A brake is a tool by way of which synthetic frictional resistance is utilized to a transferring machine member, with a purpose to retard or cease the movement of a machine. Within the strategy of performing this operate, the brake absorbs both the kinetic vitality of the transferring member or potential vitality given up by objects being lowered by hoists, elevators, and so forth. Within the earlier articles, we mentioned how we will calculate the vitality absorbed by a brake and Warmth Dissipation throughout Braking. Allow us to see the several types of Brakes.
As we talked about above that the brake is used to retard or cease the movement of a machine. This motion is named Braking. Within the strategy of braking, the brake absorbs both the kinetic vitality of the transferring member or potential vitality given up by objects being lowered by hoists, elevators and so forth. The vitality absorbed by brakes is dissipated within the type of warmth. This warmth is dissipated within the surrounding air (or water which is circulated by way of the passages within the brake drum) in order that extreme heating of the brake lining doesn’t happen.
The design or capability of a brake relies upon upon the next components:
- The unit strain between the braking surfaces
- The coefficient of friction between the braking surfaces
- The peripheral velocity of the brake drum
- The projected space of the friction surfaces
- The flexibility of the brake to dissipate warmth is equal to the vitality being absorbed.
The foremost practical distinction between a clutch and a brake is {that a} clutch is used to maintain the driving and pushed member transferring collectively, whereas brakes are used to cease a transferring member or to regulate its pace.
We additionally solved an instance downside to cease A car of mass 1200 kg is transferring down the hill at a slope of 1:5. by discovering how a lot quantity of Braking Torque is required to cease the car within the earlier article.
Varieties of Brakes
The brakes, in response to the means used for remodeling the vitality by the braking component, are labeled as:
- Hydraulic brakes e.g. pumps or hydrodynamic brakes and fluid agitators,
- Electrical brakes e.g. turbines and eddy present brakes
- Mechanical brakes
The hydraulic and electrical brakes can’t carry the member to relaxation and are largely used the place massive quantities of vitality are to be reworked whereas the brake is retarding the load corresponding to in laboratory dynamometers, freeway vehicles, and electrical locomotives. These brakes are additionally used for retarding or controlling the pace of a car for downhill journey.
The mechanical brakes, in response to the course of performing power, could also be divided into the next two teams:
- (a) Radial brakes. In these brakes, the power performing on the brake drum is within the radial course. The radial brakes could also be subdivided into exterior brakes and inner brakes. In keeping with the form of the friction component, these brakes could also be block or shoe brakes and band brakes.
- (b) Axial brakes. In these brakes, the power performing on the brake drum is within the axial course. The axial brakes could also be disc brakes and cone brakes. The evaluation of those brakes is much like clutches.
Since we’re involved with solely mechanical brakes, due to this fact, these are mentioned intimately, within the following pages.
Single Block or Shoe Brake
A single block or shoe brake is proven within the following determine. It consists of a block or shoe that’s pressed in opposition to the rim of a revolving brake wheel drum. The block is fabricated from a softer materials than the rim of the wheel. This sort of brake is often used on railway trains and tram automobiles.
The friction between the block and the wheel causes a tangential braking power to behave on the wheel, which retard the rotation of the wheel. The block is pressed in opposition to the wheel by a power utilized to at least one finish of a lever to which the block is rigidly fastened as proven within the following determine. The opposite finish of the lever is pivoted on a set fulcrum O.
(Line of motion of tangential power passes by way of the fulcrum of the lever.)
Pivoted Block Brake or Pivoted Shoe Brake
We’ve got mentioned within the earlier article that when the angle of contact is lower than 60°, then it could be assumed that the conventional strain between the block and the wheel is uniform. However when the angle of contact is larger than 60°, then the unit strain regular to the floor of contact is much less on the ends than on the heart. In such circumstances, the block or shoe is pivoted to the lever as proven within the following determine, as a substitute of being rigidly connected to the lever.
Double Block Brake or Double Shoe Brake
When a single block brake is utilized to a rolling wheel, a further load is thrown on the shaft bearings as a result of regular power (RN). This produces bending of the shaft. To beat this downside, a double block or shoe brake as proven within the following determine is used.
It consists of two brake blocks utilized on the reverse ends of a diameter of the wheel which eradicate or cut back the unbalanced power on the shaft.
The brake is ready by a spring which pulls the higher ends of the brake arms collectively. When a power P is utilized to the bell crank lever, the spring is compressed and the brake is launched.
This sort of brake is usually used on electrical cranes and the power P is produced by an electromagnet or solenoid. When the present is switched off, there is no such thing as a power on the bell crank lever, and the brake is engaged routinely as a result of spring power thus there shall be no downward motion of the load.
Easy Band Brake
A band brake consists of a versatile band of leather-based, a number of ropes, or metal lined with friction materials, which embraces part of the circumference of the drum. A band brake, as proven within the following determine, is named a easy band brake during which one finish of the band is connected to a set pin or fulcrum of the lever whereas the opposite finish is connected to the lever at a distance b from the fulcrum.
When a power P is utilized to the lever at C, the lever turns in regards to the fulcrum pin O and tightens the band on the drum and therefore the brakes are utilized. The friction between the band and the drum offers the braking power. The power P on the lever at C could also be decided as mentioned beneath:
(a) Clockwise Rotation of Drum (b) Anticlockwise Rotation of Drum
Differential Band Brake
A band brake consists of a versatile band of leather-based, a number of ropes, or metal lined with friction materials, which embraces part of the circumference of the drum. A easy band brake during which one finish of the band is connected to a set pin or fulcrum of the lever whereas the opposite finish is connected to the lever at a distance b from the fulcrum. In a differential band brake, as proven within the following determine, the ends of the band are joined at A and B to a lever AOC pivoted on a set pin or fulcrum O. It might be famous that for the band to tighten, the size OA have to be larger than the size OB.
(a) Clockwise Rotation of Drum (b) Anticlockwise Rotation of Drum
Band and Block Brake
The band brake could also be lined with blocks of wooden or different materials, as proven within the following determine. The friction between the blocks and the drum offers braking motion. Let there be an ‘n’ variety of blocks, every subtending an angle 2 θ on the heart and the drum rotates in an anticlockwise course.
Inside Increasing Brake
An inner increasing brake consists of two footwear S1 and S2 as proven within the following determine. The outer floor of the footwear is lined with some friction materials (normally with Ferodo) to extend the coefficient of friction and to stop the sporting away of the steel. Every shoe is pivoted at one finish a couple of fastened fulcrum O1 and O2 and made to contact a cam on the different finish.
When the cam rotates, the footwear are pushed outwards in opposition to the rim of the drum. The friction between the footwear and the drum produces the braking torque and therefore reduces the pace of the drum. The footwear are usually held in an off place by a spring as proven within the above determine. The drum encloses the whole mechanism to maintain out mud and moisture. This sort of brake is often utilized in motor automobiles and lightweight vehicles.
That is all in regards to the several types of Totally different Varieties of Brakes. To learn extra about these brakes, comply with the person article hyperlinks to get to know extra. Tell us what you concentrate on this text within the remark part beneath.
