Hitachi Hammering - Popular Questions, Answers, Tips & Manuals

they usually heat shrunk on, to remove it you will probbley damage it.

A vise is a must (do a safety goggles) hard steel on hard steel can deliver hot splinters at this job, put it the chisel with the machine fixed cross in a vice place the chisel lock on the machine open and slam a fist hammer slowly machine of the tool down.

OIL ?? I think Hitachi has always a yellow grease lubrication hitachi grease demolition hammer Google zoeken never seen heart of oil in Hitachi demolitions. but there could be models in your Country thats new for me . Otherwise BOSCH HILTI and the one and only brand DUSS demolition hammers and also a few brands of Chinese hammers need oil lubrication . an expensive sinc-free hydraulic oil the same as used in some pressure washers life lasting oil but for HItachi look at the link for the grease 2 tubes a enough . good luck and dont forget the piston pin to replace with a new not only the gaskets and o-rings and also the oil and dirt seals on the front where the striking pin is that must be absolutely not air leaking because all your work burns in a few months again out . you can start all-over again.

http://www.manualslib.com/manual/777939/Hitachi-Dh-40mr.html

It can also be a suppression capacitor by the switch , or the electric field itself one or both coil fiels are gone.

Try just stopping and starting the machine off a while.to see if the hammer appears.

Remove chuck assy and see if it will release, it might need a bit of help with a vice. If not then it will have to be taken apart and pressed out.

Could be dirty, or could be wearing out.

There is a sight glass on the side for you to see the oil level. Make sure they are always checked. You can buy the oil at any service center. Hilti makes oil too and can probably be purchased at Home Depots. Also the Home Depots that have tool rental programs would most likely sell the Hitachi oil too.

Hitachi hammers use 30wt non detergent oil. But you can use lighter oil in cold climate. If too much oil accumulates in hammer, it may just come out bit retainer or build-up inside gun. Oil enters the hammer by wick process, of wick is missing oil will enter too quickly. If your brand label is glued on, you may have a hitachi copy from china (most hitachi labels are rivited on). China hammers may use different oil.

Your hammer uses an air cushion created by drive piston to move a driven piston which contacts a second piston or striker. The second piston or striker is the part that contacts the bit. The striker can become restricted from moving to its full limits by debris or just worn slightly shorter (the part of the bit that enters the gun can wear shorter also ). Lack of movement due to debris or shorter length due to wear will cause weak hammering action. Assuming the bits are not worn where they enter the gun, as you push the bit all the way in into the chuck, the bit moves/pushes the striker into position close to the driven piston. The driven piston receives its power/movement from good vacuum between the driver piston. Good vacuum is created when there is good contact with orings to cylinder and good clean lubrication (Use Hitachi gear/hammer grease). As the grease heats up, it will run out of the cylinder. Good clean grease will remain in cylinder even after heavy use. Dirty grease and loose orings will loose power/vacuum to driven piston. You stated that you have different hammering action depending on position indicating that pistons are loose in their cylinder. The hammer should be stored with the nose pointing downward after use so that the driven piston will stay at the end of the cylinder and not slide against the driver piston (when the grease is hot, the driven piston can slide against the driver piston and will take longer to begin hammering).

I have seen many versions of this hammer with many different mfg names. I believe that this is a China copy of a hitachi hammer. No parts are available for this tool. The tool looks substantial from the outside, however internal parts are weak and break/burn out very easily (unlike the Hitachi/Japan version which is a workhorse, years of use before failure). If your hammer is china version, do not invest any more money because other parts will start to fail (most fail within short time from motor burn or broken parts ).

For most climates a good oil to use is air compressor oil (mineral). Sold at Lowes and many other stores. It has great lubrication properties and can take good amount of heat. In very cold climates where oil could thicken, store hammer indoors to keep warm until ready to use. Good luck

Demo hammers do not oil/grease the bit. The grease in the tool is to lubricate and cool the parts in there doing the hammering. The bit should have grease on the end going into the hammer to make it work in the tool better and make it easier to take out when you are done. You have to put the grease on the bit yourself.

Large hammers have an air driven piston (an air cushion betweem pistons) and an intermediate anvil that actually hammers on bit. If the cylinder and air cushion piston are dry there will not be enough suction/pressure between the driver piston and driven. Remove lower part of hammer and lube with electric hammer grease. Make sure that orings fit snuggly and the anvil is not jammed. Do not store hammer with the bit pointing up because the driven piston will slide down cylinder and hug driver piston. If the hammer was stored pointing up, turn hammer around and place in stand with nose down in a warm location so that the driver piston will drop into place. Good holidays

Insert sds bit into chuck with slots/slot matching slot in chuck while pulling back on the spring loaded nose. If the bit does not catch try turning/rotating bit to lock. When you release the nose, a pin will drop into the indention on bit and prevent it from falling out during use. Sometimes this pin will break or wear-out thus the bit will not catch. Before you insert the bit, look into chuck for retaining pin. Pulling back on the spring loaded chuck releases pressure on the pin and allows insertion of bit. Parts are available at www.toolpartsdirect.com

This hammer may not need parts replaced. If it has not been serviced in a while you may only need to take apart lower half of hammer and wash out old grease and replace with either hitachi, bosch, dewalt, or skil grease. You can even use some skil worm saw lubricant sold at Lowes. Just clean and lube more often. This hammer works with air cushions action. The motor moves the piston and air trapped between the piston and striker moves the striker against the second hammer. This system does not work well if the grease if too thick or dirty or if the hammer is stored with bit facing up in the air. If parts look well lubed then may be issue with bit or second hammer may be stuck. Do not use bits with missing pieces or that have been ground where the second hammer strikes. Parts that need to be replaced will be obvious. But generally clean and lube will do the trick. Good luck

did you have the trigger in the locked position, some tools have a safety that you need to release the trigger after plugging back in to reset the switch. try that first.

You can find it here---> eReplacemntParts.

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