How good is YOUR mechanical knowledge?

**steveb64** · 23rd October 2007, 23:29

Check this out...

http://www.forddoctorsdts.com/quizze...alAptitude.php

BTW - I got 430 points - 86%. On first try. And I'm NOT a mechanic. Pass is 80%.

So - how good are you?

**Ocean1** · 24th October 2007, 00:12

Originally Posted by steveb64

So - how good are you?

Very very good aparently, for a Ford diesel mechanic.

Fortunately I'm not.

**howdamnhard** · 24th October 2007, 00:18

I got 88%,must be getting rusty.

**sAsLEX** · 24th October 2007, 04:12

Question 48 the answer is wrong!

NA engines. Air is sucked into the engine by the vacuum created as the piston descends I am sure of it. If I covered the intake of the lawn mower with my hand it would suck my palm until it starved, no kill switch you see.

90% for an elect engineer who got one of the battery questions wrong by not payinng enough attention!

**bungbung** · 24th October 2007, 08:23

96%, need to pay more attention

**Fooman** · 24th October 2007, 08:38

Originally Posted by sAsLEX

Question 48 the answer is wrong!

NA engines. Air is sucked into the engine by the vacuum created as the piston descends I am sure of it. If I covered the intake of the lawn mower with my hand it would suck my palm until it starved, no kill switch you see.

90% for an elect engineer who got one of the battery questions wrong by not payinng enough attention!

No such thing as sucking - there is a pressure differential between the lower pressure cylinder and the higher pressure atmosphere. The fluid moves from a volume of high pressure to low pressure to minimize the energy state of the system. The atmospheric pressure forces your hand over the lawn mower intake - the "suck" you feel is the effect of the higher pressure inside your skin compared to the pressure in the intake.

Think of water in a dam - does it get sucked down the penstocks, or does it get pushed down by the higher pressure/head due to the height of the water.

Cheers,
FM

**steveb64** · 24th October 2007, 08:41

Originally Posted by sAsLEX

Question 48 the answer is wrong!

NA engines. Air is sucked into the engine by the vacuum created as the piston descends I am sure of it. If I covered the intake of the lawn mower with my hand it would suck my palm until it starved, no kill switch you see.

90% for an elect engineer who got one of the battery questions wrong by not payinng enough attention!

My thoughts entirely. The ONLY reason atmospheric pressure can push ANY air into the engine, is due to the pressure differential caused by the piston descending...

Hmmm - at least I got all the electrical questions right... Did mess up a couple of others by not paying enough attention...

**Steam** · 24th October 2007, 08:47

Originally Posted by Fooman

No such thing as sucking

Yes there is. It is a subjective term which depends on which side of the pressure differential you are standing. If the air is going into the hole that's sucking. If the air is coming out of the hole that's pushing.

**Winter** · 24th October 2007, 09:06

76%. :-(

I'm going to take it again in a couple of days to see if I absorbed any of it.

**sAsLEX** · 24th October 2007, 09:11

Originally Posted by Fooman

No such thing as sucking -

Originally Posted by http://auto.howstuffworks.com/question685.htm

When the piston moves from top to bottom, it sucks in a certain amount of air. How much air it can suck in depends on how big around the piston is, and how far it moves when it goes from top to bottom.

You find a reference to back up your story!

Originally Posted by http://www.carbibles.com/fuel_engine_bible.html

Suck, squeeze, bang, blow
Not a sexual maneuver, but rather the common description for how an internal combustion engine works. The basic way all internal combustion engines work is to suck in a mixture of fuel and air, compress it, ignite it either with a spark plug or by self-igntion (in the case of a diesel engine), allow the explosion of combusting gasses to force the piston back down and then expel the exhaust gas.

**steveb64** · 24th October 2007, 09:13

...and there's a pulley question where they reckon there's NO difference between a straight lift (no pully - lifting directly upwards) and using a single pulley - pulling at either 90 degrees from pulley-load or 180 degrees...

Short of trying to find a pulley in the mass of accumulated crap that's my garage, and using a spring scale to measure... naaahhhh too much work... I thought that even using a single pulley would reduce the work load?

**hazard02** · 24th October 2007, 09:28

88%- Not bad for half a degree in robotic engineering. I'd be set if I was studying mechanical engineering!

**k14** · 24th October 2007, 09:32

Originally Posted by steveb64

...and there's a pulley question where they reckon there's NO difference between a straight lift (no pully - lifting directly upwards) and using a single pulley - pulling at either 90 degrees from pulley-load or 180 degrees...

There isn't if you have one pulley, no matter which direction you pull you are lifitng the same weight. There is only a mechanical advantage when you have multiple pullleys an the ropes setup in teh right arrangement.

Oh yeah, i got 82%. That electrical circuit one is confusing, the terms they use aren't really widespread in the industry in NZ.

**imdying** · 24th October 2007, 09:40

Air is being pushed into the motor by air pressure. It it only filled due to sucking, then something like a supercharger sitting across the inlet tract would be a restriction. A supercharger works because it pumps more air into the motor. I'm surprised anyone would quote 'howstuffworks' as an authority on anything!