How clever are you with mechanical stuff etc
25 October 2007, 01:44 PM
#1
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25 October 2007, 02:07 PM
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I got 92% too (and a couple of the ones I got wrong were ambiguous IMHO!) - you can click 'review' to go through your answers at the end.
The sun gear rotates clockwise, and the planet gears move clockwise, while each one individually rotates anticlockwise.
The sun gear rotates clockwise, and the planet gears move clockwise, while each one individually rotates anticlockwise.
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25 October 2007, 02:46 PM
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90% (450 points) 
I hate worm gears (would help if I could zoom the picture)
Planetry gears are a doddle once you've rebuilt an automatic gearbox
I hate worm gears (would help if I could zoom the picture)
Planetry gears are a doddle once you've rebuilt an automatic gearbox
Last edited by Tart Man; 25 October 2007 at 02:49 PM.
25 October 2007, 03:26 PM
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25 October 2007, 03:39 PM
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25 October 2007, 03:41 PM
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Yeah it does - It says the ring gear is stationary, the sun gear is rotating clockwise and it asks what happens to the planets.
Well the way it answers the question it asks whether the air goes into the chamber as result of the piston "sucking" the air in - Which of course s wrong, because its not the piston doing the sucking.
which one?
which one?
25 October 2007, 04:13 PM
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250kg on each side - one is looped straight over the pulley, the other one is looped round a second bottom pulley and back to the top. It says it will be unstable. Some dark an smelly corner of my mind tells me otherwise.
25 October 2007, 04:44 PM
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I Agree i got 88% and failled on the induction question and the pulley that is tied off on one end with a hook, how is that ?
It is a test for Ford engineers though which says a lot.
It is a test for Ford engineers though which says a lot.
25 October 2007, 04:49 PM
#19
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I * think* the piston "sucking" is an effect, not a cause. In other words - after the "bang" the piston is forced downwards. The air pressure in the chamber at that point is less than the "outside word" therefore the "outside world" rushes to fill the chamber.
Why is the pressure lower? because the explosion has just created a vacuum - Rather than the piston explicity "sucking" air in
If you see what I mean.
Yeah I must admit, some of the load and pulley stuff is where I lost my marks. I *think* its because you have other pulleys taking some of the load. I actually got that one right, but It was more an educated guess than "i know thats right". I know what you mean, when you look at the diagram, the whole lot is suspended in air effectively , thereofre you wouldn't expect it to make a jot of difference.
Why is the pressure lower? because the explosion has just created a vacuum - Rather than the piston explicity "sucking" air in
If you see what I mean.
Yeah I must admit, some of the load and pulley stuff is where I lost my marks. I *think* its because you have other pulleys taking some of the load. I actually got that one right, but It was more an educated guess than "i know thats right". I know what you mean, when you look at the diagram, the whole lot is suspended in air effectively , thereofre you wouldn't expect it to make a jot of difference.
25 October 2007, 05:00 PM
#20
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After the 'bang' there's an exhaust stroke... the explosion doesn't create a vacuum, it creates a massive increase in pressure, which then does work pushing the piston down. Then the exhaust valve opens and the exhaust gas is pushed out as the piston rises again.
I think it's just arguing about semantics TBH. If the question were about a turbocharged engine, nobody would suggest for a moment that the answer was anything other then 'the air gets blown in'. Now imagine slowly turning down the boost pressure; at what point does the answer to the question change? A: It doesn't.
I think it's just arguing about semantics TBH. If the question were about a turbocharged engine, nobody would suggest for a moment that the answer was anything other then 'the air gets blown in'. Now imagine slowly turning down the boost pressure; at what point does the answer to the question change? A: It doesn't.
25 October 2007, 05:12 PM
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But it doesn't suck air in on the first downstroke
Bang - Piston goes down caused by explosion
exhaust valve opens and piston moves up (driven by explosion from other cylinder)
exhaust valve closes and piston goes down (driven by explosion from other cylinder) - This is the point where air enters. The piston is going down causing the pressure to drop. Saying that this isn't actually sucking is merely semantics. I would be surprised if someone who was hpoing to become a trainee Ford engineer would be that interested in Brownian motion and atmospheric diffusion
Bang - Piston goes down caused by explosion
exhaust valve opens and piston moves up (driven by explosion from other cylinder)
exhaust valve closes and piston goes down (driven by explosion from other cylinder) - This is the point where air enters. The piston is going down causing the pressure to drop. Saying that this isn't actually sucking is merely semantics. I would be surprised if someone who was hpoing to become a trainee Ford engineer would be that interested in Brownian motion and atmospheric diffusion
Last edited by fast bloke; 25 October 2007 at 05:14 PM. Reason: p.s. Andy's answer wasn't there when I started typing this
25 October 2007, 06:08 PM
#25
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It sucks IMO (question 48) 
Although bear in mind this is Diesel test and most diesel are Turbo, and all run with nearly zero manifold vacuum or positive pressure for nearly all the time (i.e equivelent to a petrol engine at full throttle).
Still I belive sucks is the better answer for most applications. For instance; when the turbo is barely spinning.
Although bear in mind this is Diesel test and most diesel are Turbo, and all run with nearly zero manifold vacuum or positive pressure for nearly all the time (i.e equivelent to a petrol engine at full throttle).
Still I belive sucks is the better answer for most applications. For instance; when the turbo is barely spinning.
25 October 2007, 06:10 PM
#26
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But it doesn't suck air in on the first downstroke
Bang - Piston goes down caused by explosion
exhaust valve opens and piston moves up (driven by explosion from other cylinder)
exhaust valve closes and piston goes down (driven by explosion from other cylinder) - This is the point where air enters. The piston is going down causing the pressure to drop. Saying that this isn't actually sucking is merely semantics. I would be surprised if someone who was hpoing to become a trainee Ford engineer would be that interested in Brownian motion and atmospheric diffusion
Bang - Piston goes down caused by explosion
exhaust valve opens and piston moves up (driven by explosion from other cylinder)
exhaust valve closes and piston goes down (driven by explosion from other cylinder) - This is the point where air enters. The piston is going down causing the pressure to drop. Saying that this isn't actually sucking is merely semantics. I would be surprised if someone who was hpoing to become a trainee Ford engineer would be that interested in Brownian motion and atmospheric diffusion
25 October 2007, 06:11 PM
#27
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78 % 
44 and 48 are highly dubious imo
If id bother to enlarge the worm gear pic id have passed
44 and 48 are highly dubious imo
If id bother to enlarge the worm gear pic id have passed
Last edited by dpb; 25 October 2007 at 06:14 PM.
25 October 2007, 06:17 PM
#28
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I had posted it the first time with cylinders 1,2,3 and 4, then edited it cos I knew some smarta5e (that'd be you then 
)would mention twins, V8's etc etc. I spent 10 minutes doing the whole cycle for any engine, which was then waaayyyyy too complicated, so I went for this one, which is why Andy managed to give the same answer 15 minutes quicker
)would mention twins, V8's etc etc. I spent 10 minutes doing the whole cycle for any engine, which was then waaayyyyy too complicated, so I went for this one, which is why Andy managed to give the same answer 15 minutes quicker
25 October 2007, 06:41 PM
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88% - I wasn't sure of the pulley effect on force. I agree with the piston one, mind - saying it is pulled in by suction is woolly scientific thinking/language. The action of the piston produces a negative pressure inside the cylinder, which the atmosphere (being under pressure) rushes in to equalise.
