Emergency stop for a machine with valves and cylinders

[HDG]

a)Design and draw a circuit using the cascade system to operate 2 cylinders (A&B) which, on the operation of the start valve produces the sequence A- B+ B- A+. The cylinders should park in the positions B- A+ when the start switch is in the off position

b)Modify the circuit designed for part a) to provide an emergency stop which will park both cylinders in the extended position (i.e. A+ B+)

I'm ok with part a) and satisfied that the circuit I have drawn is correct. I am, however, struggling with part b). The learning material given is literally 2 pages long and doesn't seem to provide enough info on how to answer the question correctly. It only states how an emergency stop will work with 1x cylinder and not 2!

Looking at the info provided I am thinking that the emergency stop can only really be placed in one place - on either side of the 5/2 changeover valve. One side will block a1 (selects group 1) and the other side will block b1 (selects group 2). The issue I'm having is that if it does go in this position then the cylinders will not both be in the outstroke position (A+ B+). Is anyone able to give me a nudge in the right direction please?

thanks

 

[donpacino]

Looking at the info provided I am thinking that the emergency stop can only really be placed in one place - on either side of the 5/2 changeover valve.

We can help if you provide us with the information and your solution to part A

 

[HDG]

 

[HDG]

Sorry didn't think you were supposed to upload answers etc

that's my attempt at part a). I want to put the emergency stop in between a1 and the 5/2 changeover valve and b1 and the same changeover valve but I can't asee how this will make cylinder b outstroke (B+)

 

[HDG]

 

[HDG]

This is the emergency stop system I need to try and incorporate into my answer.

.

 

[batesy71]

Hi

I know its been some time since this thread, but I don't suppose I could ask for a hint, as I'm stuck on the same part.
After looking at the notes on the emergency stop, I believe it should be integrated with the two 5/2 dcv's supplying the cylinders.
Does this sound right?

Alan

 

[Rodgers]

Did either of you lads get the answer to this? I’ve got the same question just in A+B-B+A- think I’ve got the drawing done just don’t know where to put the emergency stop.

Thanks
Liam

 

[Rucksack]

Did either of you lads get the answer to this? I’ve got the same question just in A+B-B+A- think I’ve got the drawing done just don’t know where to put the emergency stop.

Thanks
Liam

Liam,

Did you get anywhere with this?,

Thanks.