moments and forces prob

Firstly hi to everybody,totally newbie here.

I will do my profile later on,but i need urgent help

i need to lift a drum which weights 70kgs,using a pneumatic cylinder,how do i choose a cylinder big enough to do the job,ive got the stoke but not the bore.please find attached a .pdf of what im trying todo

thanks

forces.pdf

Not a cad question, but drawn in cad

To determine the force, you need to balance the moments.

M1=M2

F1 x d1=F1 x d2

if the load you're lifting is 70 kg & is at the end of the lever/lifting arm, the moment is

M=325 x 70=22750 kg.mm

To find F at end of 100 mm arm:

F=22750/100=227.5 kg

This neglects weight of the arm itself, if it is sugnificant include it as well. The weight of the arm acts at 1/2 the distance between the end & the pivot point.

bore(Ømm) = 20 x sqrt((70 x 3.25)/P/pi)

where P = pressure generated by hydraulic (or pneumatic) pump (kg/ cm^2)

I guess it was more 'urgent' than we were able to deliver - no reply post and not logged back on since posting

thanks for the replies.ive also put this in another forum,and 4 people have come up with 4 answers.very distrubing

so far the answers if been given are

2231 N

227.5 kg

826.875

298

thanks for the replies.ive also put this in another forum,and 4 people have come up with 4 answers.very distrubing

 

- just goes to show that you gotta do the calculus yourself and run with that answer.

alhtouhg, the two first answers are in the same region, and assuming the last one is in kg., that one is also in the same region - so if your own answer ends up there, it mught be a good bet that it's close if not correct.

Although, I've had hand-ins at school where we all helped each other, all handed in the same answer, and all failed

all handed in the same answer, and all failed

hmmm, I wonder why? LOL

hmmm, I wonder why? LOL

IN my defense, we were suppose to work together - didn't think the teacher counted on everyone helping everyone though

Huh? so he says work as a team and you do, so he fails you??

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OP, i would say go with tigers suggestion as that sound's the more

viable option.

To get the system into equilibrium, you need the force of 227.5 kg or 2231N, as CarlB explained in his post.

But you also asked for the bore of the cylinder. That depends on on the pressure you can generate at the pump supplying the cylinder with gas or liquid.

bore(Ømm) = 20 x sqrt((70 x 3.25)/P/pi)

where P = pressure generated by hydraulic (or pneumatic) pump (kg/ cm^2)

Huh? so he says work as a team and you do, so he fails you??

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nah, he failed us because we all had the wrong answer. No worries though, we just had to do the assignment again (with some helpful pointers from the teacher)