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Crash test

In this video you can see every thing about crash test…

Crash test is the destructive type of test of a vehicle which is conducted to check the destructive abilities of a vehicle and then rate the vehicle according to that…

There are dummies sitting inside the cars at the time of accidents.. These dummies mimic the real-time situation of a human sitting inside a vehicle. These dummies have different sensors on different parts of the body to sense/detect the amount of forces coming in different parts of dummy…

There 5 types of crash test that a vehicle need to pass…

1. Frontal impact test

   In this imapct test the car is collided with the crushable aluminum box (that simulates as another car coming from front) at a speed of 64kmph and then the different forces on the dummy is calculated… And hence the rating to that vehicle is provided

2. Side impact test

In this the aluminum crushable box hits the car from side ways at a speed of 50kmph

3. Pedestrain test

This is done to check the amount of forces that may come on the pedestrian ID a car hits the pedestrian at 40kmph…

The forces analysed in different parts as head, knee,elbow, leg, thigh &head of a child. And the forces must be minimum as most of the forces should be absorbed by the body of the vehicle….

4. Pole test

Car is simulated to hit the pole from side ways At a speed of 30kmph… And then it is determined that how much forces are coming in that side of the dummy…

5.Whiplash test

In this test the forces are analysed on the dummy by simulating the crash from the rear if a car from the rear hits a stationary car at a speed of 35kmph.. There will be huge amount of focres going to act on the neck and head of the  dummy.. And these forces are analysed in this test.

Thanks for reading.

Please reply if you like it or not. 🙂

BRAKE BIASING

At the time of braking the weight of the vehicle transfers to the front wheels due to which more braking effort is required on the front wheels,therefore brake biasing is required.If brake biasing is not done then rear tires may skidd and braking won’t be efficient.
for BIASING the BRAKES , a biasing bar is required which is connected to master cylinders.
there are 2 methods of achieving brake biasing:
1> by tilting the bisaing bar
2> by shifting the point of application of force

please watch the video i have explained everything in detail 🙂

OHV v/s DOHC v/s SOHC

 

OHV – OverHead Valve

an engine design where the camshaft is installed inside the engine block and valves are operated through lifters, pushrods and rocker arms

 Advantages of an OHV: lower cost, compact size and proven durability.

SOHC -Single OverHead Cam

In a SOHC engine the camshaft is installed in the cylinder head and valves are operated either by the rocker arms or directly through the lifters.

Advantages of sSOHC–  precise timing at higher RPMs, possible to install three or four valves per cylinder.

DOHC-Double OverHead Cam

DOHC engine has two camshafts and 4 valves per cylinder. One camshaft operates intake valves  while another camshaft controls exhaust valves.

Advantages oh DOHC-DOHC engine can “breathe” better and thus produces more horsepower out of smaller engine volume.

 

 

 

Weight transfer

There are three ways that weight transfers can occur:

  • Acceleration
  • Deceleration
  • Steering

Weight transfers occur as a result of the chassis twisting around the car’s roll centre, which determined by the natural suspension setup. When accelerating, braking or steering, the body of the car rotates in the opposite direction, which compresses the suspension on one side of the car, while releasing the weight on the other side.
Hey friends this is a video explaining about how weight transfer takes place in vehicles at the time of turning braking and acceleration…
A very helpful video

ackermann steering geometry

The Ackerman Steering Principle defines the geometry that is applied to all vehicles (two or four wheel drive) to enable the correct turning angle of the steering wheels to be generated when negotiating a corner or a curve.

Ackermann steering geometry is a geometric arrangement of linkages in the steering of a car or other vehicle designed to solve the problem of wheels on the inside and outside of a turn needing to trace out circles of different radii.

The typical steering system, in a road or race car, has tie-rod linkages and steering arms that form an approximate parallelogram, which skews to one side as the wheels turn. If the steering arms are parallel, then both wheels are steered to the same angle. If the steering arms are angled, as shown in Figure 1, this is known as Ackerman geometry. The inside wheel is steered to a greater angle then the outside wheel, allowing the inside wheel to steer a tighter radius.

you can understand it much better on my youtube channel “BHOLA MECHTECH”.

ackerman steering in english: https://www.youtube.com/watch?v=axppRLteY1Y&t=5s

ackerman steering in hindi: https://www.youtube.com/watch?v=_FiiASe3SQo&t=13s

thanks for reading…

please leave comments

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SOLEX CARBURETOR

 

Solex carburetors are famous for it ease of starting even in cold, for its performance and for its reliablity. It consist of various fuel circuits such as starting, idling operation, normal running, acceleration.

 Solex Carburetor Starting Circuit :The throttle valve remains in closed position during starting. The petrol is supplied to the starter petrol jet through first passage from the float chamber and the air through the starter air jet for starting operation.
Starting Valve which have different sizes hole, is made from flat disc. The position of various holes can be adjusted in front of starter petrol jet by starter lever and then air is mixed coming from starter air jet .This air-fuel mixture, passes through another holes of starter valve, in a passage of the carburetor, below the throttle valve. The suction stroke of the engine sucks this mixture into the cylinder. This mixture is rich enough to start the engine. After the engine starts and speed increases, a weak mixture is required; therefore, a small hole of the starter valve is brought in front of the starter petrol jet by means of starter lever, there by reducing the quantity of petrol, which weakens the air-fuel mixture. Similarly next smaller hole of the starter valve is brought in front of starter petrol jet till the engine attains its normal speed then the starter valve is closed by bringing the starter lever to its off position.

At normal running speed, starting circuit is closed and throttle valve is opened. The normal running circuit consists of main jet which receives the petrol through second passage, from the float chamber as the throttle valve is opened sufficiently; the air is drawn through the venturi where the petrol mixes up with it forming a suitable mixture for the normal running of the engine. In this case, only throttle valve, governed the air-fuel ratio.

Solex Carburetor Accelerating Circuit .The engine requires an extra rich mixture, during acceleration period. To obtain extra rich mixture, the fuel is pumped under pressure into the main air passage or in the venturi through an injector. Diaphragm pump is used to create pressure, which is actuated by a lever connected to the accelerator. The pump sucks the petrol from the float chamber through the pump valve and forces it through third passage into the main passage through an injector above the venturi of the carburetor.

Solex Carburetor Idling and Slow Running Circuit: During the idling operation, the throttle valve is kept closed and the engine receives the mixture through a port opening below the throttle valve, whose area can be varied by an idle adjusting screw according to the need of the engine. The petrol is supplied to a pilot petrol jet from the main jet fuel circuit through fourth passage and the air from a pilot air jet .The petrol and air thus supplied mix up in the idle passage and go to a port situated below the throttle valve from where the mixture is sucked by engine.

beetle_solex_30pict-3_carburettor_1

for better understanding of the topic you can watch my youtube video. for that video you can check out my channel “BHOLA MechTech”.

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