La pelle mécanique sur chenilles for kids

< MD - Let’s Build An Excavator

- Children, today, we are going to put together a tracked excavator from the construction set!
- Hooray! An excavator!
- Let’s begin with something that helps the excavator to travel.
- This is the track frame. It has sprockets and rollers.
- An excavator’s sprockets look like stars.
- These are tracks. Now we are going to put both of the tracks on the sprockets. Tracks let the excavator go around uneven ground, like rough debris that you find on building sites.
- Wow!
- This is the rotating platform. Let’s set it on the track frame. On the rotating platform you will find the driver’s cab, this is where the driver controls the excavator, engine, pumps and counterweight. The platform joins with the track frame with the help of this slewing device.
Do you know why we need a counterweight? It is needed so the excavator doesn’t fall forward when its bucket is loaded. This is the boom. We join it to the rotating platform near the driver's cab. Now we'll add an arm. Is anything missing from our excavator?
- The bucket!
- Of course! Without it the excavator won’t be able to do its main job – digging. Join the arm and the bucket together.
- Excavator is ready!
- Well, how is our excavator?
- It is great!
- Have a look at how the excavator’s equipment works.
- The excavator has hydraulic fluid. With the help of the pumps, oil is fed with high pressure into the hydraulic fluid. It puts pressure on the pistons and the pistons push out. When there is negative pressure the pistons hide back inside.
These cylinders of hydraulic fluid are responsible for the movement of the boom.This cylinder of hydraulic fluid makes the arm maneuver.
- This device, the one joining bucket with the piston is called H-link or Bucket Linkage. Its mechanism lets the bucket to vastly flex and extend. The excavator’s platform spins on its axes all the way around.
- To the place of work, the excavator is delivered on special trucks or by railway.
- Excavators – are unreplaceable workers on the building site. They dig trenches for the laying of the pipes and underground utilities. Also, they are used for digging up foundation pits for future buildings.
- It is quite loud in the driver's cab.
- How does the excavator turn? It doesn’t have normal wheels.
- To turn the excavator, the driver stops one of the tracks and the other one goes round the stopped one.
- How does the excavator get on the wagon?
- Here, you can see what tricks the excavator gets up to.
- Oh, how it pushes away with the bucket! How does it do that!
- Wow!
- Bye-bye excavator!