Electric Drill: Motor Spins but Chuck Doesn't

A broken, or stripped, gear will not be able to transfer power to the chuck. Some models house the gears in the front inside of the gear housing. To replace a worn, or broken, gear, remove the screws securing the gear housing cover to the front of the drill and remove the cover. Locate the broken or stripped gear.

Depending on the model, your gear may be an all-in-one unit on a small shaft or it can be removed from the shaft. To remove the gear on a shaft, install a hearing separator on the bearing and place the separator on top of the bench vice and tap on the shaft with a punch a hammer to free the bearing. Remove the retaining ring and wave washer, the broken gear and keyway.

Install the keyway and new gear on the shaft with the wave washer and retaining ring. Then, reinstall the bearing on the shaft using a socket on the race of the bearing and tap it in place using the hammer. Clean and re-grease the gears inside the housing. Reinstall the gear housing cover. On models that do not have front gear case, you will have to separate the two halves of the drill case to access the gears. Remove the shaft and gear assembly. Remove the bearing using a bearing separator. With the separator installed on the bearing, place it on top of the bench vice, open enough where it will not make contact with anything but the separator. Tap the shaft with a punch and a hammer until the bearing is free. Depending on your model, there may be a retaining ring that you can remove to separate the gears from the shaft.

Install the new gear, ensuring the keyway is installed on the shaft first, then reinstall the retaining ring and wave washer. On some models, you would replace the gear and shaft assembly as one. Reinstall the bearings on the shaft by placing the bearing on top of it, with a socket on the race of the bearing, to avoid damage. Tap it in place with a hammer. Reinstall the shaft on the drill and reassemble the drill case back together.   

A broken gear shaft will not be able to transfer power from the motor to the drill chuck. To replace a broken shaft, open the two halves of the drill or remove the front gear case cover. Locate the broken shaft and remove it from the drill. Note: on some models, the gear and shaft assembly may be an all-in-one unit. Use a bearing separator, or a bearing puller, to remove the bearing from the shaft. Remove the retaining ring, gear and keyway from the shaft and reinstall on a new shaft. Using a socket placed on top of the bearing race only, tap it in place with a hammer. Install the new shaft on the drill and reassemble the case, or gear housing over, back on the drill.

Over time, spindles can break, or crack, impacting their ability to transfer power. To replace a broken spindle, remove the chuck by inserting the proper screwdriver in the chuck to remove the chuck screw at the bottom. Snug the chuck on the screwdriver and remove the screw – this screw is reverse thread. Insert an allen wrench in the chuck and snug the chuck on the allen wrench, then hit the allen wrench with a hammer to loosen the chuck on the spindle. This may take a few hits with the hammer for any stubborn chucks. The chuck is reverse thread.

Once you have loosened the chuck, proceed to remove it. Remove the front gear case, or on models without a front gear case, separate the two halves of the drill case. Remove the spindle from the drill. Take out the bearing with a bearing separator, then remove the retaining ring, the gear and keyway. Install the keyway on the new spindle, then the gear with the retaining ring. Install the bearing using a socket placed only on the race of the bearing, to avoid damage. Tap in place with a hammer and reinstall back on the drill. Now, grease the gears. Reassemble the drill case, or gear case, back together. Install the chuck back on the spindle – this is in reverse thread. Insert an allen wrench in the chuck and snug the chuck on the wrench and hand tighten. Install the chuck screw hand tight, in reverse thread.