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Operation Problem with breaker

Hello! Motor works OK but chisel seems to jam and stop moving. Motor continues running. No odd noises. Chisel easily removed and refitted. Have taken whole assembly apart and all looks OK. Wondered whether it might be worn piston O rings reducing pressure causing it to stall. Machine is ex-hire and pretty old. Cheers Ron

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  • ronandkate Dec 08, 2008

    Will get some proper grease and give it a go. Thanks!


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I worked at a tool rental /hire while going to college and repaired many of these breakers. For this tool to work most efficiently, we would store them in their stand upright in a heated area (during winter). This tool requires special grease sold as a service kit which includes orings and bolts for retainer area. Remove large piston attached to connecting rod and remove inner striker (fits inside main piston) this striker is the source of problems. Clean inner cylinder and striker and lube with bosch grease, not too much. If you lay the hammer down or store with bit side up this striker will migrate to uppermost part of the main piston and be vacuum locked thus not hammer. Also remove and lube the impact bolt and look for damage. If chipped or cracked this part must be replaced. Parts/list are available at enjoy

Posted on Dec 08, 2008

  • simon jackson Jan 22, 2013

    how hard are these to strip down and clean andif vacumed locked is this the only way

  • John Trevino Jan 22, 2013

    Hammers are easy to take apart and clean. Sounds like the lower part of hammer could be packed with grit not allowing parts to move. Good that the motor sounds good and strong.


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