Report from Paul
The automotive mechanics class for 3rd – 4th graders met on Thursday and started learning about the automotive engine, viewing a model engine.
This week the 3rd – 5th graders learned about the tools a mechanic might use, including different kinds and sizes of screwdrivers, nut-drivers, and all kinds of wrenches, pliers, and wire cutters. The socket set and the giant box wrench were big hits. The 3rd – 4th graders also looked at fasteners, learning the difference between a bolt and a screw and how bolts are sized. Please take time to let your student look through your toolbox and see if they can correctly name the items in there. Next week the 5th graders will discuss fasteners and the 3rd – 4th-graders will move on to understanding different types and arrangements of internal combustion engines and discuss the four phases of a four-stroke engine.
This week the 5th-graders finished up fasteners and we had a nice discussion on how a ratchet works. The 3rd-and 4th-graders moved on to identifying engines by displacement and arrangement and we went over the four strokes of a four-stroke engine. It’s a complicated bit so we may need to go over that again. Please take some time to go have a look at the family vehicle engine and see if you can determine the size (displacement) and arrangement of cylinders. Next week the 5th-graders will identify engines and the 3rd– and 4th-graders will discuss fuel delivery systems.
This week all students worked on understanding the four cycles of a 4-stroke engine and how the engine converts chemical energy to the circular motion required to power the wheels. Next week I will be out due to other obligations, but the Mitchells have kindly agreed to take over for me and will discuss the fundamentals of an electric motor.
The automotive mechanics class was taught by Bridget Mitchell, who explained some of the electrical aspects of an engine, including how electricity is generated by an engine.
This week we discussed fuel and fuel delivery. We talked about how gasoline gets from the gas tank to the pistons via a mechanical or electric fuel pump and mixes with air via a carburetor or fuel injection. We also discussed the differences between diesel, ethanol, and gasoline and what an octane rating means. Then we walked outside to look over a ‘78 Lincoln Mark V.
Next time you stop to fuel up the family car with your student, show them the different buttons on the pump and see if they know what they mean.
Next week we will look at ignition and spark plugs and how the car controls combustion.
This week we looked at how an engine controls ignition via a distributor and spark plugs. It was a little challenging without an actual distributor to show them but I think they got the idea. We looked at a cap and rotor from an old Mercedes and an old Dodge and discussed how different the engineering approach is. Then we walked outside to look over a 1983 Porsche 944. Next week we will have a light lesson on transferring the rotation of the crankshaft to the wheels and possibly brakes if we get that far.
This week we discussed the drivetrain. By now we know how the engine converts liquid energy from gasoline to mechanical energy, but how does that energy get to the ground to push the car forward? We talked about how the gears in the transmission allows the car to build speed and how universal joints allow up and down motion while carrying circular torque to the driveshaft and how the differential changes the direction of the rotation to the axle. We also discussed the difference between 2-wheel drive, 4-wheel drive, all-wheel drive, and front and rear wheel drive. Then we went outside for a look at a 1989 Mercedes 560SEL.
Next week we will discuss the mechanics of the cooling system along with how the heater works.
This week we discussed how an engine controls temperature with a cooling system. We learned what coolant is made of, how coolant circulates, and how the radiator disperses heat. We also discussed how the heater works to keep us warm in a similar way and looked at a heater core and a drum fan. We didn’t get to look over any old cars this week because it was so windy on Tuesday. Next week we will discuss air conditioners and how refrigeration transfers energy to keep us cool.