[Dewalt DCD939 Hammer Drill]

i'm am not an expert so take this with a grain of salt. all my drills that i have taken apart out curiosity or to fix, all of them seem to work on the same principle regarding the torque ring. the way i can only explain it is that the ring is like a screw that pushes a spring. ...

part #28 from this link...

http://www.ereplacementparts.com/dewalt-dcd939-type-144v-hmrdrdrilldrivedriver-parts-c-1009_9661_25052.html

at 1st setting, the ring is pushing on the spring very little...at the highest setting the spring is fully compressed.

now what causes the slip of the chuck is either some bearings or just washer bushings...think putting ur hands together and rubbing them...the harder you press ur hand together, the harder it is to rub them together (friction)...

having said that...that is where i would put my money...maybe u dropped a bearing or just put it back wrong where the outer ring sleeve (the one with the numbers) is not compressing the spring.

this drill is taken out of commission so i have it for parts...in this drill it usses a series of spring that push on bearings..(bearings ride on a metal ring that has groves)

at pic 1 it is set at one and at pic 2 it is set at highest...where is locks the chuck to the transmission.

Thank You Joe for your reply yes the basic principle of the torque ring is as you subscribe it,but this ring in my tool push correct the spring the issue may in the spindle that came out from the transmission gear. Look close the photo here

http://www.google.gr/imgres?um=1&hl=el&client=firefox-a&hs=xvo&sa=N&tbo=d&rls=org.mozilla:el:official&biw=1280&bih=624&tbm=isch&tbnid=_YECDyh5OETusM:&imgrefurl=http://www.ebay.ie/itm/Dewalt-Transmission-397892-05SV-gear-box-dc988-dw988-dw987-dc983-dc989-dw989-/180932982088&docid=L_A_2ochrc07xM&itg=1&imgurl=http://i.ebayimg.com/00/s/OTAwWDE2MDA%253D/%2524%28KGrHqR,!jgE%252BSePTeP%28BQCIc3WJ1w~~60_3.JPG&w=800&h=450&ei=YaEHUay1IaKk4gSXu4CoDw&zoom=1&ved=1t:3588,r:44,s:0,i:220&iact=rc&dur=441&sig=107120819382660460149&page=2&tbnh=168&tbnw=300&start=24&ndsp=29&tx=119&ty=85

[Dewalt DCD939 Hammer Drill]

Hi to all member.I'll ask for your help about my drill.Recently I open and dismantle my DCD939 for inner cleaning purpose but after that and after closing the tool again and screwing all the screws the torch scale in the front from 1-21 torque scale is not work well,and I mean when I put the ring to the 1(first) scale the clutch is not work the chuck don't stop so the clutch make his work but keep running and this happen to all stage from 1 to 21 of torque scale.I reopen and close the tool several time i think I put everything in place because the the scale of normal drilling is working well as the hammer too,but now I can't use it as screwdriver and i don't know what is wrong.Unfortunately here in my town don't exist any Dewalt service station and so I don't know what to do?

All suggest is welcome.

[HOW TO REMOVE THE ROHM SUPRA SK CHUCK!]

Quick question:

I have read the Rohm chuck should never be opened or closed by using the drill itself, rather only hand-tighten the chuck with the spindle locked.  Is this true?  I never had a problem with my DC927 chuck until I lent my drill to a friend and he used the drill motor to tighten the chuck onto a bit.  Afterwards the chuck would lose it's grip if I tried to free a stuck bit in reverse.  Never had that issue prior.  Now I have bought a 700 Jacobs chuck to replace the old Rohm, and I won't lend out my $300 drill again.

Thanks,

Jeff

I have never heard of using the motor to open or close the chuck being a problem.  I will not go so far as to say what is the proper way to use it, but I always (as in EVERY time) use the motor to tighten or loosen my chuck.

Yes it does exist in some manufactures key less chuck ,Metabo chuck does this to prevent the chuck from destroy it and you must then open the key less chuck removing the safety clutch behind the chuck and loose the chuck.

[Make your cordless tool hybrid with a power supply]

Thank You Very Much believe me you are the only man so far that present a complete project solution for that issue.With so many bare body of a bare drill it is an one of a kind solution,but i want to ask you can safely someone use it with other tool as saw's or grinder that hold a lot of current when they start and during a job that you want to complete?