The German mining machine, Bagger 288 is a bucket-wheel excavator built by the Krupp company for the energy and mining firm Rheinbraun. The Bagger stands higher than the Statue of Liberty and even heavier than the Eiffel Tower, with a weight of 13,500 tons.

The mobile strip mining machine was completed in 1978 superseding the Big Muskie as the heaviest machine in the world. The design and manufacturing of the machine took five years, with an additional five years for the assembly. The total cost of the machine neared $100 million. The bagger uses a revolving wheel of buckets to shovel out the dirt in open-pit mines. It can dig out 8.5 million cubic feet of land per day, and when it reaches the depth, it can extract 265,000 tons of fuel every day. The monster only requires three to four people for its operation.

The buckets on the revolving wheel deliver the soil or fuel to 4 conveyor belts, each having a width of 10.5 feet. The belts carry the material at a speed of over 11 mph. The 13,000 tons of Bagger’s weight is carried by 8,600 square feet of tread moving it with a steady speed of 0.4 miles an hour. Electric cables as thick as a man’s arm, spanning over 5,600 feet deliver electric power to the excavator. The power this behemoth uses can power a city of 20,000 people. 88,000 pounds of paint cover the entire structureThe two pylons of the structure stand at the height of 148 feet held by 7,218 feet of steel suspension cables.
The bucket wheel alone stands as high as a seven-story building at 71 feet. Each of the 18 buckets around the wheel weighs 7,700 pounds when empty. One bucket can dig out 230 cubic feet of soil alone which can easily fill a cargo van.


Thermit welding is a fusion welding process that makes use of the intense heat produced when a mixture containing iron oxide and powdered aluminium is ignited. The reaction is based on the high affinity of aluminium is ignited.It reduces iron oxide to thermit steel and slag, like this
8Al + 3Fe3O4 – -> 9Fe + 4Al2O3 (Slag) + Heat
The superheated molten metal is poured at the desired place which on solidification forms the welded joint. The process is thus essentially a combination of casting and welding processes. The Thermit mixture consists primarily of finely divided aluminium and iron oxide in the ratio of about 1: 3 by weight. Other metal oxides that can be used in place of iron oxide include oxides of Copper, Nickel, Chromium or Manganese but Iron oxide Thermit is the most commonly used. The mixture is filled in a specially designed refractory crucible and the reaction is started by igniting the mixture with a highly inflammable powder consisting of Barium Peroxide.
When the mixture is ignited, an ignition temperature of 1150 deg Celsius is attained which initiates the main thermit reaction. The reaction is self sustaining and very rapid as it is exothermic. A temperature of the order of 3000 deg Celsius is produced resulting in super heated thermit steel. Slag being very light floats over the thermit steel thereby protecting the metal from atmospheric gases. Apart from the basic ingredients of the thermit mixture other materials may be added to produce a desired thermit melt for any specific application.
Working Operation:
In making a thermit weld a mould is built around the sections to be welded and is preheated before use. This is done by first cutting the ends of the pieces to be welded to provide a gap with parallel faces. The gap is filled with wax which serves as a pattern for the weld. The ends of the work pieces are enclosed in a suitable flask and moulding sand rammed around the joint taking care to provide openings for the runner, riser and a heating gate.
Heat is applied through the melting gate to melt out the wax and to preheat the ends of the pieces to be welded. The heating gate is then plugged with an iron plug or sand core to prevent flow of thermit metal. Thermit reaction is started in the thermit crucible and the resulting superheated steel is let in, from the bottom of the crucible. The slag being lighter floats over the molten metal in the crucible. It flows last and remains at the top of the mould where it solidifies. Clean metal enters the mould around the sections to be welded.
The temperature of the molten steel entering the mould is around 2500 degree Celsius. The heat of the superheated metal fuses and amalgamates the sections together forming joint on solidification. After the joint has solidified the mould is broken open and discarded.
The thermit welding process is useful for welding heavy sections. Though initially used primarily for joining of rails the process can be used for repair work of heavy parts like tracks, spokes of large wheels, broken motor casings, and connecting rods.

1. The heat necessary for welding is obtained from a chemical reaction and thus no costly power – supply is required. Therefore broken parts (rails etc.) can be welded on the site itself.
1. Thermit welding is applicable only to ferrous metal parts of heavy sections, i.e., mill housing and heavy rails sections.
2. The process is uneconomical If used to weld cheap metals or light parts.


They are called crawlers or chain(in simple words). Made from steel or rubber (in case of small machine or vehicle). Actually it is used in heavy duty machine ( Crane). This crawlers is required for better traction while moving (as it is heavyweight) and larger base area (contact pitch) while working. It take place of big wheels (tyre).
Generally it is hydraulic drive but In case of small crawlers like snow mobiles it is mechanically driven.
This type of crowlers are used in verities of Automobile, From small snow mobiles to large crains. This type of vehicle are called SPV ( special purpose vehicle)
Incase of snow mobiles main purpose of crowlers is weight distribution on snow same is in the case of tank (for better off-roading).


As the car brakes, the center of gravity causes a torque (like a big wrench turning the car toward its nose) to force the car to its front tires.
The center of gravity of the car wants to keep going forward. The only thing slowing it down is the transfer of force between the road, and the contact patch of the tire on the road.
That force, which the tire makes with the road, is very simplistic...  That force is composed of only two things. The weight pushing down on the tire, and some number that makes up for the stickiness of the tire, and the terrain it is on.  A sticky tire on good pavement, a high number; a normal tire on ice, a low number. 
Since that force on the tire is highly dependant on the weight on that tire, the amount of braking that the tire can do is directly related to the weight imparted on the tire.

As you can see from the above picture, the front tires can see a bit more weight than the rear under hard braking.
the highest braking capabilities are much higher on the front than on the rear, therefore, we must ensure that those brakes are up to the task.
How do we do that?
Well, it all comes back to torque. Torque is just some force that acts over some distance. It is for this reason that you might use a longer bar on a wrench that you are trying to get a stuck bolt out with.
Let's say you are trying to stop a big heavy tractor tire from spinning. Imagine that you put a little brake pad from the front of a bike a few millimeters from the center of the wheel.  It wouldn't do much would it? Then imagine that you put that same brake, with the same pressure, as far from the center as you could.  Imagine that you could actually put it a few meters farther than the tire. In fact, let's go all the way and say that you could put that little brake pad a few skyscrapers away.  That same little brake pad could do a LOT more to stop that tire.  It would be no problem.
This same principle helps us exert the extra force that we now know front wheels can receive. So bigger diameter brakes up front help even-out the pressure required to stop the car. Those higher forces require additional thickness  to transfer those forces through the disk, and into the hub.


The Honda Combi Brake system was introduced in India with the Honda Activa in 2009. However, this system has been in use since more than 30 years internationally. The Honda Combi Brake system is a first-in-industry technology.

What is the Honda Combi Brake System?

The most efficient way of braking is to apply the front and rear brakes simultaneously. But it is a practice, most two-wheeler riders have not mastered.Combi brake means that the brake will act on front and rear wheel together every time you apply the brakes. This means a lot of improved safety.

How does the Honda Combi Brake System Enhance Safety?

In two wheelers (scooters and bikes), there are two separate brake controls for front and rear wheels.Most of two-wheeler riders apply only rear wheel brake, or use only rear brake in most of the cases. However for most effective braking and stopping in small distance safely without loosing control, both front and rear brakes should be used together. Most people fear using front brakes too much because if you press them too hard, the scooter/bike may skid and the rider will fall badly.

Honda Combi Brake system applies the front-brakes in the correct amount whenever rear brakes are applied. This applies both brakes when you apply only rear one. This means that the scooter rider need not worry about using front brakes, they will be used in correct amount automatically when the rear brakes are used. See the image above, the highlighted green area shows how they have put an extra-cable to brake lever control of Honda-Activa 2009 to make combi-brakes work.
Advantages :-
Honda Combi Brake with Equaliser, ensures distribution of Force between the Front and Rear Wheel at the same time, giving perfect balance to the rider.
It ensures that rider with low expertise is also confident while braking.
Simultaneous application of Front and Rear Brake leads to the most effective braking.


What is the difference between 20bhp @ 4000 RPM vs 20bhp @ 8000 RPM?

BHP is brake horse power i.e. the power generated at the crankshaft of the engine. Now in these both cases there is 20bhp. So we are assuming that these are two different engines with different configurations.

So in first case, engine generates 20bhp net power while running at 4000 RPM. On the other hand, in second case, engine generates 20bhp net power while running at 8000 RPM.

In engines, we study a power-torque curve to check performance of engine. Now from this P-T curve, you will find that power of any engine increases with increasing in RPM for some range of RPM. There comes a point of RPM where this power produced by an engines gets maximum and after this point the power generation decreases with increase in RPM.

So in these cases the power that has mentioned is the pick power an engine can produce during that particular RPM. When we look at any car's or vehicle's brochure, you will find this explanation in power category. But remember the power that the company has mentioned is max power, which you will hardly get at those high RPM. Vehicles don't run at those high RPM constantly.

Now in these cases, for engine 1 the value of RPM is low(4000 RPM) and still generating 20bhp, so that means you will get more value of torque compared to engine 2 which has 8000 RPM. As we all know torque is inversely proportional to RPM, more RPM than less torque and vice versa.


In Shaper machine, tool is having reciprocating motion and w/p is clamped on table which is stationary. It is mostly suitable for light duty operation.In Shaping large cutting force is transferred to tool.
In Planer machine, tool is having stationary and w/p is clamped on table which is reciprocating motion. It is mostly suitable for Heavy duty operation.In planner large cutting force is transferred to table