disk, separated by the leaf by a small gap. this leaf, as it deforms, wins the gaps and...
17. ### Automotive Determining the Brake Caliper Force for a Car

Hi, I am trying to work out the calliper breaking force of a small motorsport car i.e. the moment force needed to be exerted at a given distance on the wheel to bring the car to a stop. I initial calculated the force using an equation which highlighted the specific capabilities of the brake...
18. ### Why must brake pads and rotors wear out?

I understand their job is to convert motion into heat, but can it not be done without causing wear on a regular passenger vehicle? Even if price is of no concern? Is it just we didn't find/create the ideal materials yet, or is there a scientific reason why they MUST wear out eventually? Bonus...
19. ### Automotive Exhaust brake for gasoline engines

Everything I've read about them has said they would be ineffective or have very minimal benefit due to lower compression on non-diesel engines and other factors. Yet I am aware of one that sold well in the '80's and '90's and was tremendously effective as a "mountain tamer" in the RV industry...
20. ### Automotive How to calculate brake power in IC engines?

Can somebody explain how to calculate brake power in IC engines ?
21. ### Braking force required on the disc brake pads

Hello, I'm currently working on the design of an e-caliper and I need to this effect to determine the linear force at which the pads have to be pressed against the disc to slow down a car swiftly. The result of my calculations is that the pad of a single front brake has to be pushed with a...
22. ### I Can a bicycle be tipped over by only applying rear brake?

Let's say I'm riding a bike at constant speed. Also assume that the person riding is rigid, no moving of the persons body, constant center of gravity. Assuming that there is sufficient friction between the tires and road. If I apply the front brakes, I will likely tip over. If I apply the...
23. ### B Why do softer brake pads stop a bike faster?

Why do softer brake pads stop a bicycle faster, and wear faster, and harder brake pads stop a bicycle slower, and wear slower? Thanks Much in advanced!
24. ### Automotive How to calculate hydraulic disc brake size using actuation force?

hello, How do i calculate brake size using force of actuation? im designing a hydraulic disc braking system (only one rotor caliper located in the middle of drive shaft) for go kart and using simple pascal law, i have calculated the force of actuation of the hydraulic brake that is the force...
25. ### Sizing hydraulic (brake) lines

On older GM cars, the brake lines are 3/16" from the front port of the master cylinder, splitting into two 3/16" for each front wheel, and 1/4" from the rear port of the master cylinder, splitting into two 3/16" for each rear wheel. This is the case for drum/drum or disc/drum configurations...
26. ### Dynamic Shear Force on a Brake Pad

I'm looking for a way to calculate the shear force applied to a brake pad from stopping ( a small engine brake pad stopping a fly wheel). I know shear stress is shear stress/ area , would this apply for a dynamic application as well? Would I need to calculate the force to stop the flywheel at a...
27. ### Car - brake locking, stopping distance

I have been reading quite a lot about the Physics behind car dynamics and I have gotten to a point which keeps confusing me, namely - brake locking. I understand brake locking as the situation when the wheels of the car do not rotate anymore but the car is still moving - this causes the tires...
28. ### The brake mechanism used to reduce recoil

Homework Statement The brake mechanism used to reduce recoil in certain types of guns consists essentially of a piston which is attached to the barrel and may move in a fixed cylinder filled with oil as the barrel recoils with an initial velocity v0, the piston moves and oils is forced through...
29. ### Difficulty with band type brake

Homework Statement [/B] What is the brake torque and the needed force to stop the drum. Photo of problem: https://gyazo.com/5c814dc6791b29362cc2835dacf7005a Data not on photo: Max pressure is 0.7MPa and friction coefficient is 0.2. Homework Equations T=(P1-P2)D/2 p=2P/bD dP-fdN=0 dN=Pdθ The...
30. ### Rotary Mechanical Brake System

Hi, I am looking into a braking system which can limit the rotational speed of a platform; the assembly consists of a fixed vertical shaft and a rotating outer tube (seated with bearings). The platform diameter is >5 times larger than the tube. I have looked into the typical band brake...
31. ### Calulating brake moment/torque for an airplane....

Homework Statement I'm working on this to further my understanding of parts used in an aircraft braking system. Using known weight, and constant acceleration determine braking moment for a tricycle gear airplane with two main landing gear brakes. Mass- 12,292 kg Acceleration: -1.4 m/s^2 Tire...
32. ### Eddy Current Brake Behavior (Accelerating From Rest)

Hey guys, So I'm interested in the application of an eddy current brake system as a high intensity shock absorber of some sort. The system would consist of permanent magnets concentrated on a stationary, non ferromagnetic metal. If a sudden, intense force were to act upon the non ferromagnetic...
33. ### Forces at rear brake caliper of motorcycle

Looking for some help with a rear brake caliper design. The rear caliper bolts to a carrier that slides onto and rotates around an axle. An torque arm (motorcycle term) or brake stay is required to prevent the caliper from rotating when the rear brake is applied. I have to figure a way to...
34. ### Fluid Dynamics question -- compressibily of brake fluids "oil"

As part of a racing community, there is a discussion going on that talks about compressibility of brake fluid. the Street car versions have a value of 6.5E-05 and the racing stuff is 4.5E-05 both at a pressure of near 5000psi. there is talk about the difference of the racing fluids which...
35. ### B So if we used the brake, the accleration would be?

*Neglect the friction between the car and the earth, but not the friction between the stuff inside the car & the interior surface of the car* For example, if we're moving with a car at constant speed and we used the brake to stop with constant acceleration, and the stuff inside the car included...
36. ### Piston force required (Disk brake system)

Hello everyone, I'm currently working on a project where we need to change the little manual wheel (shown by red arrow) and replace it by a cylinder (either pneumatic or hydraulic). Right now, when the manual wheel is adjusted by rotating it to the right, the contracting rim will come closer...
37. ### B Friends discussion: To brake or not to brake?

Hi there, we are having a tough discussion among friends concerning this topic: Imagine you are inside your car, stopped in the road. There is no obstacles in front of you, just plain road. Suddenly, because of the sound coming from the back, you realize another vehicle is going to impact you...
38. ### Using conservation of angular momentum as a braking system

Hello, I have a question about using the properties of conservation of angular momentum to provide mechanical resistance. Basically, I'd like to create a device that spins a disk similar to a gyroscope. The device has an external input that, depending on the configured orientation of the disk...
39. ### Educational Brake Caliper - Suggestions?

Hi everyone, My project is nearing completion and it will be a 3d printed brake caliper with the intent on it being for education although it may see a lot of use as just a neat desktop item for people. Either way, id like to have some documentation and possibly a quiz to accompany the...
40. ### Fokker 100 Brake Disc Actuator Main Landing Gear

Dear users, I have a problem with a calculation. I have got an assignment. For this assignment I have to redesign the brake actuators for the brake discs of the main landing gear of th fokker 100. I have forgotten how to calculate a force that goes sideways. The sideway forces are created when...
41. ### Brake Power, Engine Speed and bmep Relationship

I'm currently doing a report on Petrol Engines and I'm having a problem with my results not making sense. Am I correct in saying Break mean effective pressure (bmep) should increase as Engine Speed (rev/min) increases? My results do not reflect this and I don't understand why. I have attached...
42. ### Using KE in elevator-system to design brakes?

Homework Statement Hello! I am doing some rough design on an elevator-system and I have now come to the brake. Here is my system: The text is norwegian but "rdriv" in the first image is "Rdrivskive" in the second image and it's this wheel that is dragging the rope. The "Brems" is where I...
43. ### Automotive Automatic brake applying system

Hi fellas! I need to develop a system for a self driving car which involves automatically presses brake,clutch and accelerator when required.I am planning to use a servo for this purpose and have some trouble identifying the torque requirements! How much torque do i need?assume the lever...
44. ### Is Your Brake System Simulation Tool Accurate and User-Friendly?

Hello For the past 6 years I have been working (on and off) on a vehicle brake system simulation tool. It takes a lot of inputs about the car and the brake components, along with a rate of maximum lateral acceleration which is used to determine the amount of grip available. The model then...
45. ### Force required to bend sheet metal with a bending brake

I want to know the force required to bend a piece of sheet metal in a hand bending brake. The sheet metal is clamped down and then bent upwards to a desired angle. The action is performed in the video below . Let's say I wanted to bend a piece of .032" thick AL 3' long to 110° (given the brake...
46. ### Why would changing to a larger brake master cylinder decrease braking pressure?

Hi, I am in the process of restoring the brakes a 1974 Porsche 914 and upon reading up on a Porsche forum found a discussion about changing the original 17mm brake master cylinder with a 19mm one. A number of individuals indicated that doing so would reduce braking pressure and I was unclear as...
47. ### Force of a bar to stop a rotating cylinder

Hi, I'm having conceptual problems for solving this one. 1. Homework Statement I drew a picture of this problem, which should show up below. Lengths x,a and b were given in the original picture. A rotating closed cylinder is braked with a bar. Its brake shoe is pressed in respect of point B...
48. ### Hi guys, I am looking for some advice on animating or simulating brake system

Hi guys, I am looking for some advice on animating or simulating braking system of motorcycle. I have to make an animation or simulation of combined braking system for motorcycles, but I can't really find any softwares to do that. Even a circuit design would be which consist mechanical and...
49. ### Brake fluid volume calculation

Hello. I am in the process of calculating the brake fluid volume in the reservoir. I have a front disc and rear drum brake system. While the piston travel is clear for the disc brake, my question is related to the drum brake wheel cylinder piston travel. Assuming that the liner wear is 8 mm...
50. ### I need to build an electromagnet to provide 10mN eddy current brake

Hi I am building a motor tester, for that I need to build a variable load. For which I was planning to use eddy current brake with electromagnet. Please help me to build a electro magnet which can provide more than 10mNm load to a DC motor with rotating disc of 75mm in a RPM of 6500. I tried...