Cylinder for post knocker

[GazCro]

I have the left aux line hooked up to the top port on the cyl, no lines and open ports on the bottom of cyl. I replaced the elbow that connects the a6 hose to the valve body with a tee. New tee end goes to 1/2 hose to 30gpm diverter valve. 12v to solinoid opens it and dumps into tank return. Setup exactly like Tak parts diagram, just uses elec instead of manual.

Press the left side of pedal to apply force to retract cyl and raise the weight.
View attachment 22170

Don't know why you are messing with hydraulics on digger you shouldn't need to. Whichever way you press the hammer pedal the opposite service will return to tank. So if you're pressing pedal left to raise ram pressing pedal opposite should drop it. I just think you've got too big a ram.

 

[Keif]

Don't know why you are messing with hydraulics on digger you shouldn't need to. Whichever way you press the hammer pedal the opposite service will return to tank. So if you're pressing pedal left to raise ram pressing pedal opposite should drop it. I just think you've got too big a ram.

I did it like this because no USA 216 comes with the hammer valve. I got the part #s from a german manual and Tak usa didn't even have the # in their system much less prices or an estimated date of availability. Better to have it and not need it than to need it and not have it. At least that's what I'm telling myself to make up for all the time I've spent on it

 

[GazCro]

I did it like this because no USA 216 comes with the hammer valve. I got the part #s from a german manual and Tak usa didn't even have the # in their system much less prices or an estimated date of availability. Better to have it and not need it than to need it and not have it. At least that's what I'm telling myself to make up for all the time I've spent on it

Surely they come with an aux circuit

 

[V8Druid]

I have the left aux line hooked up to the top port on the cyl, no lines and open ports on the bottom of cyl. I replaced the elbow that connects the a6 hose to the valve body with a tee. New tee end goes to 1/2 hose to 30gpm diverter valve. 12v to solinoid opens it and dumps into tank return. Setup exactly like Tak parts diagram, just uses elec instead of manual.

Press the left side of pedal to apply force to retract cyl and raise the weight.
View attachment 22170

and the right side to open the spool to allow oil back from cylinder with the solenoid activated to dump the alternate/right side service to tank together with the flow from the ram emptying.
as said though, the larger the diameter of the ram the more damping you are going to get from the oil being expelled ...... what size is the port through which the oil has to escape .... filling is no issue .. has machine working pressure, but emptying, it just has the force exerted by your weight emptying it, so the larger the port the better
my FLT set up is 1/2" ports with an entire fork mast (and whatever is on it) expelling oil from the lift ram to tank

 

[V8Druid]

Don't know why you are messing with hydraulics on digger you shouldn't need to. Whichever way you press the hammer pedal the opposite service will return to tank. So if you're pressing pedal left to raise ram pressing pedal opposite should drop it. I just think you've got too big a ram.

he's "messing with" the hydraulics cos his aux is two way/double acting only Gaz .... to get a free flow back to tank he has to convert to one way/single acting and dump the flow from the second action to tank .... Keif put up a Tak. diagram which shows you how (with a mechanical valve - he's just made it an electrically operated valve for ease) .... no question that the size of the ram (and it's ports) will affect the speed at which the oil is expelled and the level of damping it inadvertently creates

 

[GazCro]

he's "messing with" the hydraulics cos his aux is two way/double acting only Gaz .... to get a free flow back to tank he has to convert to one way/single acting and dump the flow from the second action to tank .... Keif put up a Tak. diagram which shows you how (with a mechanical valve - he's just made it an electrically operated valve for ease) .... no question that the size of the ram (and it's ports) will affect the speed at which the oil is expelled and the level of damping it inadvertently creates

Yes his is a two way circuit (so is my 219) but they drop the pressure from the line you're not using when using the opposite. If he's connecting both sides of the ram to his aux lines it'll never drop fast enough. If he only connects the line he needs it would work however the amount of oil in the ram is gonna spoil that.

 

[V8Druid]

Yes his is a two way circuit (so is my 219) but they drop the pressure from the line you're not using when using the opposite. If he's connecting both sides of the ram to his aux lines it'll never drop fast enough. If he only connects the line he needs it would work however the amount of oil in the ram is gonna spoil that.

yeh he's only got the one side connected ... but he did not have the single acting facility factory fitted, hence having to alter his plumbing ...... and agreed .. a big volume of oil to expel is going to damp the free fall action especially with a 2:1 mechanical disadvantage of two falls of rope

 

[GazCro]

yeh he's only got the one side connected ... but he did not have the single acting facility factory fitted, hence having to alter his plumbing

It should dump that line though, albeit through the valve block but it should work a post knocker.

 

[V8Druid]

It should dump that line though, albeit through the valve block but it should work a post knocker.

sort of .. but you'm dead ending the alternate service, which'd set up back pressure in the spool

 

[GazCro]

sort of .. but you'm dead ending the alternate service, which'd set up back pressure in the spool

But it doesn't affect it. I have post knocker for 8 tonner and it uses only one line (flow or A)and doesn't matter whether tap on return line (B) is set to single or double acting it works either way.

 

[V8Druid]

But it doesn't affect it. I have post knocker for 8 tonner and it uses only one line (flow or A)and doesn't matter whether tap on return line (B) is set to single or double acting it works either way.

interesting .... mine don't like it without the open/free return to tank -- same issue setting up a single acting tip circuit on a duck ... gotta free dump the second action / way

 

[GazCro]

interesting .... mine don't like it without the open/free return to tank -- same issue setting up a single acting tip circuit on a duck ... gotta free dump the second action / way

I still open return to tank tap but it isn't necessary. 219 doesn't have tap for free return but is perfectly happy running breaker so they've likely got it sorted

 

[GazCro]

You usually have more problems with machine with only single acting circuits as they often don't have the option to dump oil back down the flow line.

 

[Storrsy]

But it doesn't affect it. I have post knocker for 8 tonner and it uses only one line (flow or A)and doesn't matter whether tap on return line (B) is set to single or double acting it works either way.

This is my experience of my Kubota too which doesn’t have single acting. The post knocker works fine, it just doesn’t sound very nice.. I think @doobin reckoned an easy way of overcoming this is to simply T line B in to line A so that when you release the hammer weight in double acting mode the fluid in line B goes back through line A along with the fluid from the knocker ram....
@Keif what size is your hammer on the knocker?

 

[Shovelhands]

As has been said, your cylinder is probably oversized. But you say it didn’t free fall with everything disconnected? So you were just dumping oil into a barrel/can?
Have you checked the physical size of the drilling/hole in the cylinder barrel, where the threaded part is welded to the cylinder? This drilling may be far smaller than the fitting itself and could be acting like a flow restrictor? Also, if I’m correct, you are supplying the oil to the Rod side of the cylinder? If so, also check the gland is not restricting the port in any way. I don’t know how your cylinder is constructed, but wouldn’t be the first time I’ve seen the port drilling in slightly the wrong place and the gland actually obstructing it!

 

[Keif]

I still open return to tank tap but it isn't necessary. 219 doesn't have tap for free return but is perfectly happy running breaker so they've likely got it sorted

I "think" the USA and euro machines come slightly different because if the prevalence of hyd thumbs over here. Machines come with the cast thumb mount and valving to make it hold.

 

[Keif]

This is my experience of my Kubota too which doesn’t have single acting. The post knocker works fine, it just doesn’t sound very nice.. I think @doobin reckoned an easy way of overcoming this is to simply T line B in to line A so that when you release the hammer weight in double acting mode the fluid in line B goes back through line A along with the fluid from the knocker ram....
@Keif what size is your hammer on the knocker?

Right now it only weight around 90lbs because the I haven't filled it with ballast yet.

 

[Keif]

As has been said, your cylinder is probably oversized. But you say it didn’t free fall with everything disconnected? So you were just dumping oil into a barrel/can?
Have you checked the physical size of the drilling/hole in the cylinder barrel, where the threaded part is welded to the cylinder? This drilling may be far smaller than the fitting itself and could be acting like a flow restrictor? Also, if I’m correct, you are supplying the oil to the Rod side of the cylinder? If so, also check the gland is not restricting the port in any way. I don’t know how your cylinder is constructed, but wouldn’t be the first time I’ve seen the port drilling in slightly the wrong place and the gland actually obstructing it!

Thanks for the suggestions. I took the line off of the cylinder and the port to top of ram necks down and is definitely a restriction. Also the fitting on the 3/8th hose I had made probably only has a 1/4 passage...so it looks like both my cyl port and hose from cyl to machine are restrictions.

That being said,

I finally found a hydraulic site that lists the internal volume of cylinders. The one I have is almost 3qt volume. I think replacing it with one with .37 of a qt will make a huge difference!

Thanks for all the help.

 

[Keif]

Finally got the new baby cylinder in(snow/ice storm help everything up) and it works, gravity ain't no joke!

 

[Storrsy]

Finally got the new baby cylinder in(snow/ice storm help everything up) and it works, gravity ain't no joke!

Glad you got it sorted- you’ll wonder how you managed without it. Are you making it so that you can press down on the post with the post cap like the vector one? I’ve been running knockers in different guises off diggers for 11 years and in my experimenting find the ones without the leg are the easiest to use as it works like the vector one so the digger boom doesn’t bounce every time the weight goes up.