"Scott Vernon" wrote in message
...
|
| "Capt. Mooron" wrote
|
| Quit toying with the damn boom.... look think of it this way... how
| many
| lifting devices utilize a support located under the boom at less
| than 25% of
| the boom length? NONE!
|
| Wrong, kanook.
| Have you never seen an engine crane?

Is the brace located at 25% of the arm's length? I believe the hydraulic ram
is located at 50% or more of the arm length.

| A bascule type draw bridge?

It's only lifting the bridge [boom] .. and again not at only 25% of the span

| Any hydraulic crane with the boom out?

Not at less than 25% of the boom.... extend the boom and the capacities
decrease exponentially.

| An excavator?

Double Hydraulic rams to the main boom at 50% distance or better to the
elbow and a third along the top of the stick to control breakout and curl.
Limits imposed are with bucket size and hydraulic capacity.

|
| need more?

Sure... the examples you provided so far hasn't done anything to convince me
that the capacity of a lifting device secured to a location less than 25% of
the span of the boom can lift as much as one located at the end of the boom.

Make note I never claimed a device secured to the bottom couldn't lift a
weight... only that the location of the vang in this instance is far too
short to accommodate the capacity of a topping lift.

Look Scotty... if you place a pair of hydraulic rams to the end of the
boom.... or a distance greater than 50 % of the span.. then the issue
becomes moot. The specific point I'm making is that the rigid vang is badly
situated to handle loads delivered to the end of the boom.

I'll stand by that claim...

CM