ew oil pump drive

[kev]

   I have made a gear up for my oil pump...but it doesn't seem to mesh real well with the drive worm

I know there are 2 types of pump drive...but I don't know what I have...my worm is a pretty good match at a 10 pitch...  and the oil pump gear (half the teeth are missing)   is a 20 tooth model....  sooooooooo  what do I have??

if I have to I will cut another worm gear..make it into a cutter and chew out a matching gear...but wouldn't you know it..the only length of K245 I have is .020 undersize

I have ordered a #5BA tap from tracey,s...to make the little drive pin...I would assume that should be glass hard??

I don't have any one way valve in this pump...do they just work by inertia???
 

[eddie]

From the photo, your gear looks to have straight cut teeth - to mesh correctly with a worm, the teeth will need to be helical! To obtain this, the cutter will need to be tipped to the appropriate angle and the dividing head geared to the table feed to produce the correct helix. Having made the first cut, the cutter will need to be moved clear of the job before moving back to start the next tooth, otherwise it will take a second cut on the return due to the backlash in the feed to the dividing head.

  Regards,
               Eddie.

[kev]

eddie

thanks for the reply

  would make perfect sense to have helical gears...likely wouldn't have worn out like they did...as the pressure angle is on a pinpoint

but all of the pictures I have seen of oil pump gears...teeth are straight cut...not helical...a bit different tooth shape...  but I am working with what I have..i have found a mob that will custom grind an involute......maybe a better match

what I may do if I cant find any other solution is cut a worm....machine and harden into a cutter and cut a matching gear...??? 

your system sounds pretty good but a fair bit beyond my limited abilities...

first I just need to find out number of teeth on a fine tooth pinion and the number of teeth on a coarse pinion...see if either one matches better to my existing worm...
I just don't know if I have the fine or coarse??? or what the tooth count is...my worm is a good match to a 10 pitch...and my pinion is a 20 tooth...and about 10 of those teeth are cactus

[Doug]

I gave away the example of the 24 tooth gear/cam that I had. But as I recall it was a spur gear and not a helical gear. To work with a worm, it should be a helical gear with a helix angle matching the pitch of the worm. But Douglas thought they could simplify it and used a spur gear with straight teeth. To get that to work, they made the width of the gear narrow and thinned the gear tooth to make it clear the worm. The tips of the tooth nearly came to a point. Combining that with the minimal depth of engagement is why the earlier EW worm and gear were prone to stripping.

-Doug

[kev]

  doug

thanks heaps for the reply...
  the 20 tooth I have is a spur gear....not a helix...  and no doubt is the reason that after 80 years..is just plain worn out...  and not having the  "hunting" teeth on my cam drive gear train is likely why I see wear in particular areas there as well

seriously though...what did douglas in mind for a service life...  after all...motorised transportation didn't even have 20 years of history at the time they pushed  my current bit of frustration out of their shed.......like I tell my friends...the dougy engineers when they ran into a problem...there wasn't a junkyard out the back where they go see how somebody else solved that problem...
    just using google and you tube...most any engineering problem is solved... did the dougy factory even have electric lights to work under???

  what I,m gonna try...
make a new worm with a 10 tpi..same as mine...outta some 4140...harden it and notch out as a cutter and use it to see if I can hob out a helix type gear for my pump...??  see if it goes all the way around and back into the starting tooth...or even close enough??  not sure how to mathematically work out the diameter...numbers have never been my friend..
my original gear has rust pits..and being hardened..eats my 1020 spur at a very quick rate...(using a battery drill to operate..) if even a 20 tooth spur and a 10 pitch worm are a match?? setting up on my outer plate.....seems to be maybe 040+ short of diameters....or more..??

my hob is a standard volute...produces a rounded tooth as opposed to douglas straight tooth...worst case...one I have a match...meshing gears...easy enough to grind my BRAND NEW volute to straight teeth...... not a big deal as comes off china ebay..under $30.00 and has done 5 practice gears and only sharpened once so far

if it all works...I,ll have a some matching oil pump drives...or..as Edison said...as said about his light bulb...I have just eliminated another non solution..

one thing I have to give douglas credit for...this old murdercycle has greatly lifted my game in the engineering department...before this project...I was quite happy with my lathe...mill...now definitely trade in time on these cast iron lumps

the crank...I keep reading about a valve in the end...flapper or ball and spring...  I have nothing...  any pictures...details..  greatly appreciated 
1926 ew

this mighty douglas will once again oil the roads of queensland

[kev]

\  made some gears...what do you reckon??

  made up a cutter out of a chunk of 4140..hardened it...made up a jig for my lathe..  used an alloy blank and my cutter hobbed out a nice little pump gear
interesting...as  I understand.....douglas pump gear is 20 or 24 tooth????    my 10 pitch worm...cut a neat 26 tooth helix pinion...??  no wonder my 20 tooth ran as rough as a rock   ...now just need to cut a steely gear for my pump...and I,ll have this side of the motor done

if any advice...let it fly...this is not my line of work...I,m basically just  doing an Oscar...shooting thru the door...   just the only way I could work out
any advice and help appreciated

[kev]

heres some more...now I have also worked out the picture posting thing

[kev]

last of the pictures...
as you can tell.... I,m pretty pumped...

   this mighty douglas will once again... oil the roads of queensland