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Alveprins

Power hammer problem - Hammer keeps falling...

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Alright - so I was drawing out this multibar damascus billet today, I turn from the gas forge to the hammer - and what do ya know - the hammer is already out - even though I haven't even touched the damn thing... Next thing - the hammer slowly keep sliding further and further down until it eventually hits the anvil surface.

I turn it off and open the cover over the rear piston - and test it by putting in some oil directly - and starting it again. It performs better - but still can't pull the hammer all the way up into it's chamber - and still slowly keeps falling down closer and closer towards the anvil.

Is this a gasket problem - or has the piston become so worn - it is no longer able to keep sufficielt vacuum / pressure or whatnot to keep the hammer all they way up?
I did a quick check of the lever that lets in air and stuff in order to make the hammer go - but nothing seemed loose or anything... everything solid and tight as usual.

 

I've attached links to a couple of short clips of the hammer in action onto YouTube so that the problem can be seen visually:

From distance:

Closeup:

Any help and input is greatly appreciated! I have this guy waiting patiently for his knife - and I need to resolve this problem ASAP. :unsure:

 

Sincerely, Alveprins.

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7 minutes ago, Brian Myers said:

Looks like a gasket problem. Have you noticed any excess oil leaking out? 

Not really excessive... rather ordinary actually. The oil leakage has been increasing as the hammer gets warmer though. So in the start there is no leak, then after .. say.. 2 hours - puddles start to form on the anvil surface rather rapidly.

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Might be worth allowing it to fully fall and examine the ram thoroughly for any deep scratches. A good sanding may help but likely gasket as Brian said.

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4 minutes ago, James Higson said:

Might be worth allowing it to fully fall and examine the ram thoroughly for any deep scratches. A good sanding may help but likely gasket as Brian said.

I suppose I could take the ram out (never done that) and have a closer look at it.
I have also contacted the factory - and I suppose I will get some feedback tomorrow when it is daytime in China. :)

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You don't necessarily need to take it out. I let it fall fully to the anvil and then sanded the scratches off in situ.

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1 minute ago, James Higson said:

You don't necessarily need to take it out. I let it fall fully to the anvil and then sanded the scratches off in situ.

Ah! I've already let it fall fully to the anvil face - and there arent any apparent scratches or anything on it. :)

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That's good. Scratches usually mean it's rubbing the cylinder wall. Sounds like a broken or worn out gasket somewhere letting the vacuum drop in the ram cylinder letting the ram drop. 

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7 hours ago, Brian Myers said:

That's good. Scratches usually mean it's rubbing the cylinder wall. Sounds like a broken or worn out gasket somewhere letting the vacuum drop in the ram cylinder letting the ram drop. 

Alright. :)

So - I suppose now the question is: Is it the rear piston, or the front ram that has faulty gasket? ... Which one is most prone to wear if I may ask - anyone know? ^_^

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What did TZ say ? if you move the handlever a bit is there a position that the tup stays at the top ? most likely to be mechanical wear to the faces that meet to arrest the valves in a certain position to keep the the 'top setting' position (or floating ram or what ever they call it in chinglish). If you can find a handlever position where it stays at the top you will need to adjust the faces by welding up or whatever.

There are no gaskets in the hammer that would cause this. I dont know where that information has come from.

Piston rings, maybe. 

The Teng Zhou hammers I have seen were constructed to such a terrible standard nothing would surprise me when you get into it a bit.

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On 30.11.2017 at 11:26 PM, John N said:

What did TZ say ? if you move the handlever a bit is there a position that the tup stays at the top ? most likely to be mechanical wear to the faces that meet to arrest the valves in a certain position to keep the the 'top setting' position (or floating ram or what ever they call it in chinglish). If you can find a handlever position where it stays at the top you will need to adjust the faces by welding up or whatever.

There are no gaskets in the hammer that would cause this. I dont know where that information has come from.

Piston rings, maybe. 

The Teng Zhou hammers I have seen were constructed to such a terrible standard nothing would surprise me when you get into it a bit.

Talked to the factory - and they said it is most likely worn gasket - or as you more properly put it - piston rings.

They told me to grease up the front of the hammer where the ram goes in and out - and test it. The ram was pulled up much further than before - but not all the way in. Almost though. As I let the hammer idle - slowly it started sliding out again.

I suspect piston rings on the ram itself are worn - and thus leaking air. I will replace them tomorrow.

 

About replacing them. From which side should I remove the ram? Top - or bottom? :huh:

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Alright - I've opened the hammer and done some horsing around...

First thing I did was to change the piston rings of the ram itself. - No effect.

So I proceeded to opening up the hind part of the hammer - disconnecting the driveshaft from the rear piston - and pulling the whole thing out.

Now - when I first removed the ram from its cylinder - I noticed a little broken screw at the bottom of the cylinder. I didn't think much of it until I pulled out the rear piston and noticed a screw missing there:

Cylinder001.JPG

Clearly at some point one of these two screws holding the gasket / piston ring / whatever-it-is-called together down there got loose - and blown into the ram cylinder. Meanwhile - the part previously being held in place by it has been loose - letting in air.

Screw001.JPG

So - this I suppose - is what I need now:

Screw002.JPG

A new screw to properly secure this.. whatever it is called; properly in place. :)

 

I will be changing the piston rings for good measure too though - since I've already pulled out the thing.

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Looks like a cross between a piston ring and a bearing and race. 

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Its a spring loaded cast iron wiper, sort of the opposite of a piston ring, as it pulls in against the rod with pressure from the spring, rather than pushing out against a cylinder liner.

I do not think the 'assembly screws' coming loose will affect the performance of the hammer. They are only in there to allow it to be assembled. When I have been in a bind before I have just used 1/2" of matchstick to hold it all in place when the piston is re-assembled, with the reasoning that when it works its way out, 1/2 a matchstick will not damage anything.

Once the piston is in position, the wipers can not collapse inwards, hence it just being an assembly screw.

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20 minutes ago, John N said:

Its a spring loaded cast iron wiper, sort of the opposite of a piston ring, as it pulls in against the rod with pressure from the spring, rather than pushing out against a cylinder liner.

I do not think the 'assembly screws' coming loose will affect the performance of the hammer. They are only in there to allow it to be assembled. When I have been in a bind before I have just used 1/2" of matchstick to hold it all in place when the piston is re-assembled, with the reasoning that when it works its way out, 1/2 a matchstick will not damage anything.

Once the piston is in position, the wipers can not collapse inwards, hence it just being an assembly screw.

Now I finally know what that thing is called - as well as the exact function of the screw. :) Thank you Sir!

Well, I will change the rear piston rings as well, and I suppose I can change the "spring loaded cast iron wiper" as well - since I have an extra of those. That way there will be new "everything" both in regards to the rear piston and the front ram.

 

If the hammer still has problems after that - I am not quite sure where to look further for a problem though... :unsure: But we will see! ^_^

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You might find the performance of the hammer worse with new piston rings. It takes the rings a long while to 'bed' against the insides of the cylinder. You will witness this on the old rings / wipers with their 'wear' pattern, which is really just bedding.

IIRC your hammer is only a couple of years old, occasionally used ? it should just be at the 'bedding in point' not replacing them point, that should be 15 years in the future !

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What brand of power hammer is this?

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1 hour ago, John N said:

You might find the performance of the hammer worse with new piston rings. It takes the rings a long while to 'bed' against the insides of the cylinder. You will witness this on the old rings / wipers with their 'wear' pattern, which is really just bedding.

IIRC your hammer is only a couple of years old, occasionally used ? it should just be at the 'bedding in point' not replacing them point, that should be 15 years in the future !

Now I am starting to get worried...

The mechanics of the machine are simple enough though... If the ram suddenly dropping is not a result of faulty piston rings or wipers, or deep scratches in either of the two cylinders or their respective pistons - then what could it be? The hammer body itself is without cracks or visible damage... The lever / valve that regulates the air seems to be without fault.. I even detatched the lever arm in order to regulate (rotate) the valve freely with my hand - and at no point was I able to turn it in such a way the ram was pulled completely up into the cylinder... So it's probably not that either.

With such simple mechanics - I am having a difficult time imagening where to look next. (note that this is my first hammer, and I have no previous experience... :lol: )

Could it be that some of the air-intake holes / canals / whats-its-called could be clogged up or something - creating pressure problems?

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44 minutes ago, Jlinner said:

What brand of power hammer is this?

Zao Zhuang Make Machinery

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Given what John N said, and being the primate I am, I'd probably round up all the material I could ever think of hammering, fire up the forge and have a "poundfest" to see if things wouldn't "shake hands"

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The check valve on the lower control valve could be faulty / not seating properly. The valves run through cast iron tubes that are pressed into the frame, one of these might have grabbed onto the valve and rotated a bit in the frame.

The 'ball' check valve ( the one visible when you remove the ram cover) might not be seating / missing / or gasket obstructing the air passage (cut out) that provides the pneumatic buffer to the ram.

The sleeve that the compressor piston runs in might have moved a bit vertically, changing the compression.

The air 'supplement' holes (behind the 2 small square covers on the compressor end) might be obstructed.

Oil has probably got something to do with it, incorrect grade / quantity consistency of supply etc.

It might be a combination of a couple of things :)

Its incorrect to say they are simple machines, the more you get to know air hammers, the more you realise you dont know everything about them !

I've worked on forging machinery 25 years, and still learning a lot about it !

 

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On Wednesday, December 06, 2017 at 2:25 PM, Alveprins said:

Zao Zhuang Make Machinery

Is "Zao Zhuang"  one of the Chinese dialects "Sort Of" ?

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On ‎09‎.‎12‎.‎2017 at 8:42 PM, Vern Wimmer said:

Is "Zao Zhuang"  one of the Chinese dialects "Sort Of" ?

:P Haha! Not quite - Zhao Zhuang is the city name where the factory is located. ;)

If it was "sort of" it would be something along the lines of "cha bu duo" Which directly translated to english would read something like this "More or Less Make Machinery" - which I suppose would be more or less correct... :lol:

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On ‎09‎.‎12‎.‎2017 at 6:21 PM, John N said:

The check valve on the lower control valve could be faulty / not seating properly. The valves run through cast iron tubes that are pressed into the frame, one of these might have grabbed onto the valve and rotated a bit in the frame.

The 'ball' check valve ( the one visible when you remove the ram cover) might not be seating / missing / or gasket obstructing the air passage (cut out) that provides the pneumatic buffer to the ram.

The sleeve that the compressor piston runs in might have moved a bit vertically, changing the compression.

The air 'supplement' holes (behind the 2 small square covers on the compressor end) might be obstructed.

Oil has probably got something to do with it, incorrect grade / quantity consistency of supply etc.

It might be a combination of a couple of things :)

Its incorrect to say they are simple machines, the more you get to know air hammers, the more you realise you dont know everything about them !

I've worked on forging machinery 25 years, and still learning a lot about it !

 

Thank you very much for your input Sir, and in retrospect I see that you are correct concerning my initial assumption regarding the lack of complexity in the airhammer design...

I am going to make a checklist and go through it part by part this weekend. I noticed the "ball check valve" as I removed the ram cover - and thought to myself "wth is that? ... " - now I know. ;) I will see if it is stuck or something.

 

Thing is - when this first happened - I was not even touching the hammer... I was staring into the fire when I suddenly heard the hammer stopped making that "Tcht, Tcht" sound (valve air release sound) when idling - and went quiet - like when I pull the lever and inidiate the ram.. only - I was not touching it. And slowly but surely it came sliding out on it's own.

 

I suppose if it was the lower check valve got snagged or whatnot - it should have happened while I was using the hammer - and not idling?

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Hey folks. long time lurker, first post. I wanted to register on here and tell a similar experience that I hope helps.  A lot of the china made self-contained hammers call for SAE 30 wt oil, and when I got my Anyang I powered it up with that.  After a few days I was having this same issue.  At the time I discussed it with my father (machinist) and we came to the conclusion that it was too thick for the temp of our shop.  I drained the 30 wt. and refilled with Air tool oil which is just ISO 32 rebranded. I cranked the oilers up and ran the hammer hard for a hour with some test steel and it hasn't had the issue since. I don't know what oil your using but before a tear down if the rings, wipers, and cylinders looked OK if your not using a thin oil I would give it a try.

-Morgan

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