Demolition Hammer: Grinding or Squealing Sound

Worn bearings can cause a grinding and/or squealing sound. If you notice any of these sounds, it is a good idea to check and replace your bearings. The following repair procedure will vary on all models.

Begin by removing the handle from the unit. Remove the screw securing the motor housing and take it out of the unit. Spin the armature and bearing, checking for signs of roughness. If the bearings feel loose or rough when you spin them by hand, you will need to replace them.

Check for other signs of wear, such as grooves or damage. Remove the armature from the housing then from the bearing housing. You can do this by placing it in a vice then use a spanner wrench to spin the cap off on the back. You also can place a punch in the side of the notch on the cap, tapping it with a hammer to spin it loose. Remove the nut underneath the cap. By using a puller, place it over the bearing housing with the center on the shaft. Proceed to remove the housing away from the armature. At this point, the fan and brush ring will lift off.

With the armature bearing housing removed, use a socket and a hammer to tap the bearing out of the housing. Press the new bearing in by using a socket that is big enough to catch the outside of the bearing race to avoid damaging it during insulation. Place it in a press. If you do not have a press, use a socket big enough to go on the outside of the race on the bearing, tapping it in place gently with a hammer to avoid damaging it.

Install the fan and the brush holder back in the bearing housing, ensuring the tabs line up on the brush holder. Place the armature in the housing and reinstall the nut. Place in a vice to tighten. Spin the cap back on and tighten. Slide the armature back in the housing (the same way you removed it), then reattach the housing assembly back in the unit and secure the screws tight. Reattach the handle.

A broken fan can cause a grinding sound. The following repair procedure will vary on all models, depending on which side of the motor the fan is located on, but is similar.

To check the fan, remove the screws securing the housing for the motor and take it out if the unit. Pull the armature out of the housing and remove from the bearing housing by placing it in a vice. Using a spanner wrench, spin the cap off on the back or place a punch in the side of the notch on the cap, tapping it with a hammer to spin it loose. Remove the nut underneath the cap. Using a puller, remove the housing from the armature. At this point, the fan and brush will lift off.

Install the new fan and slide the brush ring back on, ensuring the tabs line up on the brush holder. Place the armature in the housing and reinstall the nut. Place in a vice to tighten. Spin the cap back on and tighten. Now, slide the armature back in the housing (the same way you removed it), then reattach the housing assembly back to the unit and secure the screws tight.

Worn, or stripped, gears will cause a grinding noise when the unit is turned on. The following repair procedure will vary on all models as they are set up differently with gears. You will have to study your model for the best method to remove and replace the gears.

To check and replace the gears, separate the handle and the motor housing from the demolition hammer. For this next step, depending on your model, you may or may not have to remove the barrel. Remove the barrel from the demolition hammer. While pulling the barrel away, remove the connecting rod from the eccentric gear, or crankshaft. Depending on your model, there may or may not be a retaining ring, or c-clip, holding some of these parts together. Other models, they simply lift off.

Remove the eccentric gear and check teeth for damage – replace if necessary. Reattach the connecting rod to the eccentric gear and reattach the barrel, motor housing and handle. For gears attached to the armature, place the armature in a vice and use a puller to remove the gear. To install a new gear on the armature shaft, freeze the armature in the freezer and heat the gear up and slide it over the armature shaft.

A lack of grease would cause the demolition hammer to squeal. To add new grease, remove the barrel from the demolition hammer and take out the connecting rod from the crankshaft. Set the barrel aside and remove the piston and striker. To remove any old, gummed up grease, clean all the parts in thinner and dry thoroughly. Lubricate the entire side of the barrel. Lubricate the piston lightly; you do not want a lot of grease on the inside of the piston. Lubricate the striker lightly as well with grease. Place the striker inside the piston and slide it back in the barrel. Lubricate the needle bearing. Slide the needle bearing on the crankshaft as you are reattaching the barrel to the demolition hammer.

A worn, or broken, piston rod will cause a grinding sound as the rod will bang around the inside of the cylinder when turned on. To replace the connecting rod, remove the barrel from the demolition hammer. While pulling the barrel away, remove the connecting rod from the eccentric gear, or crankshaft. Set the barrel aside and remove the piston and striker.

On some models, the connecting rod and piston are an all-in-one assembly. On other models, remove the piston retaining ring then slide the connecting rod pinout. Remove the old connecting rod and install the new one in the piston. Make sure it is right side up so the connecting rod does not make contact with the counterweight on the crankshaft. Slide the pin back in and reinstall the piston retaining ring. Slide the striker back inside the piston and install in the barrel. Reattach the barrel to the demolition hammer and add a dab of Loctite to the bolts holding the barrel on the demolition hammer.