I'm trying to help a disabled fellow repair the electric powerlift on
his garden tractor. The motor gear is 32 pitch, 16 tooth, 0.58 face,
5/16 bore. I'm stuck on a couple of things. The bore is D shaped; the
motor shaft has a flat. There is no hub and no set screw. Gear is
sandwiched between the motor and an outboard pilot bearing in the
housing. I'm no machinist, so I'm looking for some direction here.
Maybe saw off a sliver of shaft and solder it in the bore?

Number two is how to determine the pressure angle of the teeth. 14.5°
or 20°. The gear is 27 years old if that is clue. Oh, did I mention
parts are no longer available.

There is a third problem. I have only the gear; not the motor. Trial
fit is not possible.

I've found lots of gear sources but would welcome more.

Can you machine down the original gear until you just have the boss,
make a new gear without a centre, and weld the original boss inside?

Just a thought...

Chris

Just had a look at a gear catalogue. Looks like that gear is little
more than 1/2" diameter. Damn. That's a little small for welding in a
replacement boss. Could you make a new gear with a circular bore and a
grubscrew instead of a D-shaped bore?

Chris

On 12 Feb 2006 17:44:27 -0800, "Christopher Tidy"
wrote:

Just had a look at a gear catalogue. Looks like that gear is little
more than 1/2" diameter. Damn. That's a little small for welding in a
replacement boss. Could you make a new gear with a circular bore and a
grubscrew instead of a D-shaped bore?

Chris

Another problem. The gear face is just over 0.5" and meshes with a
1/4" face gear that lines up right in the center of the smaller gear.
Of course, the worn out section is in the center. I've thought about
cutting the gear in two and rearranging the parts so unworn teeth are
now in the center. That is my last choice though.

I'm no machinist. Gear stock is available but the D hole is a stumper.

Also, I haven't figured out if it is 14.5° or 20° pressure angle. Any
ideas on that?

Andy Asberry wrote:
On 12 Feb 2006 17:44:27 -0800, "Christopher Tidy"
wrote:

Also, I haven't figured out if it is 14.5° or 20° pressure angle. Any
ideas on that?
I would -guess- at 14.5 degrees.

Pete

"Andy Asberry" wrote in message
news
On 12 Feb 2006 17:44:27 -0800, "Christopher Tidy"
wrote:

Just had a look at a gear catalogue. Looks like that gear is little
more than 1/2" diameter. Damn. That's a little small for welding in a
replacement boss. Could you make a new gear with a circular bore and a
grubscrew instead of a D-shaped bore?

Chris

Another problem. The gear face is just over 0.5" and meshes with a
1/4" face gear that lines up right in the center of the smaller gear.
Of course, the worn out section is in the center. I've thought about
cutting the gear in two and rearranging the parts so unworn teeth are
now in the center. That is my last choice though.

I'm no machinist. Gear stock is available but the D hole is a stumper.

Also, I haven't figured out if it is 14.5° or 20° pressure angle. Any
ideas on that?
I think I would make a shaft to fit the old gear, then silver solder a piece
in the new bore as you suggested. I would make the piece a little oversize
and carefully file to fit the shaft just like the old gear fits.

I do not think there is an easy way to measure the pressure angle,
especially on such a small gear. I think it would be possible by measuring
the diameters over two wires or pins of suitably different diameters to
measure the taper of the tooth space but the math seems pretty complicated.
Hope someone else can help on that.

Don Young

On 12 Feb 2006 21:44:36 -0800, wrote:

Andy Asberry wrote:
On 12 Feb 2006 17:44:27 -0800, "Christopher Tidy"
wrote:

Also, I haven't figured out if it is 14.5=B0 or 20=B0 pressure angle. Any
ideas on that?
I would -guess- at 14.5 degrees.

Pete

I had a similar problem replacing a gear on my Excello mill. Just
take the gear to a local shop that specializes in bearings & power
transmission (gears, sprockets, chain, belts, etc.) Most of these
places have gauges that identify the pitch and pressure angle of a
gear tooth, and can check yours for you.

John Normile