Grappling fun - A Picture Thread....

Threepoint · Oct 11, 2015

k0ua said:
I think so. Here try this experiment. On you garden hose turn the water flow down to just a drip by nearly closing the water valve. Now lest say the water pressure on your system is 60 lbs. Now just a drip ever few seconds is coming from the hose. Put your thumb over the end of the hose, wait several seconds and you will start to feel the pressure building under your thumb. After some time the full 60 lbs per square inch will build up under your thumb. The flow rate of the flow is very very low, just a drip, but it will still develop the full 60 lbs per square inch under your thumb, it just takes a long time to do it. If a small amount of water leaks past your thumb, it will take some time to develop the 60 lbs again, but it will happen.

So the "flow restrictor" of the water valve nearly shut slowed the flow rate down to nearly nothing, but it still delivers 60 lbs per square inch of pressure over a long time period, at nearly zero flow rate.

Nicely explained, James! Your experiment would make Bill Nye The Science Guy proud! :thumbsup:

Threepoint · Oct 11, 2015

Xfaxman said:
That is correct, but I am also confused by the term "pressure drop". From my experience, in an open center system, pressure increases with resistance to flow. Instead of "pressure drop", it is "flow rate decrease"

When the grapple lid stops moving, pressure will increase until the relief valve opens. That is maximum clamping force.

Seems like the confusion in terminology is just over where we are measuring when we talk about an increase or drop in pressure. Restricting the flow causes the applied pressure to rise at the point of restriction, but results in a corresponding drop of applied pressure measured at the cylinder downstream, until the volume of fluid passing the restriction catches up to the original flow rate. James' experiment with the garden hose illustrates that.

Gordon Gould · Oct 11, 2015

Thanks K0ua. Easy to understand that.

gg

IslandTractor · Oct 11, 2015

Bottom line, the output from a 1/4" line is perfectly adequate to operate a grapple cylinder. I use 3/8" because it is tougher than 1/4" and more flexible than 1/2". The last 18" or so are 1/4".

mrtwister · Oct 12, 2015

From the bush to the mill....white spruce dead-fall.....grapples are great!!

13 foot log going down an 8 foot wide bush road makes things interesting:

....and finally on the mill:

sd455dan · Oct 12, 2015

Knocking the dirt out of the newest stump by lifting and dropping it and then grapple holding it to square cut the top-

This one was heavier than most

grapples are the best

here is a pic of the tree- the stump was attached to before i dropped it

kminnick · Oct 13, 2015

Hi sd455dan- I assume you missed your shop?

sd455dan · Oct 13, 2015

Yeah-

it's still intact,
I thought about having it done professionally but we had already removed several other shorter/smaller trees using the same method. So just went for it, gotta say i didn't need any coffee during or after:laughing:

I posted about it over on the tractors and wood thread- using a long heavy duty cable/ rope setup hooked to the JD dozer and then wedge /hinge cutting the tree and pulling it over.

Here is the grapple picking up the base of the tree where it landed

Wife did video it on her phone -but not sure how to post it without linking to her facebook page..??.

Xfaxman · Oct 13, 2015

Steve_Miller said:
I had to take it off because it caused too much damage.

Steve

Xfaxman said:
Neat scale. I am guessing that is a half ton. Have you ever weighed it?

My 3/4 ton GMC weighs 7300 pounds, front axle 4100, rear axle 3200.

seems kinda light for the back half of the truck.

94BULLITT said:
By picking up the backend he is transferring some of the weight to the front axle.

Steve_Miller said:
I think it is somewhere around 4500lbs. 05 Silverado Z71. Roger is correct, I would not be able to lift the front end at all.

----------------------

Steve

Xfaxman said:
I'll have to try it with my truck and see how it compares to the weight on the axle.

I had the crane scale on and remembered these posts from last year. My truck has been weighed at the Co-op, front axle, 4100 pounds. Rear axle 3200 pounds.