Hitachi drill jaws do not move, can not hold bit

It's possible that the jaws of your drill's chuck have worn down and become rounded, which is causing the bit to not be held securely. One solution to this problem would be to replace the chuck with a new one. However, before you do so, you may want to try tightening the chuck as much as possible to see if that helps. If it still won't hold the bit properly, then it's likely that the chuck needs to be replaced.

Hmmm some times the counterclockwise screw that attaches the chuck to the drill come forward and that is how then it stucks the 3 parts that fix a drill to a chuck. Check if this screw come forward. If yes then destroy it and replace it... We destroy it by using a drill smaller than it (usually it is 5mm so we use 4mm bit and of course a CARBIDE one because even cobalt ones can not drill a hardened bolt)

Put the dril in forward, hold the collar, and just bump the switch long enough to get the internal portion to turn. The bit will likely fall out at that point.

Keyless chucks are make in a way that each of the jaws have an exposed heel that can grab onto larger bits that were inserted too far into the chuck.

I'm assuming this is a drill/driver but you did not indicate a model. If it's a keyless chuck, and most are, put the drill in reverse, hold the chuck housing near the body of the drill firmly and pull the trigger. the chuck jaws will open wide enough to remove the old bit and insert new one. To tighten, switch the drill into forward gear, hold the chuck and pull the trigger until the bit is firmly held in the jaws.

Refer to the picture shown in the link below--- http://mydeco.com/p/powerbase-xtreme-cordless-hammer-drill-kit-18v/GB000024EPS6TLCLTKLEGSM4VU6S7ICXK7PGDYPU/
The very left-hand end of the drill is the drill chuck. There are three "jaws" protruding from the left-most end. To open the jaws grasp the large black collar with one hand and the the smaller silver collar just behind it with the other hand. Twist these two collars in opposite directions. You have to twist pretty hard. If they won't move, then try the other direction. Once they start to move they will move easily and you will see that the the three jaws begin to separate. Keep going until the jaws have separated enough to insert the wood drill bit, insert the bit, then tighten - good and tight! Good luck.

You may try to put a thick soft metal pipe (aluminium or copper) over the drill bit (longer than the bit itself by ~10 mm) so it will touch the chuck's jaws, then GENTLY hit the other end of the pipe with a hammer several times, holding the pipe a bit askew, thus trying to disengage the jaws from the lock in their thread, and try to loosen the chuck after each series of hits. Just be careful with your fingers, and better hold the drill by the chuck while hammering it - so the hits won't go to the transmission unit (sorry for description - hope it's understandable, if not - ask for clafication from me)

Well I couldn't find a pix of your drill so I will guess that it is a typical drill. You seem to be asking a very basic question so I will start will all the basic info I can think of.

First you have to know where the power trigger is to make it go.

2nd you have to know where the forward and reverse switch is.

Now with the switch in the forward position squeeze the trigger to make it go. Then gently grab the chuck with your hand while it is going and the center Jaws should close up and come out of the chuck.

Now with the switch in the reverse position squeeze the trigger to make it go. Then gently grab the chuck with your hand while it is going and the cetner Jaws should open up and go into the chuck to a maximum point

Open the jaws enough to put the drill in the jaws then put the switch in the forward position. Put the drill in the chuck, sqeeze the trigger to make it go, and hold the chuck so the jaws close on the drill. All while keeping the drill from falling out of the chuck.

When it closes on the drill and the drill is in straight then hold the chuck as tight as you can while squeezing the trigger to make the jaws close very tightly on the drill. If you have very tender hands you might want to use gloves.

To get the drill out put the switch in reverse, hold the chuck very tightly, and squeeze the trigger to open the jaws off of the drill.

Your chuck is jammed. You can use a punch that is the same size as the jaws and a small hammer. You can tap the jaws back with the punch ever so slightly. Tap on each jaw the same amount of times. Start on one jaw with one tap, then to the next, and then to the third. After tapping each try to turn the chuck to open. This will dislodge the jaws slighlty and you should be able to move it. Keep doing this until you can open the chuck or remove the bit. After removing the bit spray some lubricant into the chuck and work it back and forth the whole length of the jaws. If this does not work you can put the bit in a vise and use a rubber or soft end hammer to hit the chuck off the bit. In this case you will have to replace the chuck. There is probably a bad spot in the jaws that is stripped.

You can use a punch and hammer to tap the jaws back in slightly and turn the chuck as you do this to each jaw. This will at least let you get your bit out. You need to hit it hard enough to move it but not too hard as to damage it. Finesse it. After removing the bit try working the chuck jaws in and out all the way. If you feel resistance you may want to get a new chuck.

Other than two quick squirts of WD40 and nice new chuck key?