Truck exam questions

[dazzdillinger]

Please help me answer these questions as i cannot find the right answer anywhere.

I have taken the truck exams three times with results as follows, 67% 64% and 67%. i need 70% to be certified as a truck mechan ic.

1. A hydraulic lift system has a diameter of 6 inch and a 500 psi. how much force can it lift? a. 2 tons, b, 7 tons, c, 14 tons, d, 36 tons.

Please show me the formula as the numbers might change.


2. Drive shaft lenght are measured from cup to cup. A slip yoke drive shaft is measured with the slip extended or retracted?

3.If you replace an ac compressor clutch, do you evacuate the ac system?

[DRKM]

Hey.

The first one is basic Physics.

Force= (pressure)(Area)

2) You measure a slip yoke drive shaft fully extended. What sense would it make if you ordered them retracted? Unless you gave the length of the slip yoke individually... I just mean in tems of ordering a new one.... But generally they are measured fully extended.

3) At every shop I have worked at I have never seen anyone disasseble an ac Compressor. Haha. Anytime a clutch goes we just order a new compressor....

But I am pretty sure that you could replace the clutch without evacuating the entire system. Since the clutch is the switch for the ac compressor...

ANyway I hope that helps. Good luck on your test!

[RickDaTuner]

when you replace the clutch on an ac compressor you do not need to evacuate the ac charge heck you done even have to remove it f from the vehichle just remove the acc belt and swap out the clutch.

The slip yoke drive shaft iirc should be measured at half its length, but I would have to reffer to literature on that one.

And pascals law above is correct

[BerserkerCatSplat]

Keep in mind that Area in Pascal's Equation is calculated by A=pi*r^2, where r=diameter/2 and pi=3.14.

[ExtraSlow]

Just to fully lay it out for you, and putting together what the above posters have said.
if it's 6" diamerter, that means it's 3" Radius. Area = R^2 * Pi
Area = 3^2 * 3.14 = 28.26 in^2
Force = Area * pressure
Force = 28.26 in^2 * 500 lbs/in^2 = 14,130 lbs = ~7 tons.

The full formula is Force = pressure * radius (squared) * Pi.