[FW] Hydraulic Crusher Bot

[Gabe01]

if you're going to use the rams it came with, I think you'll bend the rams before you bend hardox. get yourself one fat ram.

[maddox10]

Crusher norm for feathers. No clue
Ram power ain't the main thing. Pressure on the tip is what counts, combined with the shape of the tip.

Also, stroke and speed have their place.

The 20mm rams, what stroke are those? If the stroke is longer than 40, the forces impared in robot combat will bend the rods.

On the other hand, Tiberius uses a 70*148 ram, with a 20mm hardened steel rod, and it seems it's still going strong, even build by me in 2003.

[Giles]

Hmmmm yes the rams are extremely light, which leaves me to wonder what they are made from... The big rams have a stroke of 140mm, was planning to use these on a 3:1 lever ratio to help with grabbing speeds.
Will look into sourcing a single, fat ram. 32mm would be ideal. I'll see if anything crops up on ebay that will fit the bill.

Is there a standard in how to prevent the pump from overworking when the ram is at its full extent? The rams i'm using at the moment are sensored, but I can't imagine many second hand rams on Ebay having such features.

EDIT:
Something like this seems to fit the bill.
http://www.ebay.co.uk/itm/Flowfit-Hy...item3a7cb3126c

[maddox10]

That one will be heavy.

To avoid burned out motors or burst parts, an PRV or current limiter is in order.

[Giles]

Just wanted to test out the rams/pumps under load to make sure everything worked as expected. Seems to be working fine. Will need to explore the strength of these rams though until I can find a good 32 bore one which isn't too heavy (suggestions anyone?)

[maddox10]

What stroke is wished for?

[Giles]

Anything between 100mm and 140mm would fit well into the current design. We currently have two 80mm ones (as seen in video) and two 140mm ones. Wouldn't really want anything longer than the 140's.

[overkill]

The 20mm rams, what stroke are those? If the stroke is longer than 40, the forces impared in robot combat will bend the rods.

What about if the rams are pulling in, rather than pushing out?

[maddox10]

Then the rod size will detract from the power. Bore 20mm, rod size 12mm

1*1*pi*120bar=376.8kg of force pushing.

Pulling it's (1*1*pi*120) - (.75*.75*pi*120)= 165,85 kg


But in tension steel is better than in compression. One of the reasons we have longer suspension bridges than single arch bridges.

[overkill]

OK, so if the bore cross section is smaller, then the ram will be moving faster for the same pump flow - couldn't the leverage ratio on the jaws be changed to make up for the lower force while keeping the closing speed about the same?