In message , Dave W
writes
On Tue, 24 Dec 2019 09:39:00 +0000, Jeff Layman
wrote:

A bit of festive amusement, and perhaps something of interest for the
engineers here.

I have a garage with a roller door which is opened and closed by a
motor. A month ago it failed to open, and I had to use the manual winder
handle to open it. Strangely, it still closed automatically without
problem. Some checks showed it wasn't the remote or control box playing
up - it was the motor itself. This was a "roller" or "tubular" motor.
I'd never heard of these, but it was no trouble to order one on the
garage door supplier's website.

When it came it was a really strange beast. On reading the installation
instructions I chickened out and got some local pros to do it (it took
them about 2 hours), as it delivers 50Nm and I considered that could do
some damage if I got it wrong. Anyway, they left me the old one they
removed - which they confirmed was faulty - and I decided to dismantle
it and see what was inside. I had previously looked on the internet to
see if there was an "exploded" diagram of a tubular motor, but I
couldn't find one with sufficient detail.

The complete device itself is about 60 x 4.5 cm, with a motor at one end
which is fixed to the wall, and a drive shaft at the other which engages
with the roller door. What amazed me was the compound planetary gear.
I've never seen such a complex arrangement of cogs and pinions! I never
saw it in place in the roller door so don't know how it opened it. I
can't get my head round exactly how this works; internally the motor
gears (which have adjustable microswitches limiting the opening and
closing range) turn the orange tube. The extreme right-hand end of the
motor drive assembly has four screws which fix it to the orange tube. As
the motor itself is fixed by the large rectangular plate at the
left-hand end, when the motor turns the orange tube must turn. Note the
starter capacitor fits between the motor and the planetary gear end, so
there is no toothed drive shaft through from one end to the other. The
fixed planetary ring gear photo shows how the orange tube gear must
drive the planetary gear. The ring is fixed in place and not removable.
However, that ring only goes down 2 or 3 cm. There are then no teeth
until a cm or so above the plate where a toothed shaft comes through
(this shaft would mesh with the centre of the three epicyclic cogs on
the extreme left of the "disassembled compound planetary gear" photo,
but where the other end of that shaft goes to I have no idea!).
Unfortunately, no matter how I try I can't get that compound assembly
fully back in the tube, so can't see how the motor would turn it when
opening/closing the roller door. Anyway, somehow the tube rotates and
meshes with the extreme right-hand teeth of the compound planetary gear.
It's there my reasoning fails. Somehow the drive goes back through all
those planet and carrier gears to drive the final sun gear, which itself
leads to the flattened shaft at the extreme RH end of the compound
planetary gear. That shaft goes through the middle of the "roller door
drive mechanism" metal piece at the centre of that photo, which itself
somehow joins to the plastic bit on the left (all held on by a circlip),
and that somehow opens/shuts the roller door itself. Too many
"somehows"! See photos he

Tubular motor
https://ibb.co/HHy0R0S

Disassembled motor
https://ibb.co/3cH3xT1

Drive motor and limit switches
https://ibb.co/t8BWrfk

Compound planetary gear
https://ibb.co/mvdsd35

Disassembled compound planetary gear
https://ibb.co/qNK4NjB

Fixed planetary ring
https://ibb.co/d5b27N2

Roller door drive mechanism
https://ibb.co/xSDYXmJ

I assume that the inertia of the roller door allows the gearing to work
before it is able to move the door, but has anybody seen one of these
and can explain exactly how it works?

More detail please.

On 'Disassembled motor' there is a capacitor; is this what you call a
starter capacitor? There are still two wires going into the tube -
where to? I found a diagram of another tubular motor in which the
actual motor was in the middle of the tube, and only the limit swiches
were on the left.

On 'Fixed-planetary-ring', there is a six-toothed socket at the
bottom; is there a corresponding 6-toothed gear in the middle of the
planetary gears that fits? Is the socket fixed or does it rotate?
Perhaps it is on an internal motor shaft.

Is the flattened shaft on the right of the gears fixed to the housing
or connected to the planetary gears?

I have a duff one still fully assembled if anyone wants to play:-)

--
Tim Lamb