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Kuhn Hammer loosing power

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first of all check if the hammewr is working in its natueral ryhthem 220- 240 bpm
if less then 220 the belts are slipping tighten them or if worn out change them!
if the belt are ok and the hammer is in the right ryhthem (the check is done when u forge a piece of hard wood and not on idle) check while the hammer is working if u have full recovery means if the day light is acc to the book -i think 91/2'' if very much less and there is no full recovery it means the hammer piston is loosing air on the way up and when it is not going all the way up on the way dowen the hammer is not having full valocity and no power-then check the amount of air that is leacking around the silling collar by putting your hand there --be carefull-- if there is a bIg leakeage u have to repair the silling system and get the right parts from the agent.
this happens when not enough oil is oiling the ram allways more oil is better then less .on the kuhn hammer the oil is been SUPLIED with possitive pump and many times the oil suply to the hammer is lesser do increase the oil amount u have instructions in the book. if all this is ok there are two more things to do 1. on the kuhn the unit is a close box the air is going and coming IN AND OUT through a filter if jamm u have a problam of a insuffitient air coming into the hammer and the out let of air is not free!! cleen the filter.
2 if u take the cover away under the cover there is an adjustable left right rode see if on nutral the marks mech if not adjust it again acc to the book.
there are some more things but it is complicate for me to explain on the mail.
hope i helped u some

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I'm attending SIU in Carbondale, and we have one of the new model 50 Kg Kuhn hammers. It's been out of commission for the past three or four years due to the fact that it was losing power, and the rhythm was slowing down. It was losing power to the point that while running, the ram would just stop cycling and sit on the bottom die. It also knocked loudly while running, something that was not coming from slipping belts. All of these problems got worse as the hammer was used. When I finally looked into it (and I was the 4th guy to do so), I noticed that the rod was loose in its bushings on the compressor cylinder (the source of the knocking).

That prompted me to take apart the rear (compressor) cylinder to check on the piston rings. Upon taking the cylinder apart, my first surprise was that everything was bone dry and covered with a black powder mixed with specks of metal. My next (horrible) discovery was that the rings had entirely disintegrated, and that both the piston and cylinder tube had been heavily galled, which was where all those shiny little specks of metal had come from. It looked as though someone had taken a chisel and incised the entire circumference with rather heavy grooves.

Now from what I can tell, there was never an oil line that ran to the compressor cylinder. The only oil line on it goes to the ram cylinder. The dealer at Centaur Forge that I've been dealing with says that the rear (compressor) cylinder does not require any oil due to the materials the rings are made of. Note that this cylinder is an aftermarket component that Kuhn buys ready to go from another manufacturer. However, it seems that a lack of lubrication in the cylinder was the source of the failure. Nevertheless, we are awaiting the arrival of a brand new compressor cylinder to get the hammer back up and running. Once its installed, we are thinking about running an oil line to the compressor cylinder to keep this problem from happening again.

Your hammer may very well be starting to experience the same symptoms as the one at school. I've heard that other smiths who have these newer models have also experienced similar problems. Check it out ASAP before any major damager gets done!

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  • 6 years later...

Hey ya'll.  This is a very old post but I am dealing with this issue now with my Kuhn Kcf 50 and was curious what was the outcome. I just changed the piston rings to the ram and will drop it back in tomorrow morning but I have a really bad feeling its the compressor.  I have an email out to Georg Kuhn to see what he says but was wondering if any of you guys are still on here and if there was an answer and a $ amount...new compressor doesn't sound like a cheap fix..and I want to know if someone ran an oil line to theirs because mine doesn't have one and I always thought that was BS...Centaur Forge was zero help since the day it was delivered 11 years ago

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Sorry to hear of your problems, hope you get them sorted.

I have a 50kg Reiter which like swedefiddle's has a drip oiler on the compressor cylinder. It drips the oil which is drawn into the cylinder and is then carried by the air through the valves to the ram cylinder. So on those later Kuhn enclosed hammers as long as oil gets into the air system somewhere it should get carried around just the same I would have thought.

After ten years mine suffered from slipping drive belts because I rotted the rubber by over-greasing the main bearings, I haven't changed the maintenance schedule and will quite happily pay for a new set of belts every ten years if it means everything else keeps going well.

The only other problem I have now and then, is the blow-off valve sticking open due to gumming up by over-oiling. This causes the tup to get above the inlet and not come down. Fix routine is:- Turn off the motor, pedal down, start motor again when the tup has fallen a bit and keep slight pressure on the pedal to keep it cycling. Finish the job, then strip and clean out the valve in the evening.

According to the book, with the oiler set correctly it should use an oiler full every eight hours. I stick a chalk mark on the wall every time I fill it up and then every fifth time go round with the grease gun. The handbooks suggest greasing every week so I reckon every five oiler fills is the equivalent for intermittent use.

Presumably if you have been replacing piston rings you have already stripped and cleaned everything else. If not...On your Kuhn is there an internal exhaust filter system, or is just that the oily air is retained within the enclosure? If it does is the filter clear? Have you checked that the one way / blow-off /spring plate valves inside are sealing /seating okay and not stuck open or closed? I presume it has them similar to my Reiter.

The early models like mine were really noisy on standby and were constantly pumping out oily air. When I saw the improved enclosed ones I modified mine by routing the inlet and exhaust into a plenum chamber and it transformed the machine...so much so that I did the same with both of my Alldays hammers, well worth it.

Good luck with it.


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