On 26/12/19 20:29, Dave W wrote:
On Tue, 24 Dec 2019 20:36:30 +0000, Jeff Layman
wrote:
On 24/12/19 18:32, Dave W wrote:
On Tue, 24 Dec 2019 09:39:00 +0000, Jeff Layman
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.
Actually, there are three wires - see below.
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.
Yes, It is the six-toothed central sun gear spindle on the left-hand
side of the "Disassembled compound planetary gear" photo. It had slipped
through a bit to the right, but in practice extends past the plastic
planet gears into that 6-toothed socket, as well as meshing with the
metal planet gears in the middle gear assembly. That socket must be the
power drive from the motor.
Is the flattened shaft on the right of the gears fixed to the housing
or connected to the planetary gears?
It is part of the planet gears. It's not easy to see in the
"Disassembled compound planetary gear" photo, but the fixed bit is the
dull grey round piece with the lugs and screw hole which hold it in
place on the orange tube. The shaft passes through that and is one
single piece with the shiny round part holding the four planet gears. So
if the shaft is turned, the four planet gears rotate. In practice, of
course, it's the other way round - the central sun spindle of the middle
gear assembly rotates, thus causing the four planet gears to rotate, and
so causing the flattened spindle to rotate.
I'll get back to you after Christmas on these points. You could be right
that the motor is in the middle - the wires disappearing inside puzzled
me. I had assumed they might be going to some thermal or mechanical
overload switch. Unfortunately the middle bit (under the fixed planetary
ring) seems to be potted or is otherwise fixed in. I couldn't see how,
but I'll have another look. I might also try to connect it all up to the
power and see what turns where.
In you first paragraph you mention a diagram of another tubular motor
with the motor in the middle. Do you have a URL for that?
I looked at loads of tubular motors, which are apparently only used in
roller shutters, but today I found again:
https://www.britshutter.com/tubular-motor/
It has the motor in the middle, but I don't think all tubular motors
are the same.
Thanks for that URL - it explains things neatly. My tubular motor is of
the same construction; it's a 45M404-50
(https://www.nrgautomation.co.uk/radio-controls-3)
You are right that the motor is in the middle. What has - and up to a
point still does - confuse me is how the reversible AC motor works. I
had assumed it was at one end as that's where the lead from the control
unit entered. I still haven't completely dismantled that end of the
tubular motor (by the rectangular fixing plate which I had assumed
concealed the motor) to see what is inside. It may only be the limit
switch controls.
The power lead from the main control unit has four leads - earth, blue
(common), brown (down), and black (up). The brown lead and black leads
are interrupted by their own (adjustable) microswitch limit switches.
They then, with the blue lead, go to the central motor. But the
capacitor (which is 8uF 5% 450V AC) connects across the brown and black
leads only. Harry mentioned a separate start winding being required for
a single-phase reversible motor, so I'll have to look up reversible AC
motors later to find out why it is connected that way.
However it works, I have to agree with the statement on that URL you
supplied:
"This type of tubular motor is designed by international advanced
technology..."
I'd love to know how they design how those gears will work!
--
Jeff